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1
Wareham, Christopher D., Ian L. Millar, and Alan P. M. Vaughan. "The generation of sodic granite magmas, western Palmer Land, Antarctic Peninsula." Contributions to Mineralogy and Petrology 128, no. 1 (June 25, 1997): 81–96. http://dx.doi.org/10.1007/s004100050295.
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Scarrow, Jane H., R. J. Pankhurst, P. T. Leat, and A. P. M. Vaughan. "Antarctic Peninsula granitoid petrogenesis: a case study from Mount Charity, north-eastern Palmer Land." Antarctic Science 8, no. 2 (June 1996): 193–206. http://dx.doi.org/10.1017/s0954102096000260.
Повний текст джерелаАнотація:
At Mount Charity, north-eastern Palmer Land, Rb–Sr whole-rock dating has identified three successive phases of granitoid emplacement in Triassic (232 ± 4 Ma), Jurassic (168 ± 1 Ma), and Cretaceous (120 ± 4 Ma) times. The Triassic suite comprises tonalites, granodiorites (including one two-mica granodiorite), monzogranite and a granite having either I-type or S-like mineralogies. The Jurassic suite includes only S-like granites, and the Cretaceous biotite tonalites and biotite granodiorite are all I-type. The three suites have negative ∈Nd and positive ∈Sr, and have subtly different Nd and Sr isotope characteristics: Suite A, ∈Srt =+30 to +53 and ∈Ndt =−0.9 to −3.1, Suite B, ∈Srt =+43 to +64 and ∈Ndt =−2 to −5.3, Suite C, ∈Srt =+22 to +23 and ∈Ndt =−2.5 to −2.6. Mineralogical and compositional differences between the three suites suggest that different sources were tapped. All the granitoids are isotopically intermediate in composition between Palmer Land crust and depleted asthenosphere. We suggest that the I-type granitoids were produced by melting of meta-igneous crust; by contrast, the S-like granitoids represent partial melts of garnet-bearing sedimentary crust. Syn-magmatic structures in Suite A are compared with known structural events in western Palmer Land and suggest that extension controlled Triassic pluton emplacement. The Jurassic magmas were also emplaced during an episode of arc extension, and intrusion of the Cretaceous magmas was probably controlled by regional extension and dextral transtension. Successive phases of magmatism focussed at Mount Charity are consistent with reactivated faults acting as magma conduits.
3
Davis, B. K. "Synchronous syntectonic granite emplacement in the south palmer river region, Hodgkinson Province, Australia." Australian Journal of Earth Sciences 41, no. 2 (April 1994): 91–103. http://dx.doi.org/10.1080/08120099408728118.
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Leat, Philip T., and Jane H. Scarrow. "Central volcanoes as sources for the Antarctic Peninsula Volcanic Group." Antarctic Science 6, no. 3 (September 1994): 365–74. http://dx.doi.org/10.1017/s0954102094000568.
Повний текст джерелаАнотація:
From at least the Early Jurassic to the Miocene, eastward subduction of oceanic crust took place beneath the Antarctic Peninsula. Magmatism associated with the subduction generated a N-S linear belt of volcanic rocks known as the Antarctic Peninsula Volcanic Group (APVG), and which erosion has now exposed at about the plutonic/volcanic interface. Large central volcanoes from the APVG are described here for the first time. The structures are situated in north-west Palmer Land within the main Mesozoic magmatic arc. One centre, Zonda Towers, is recognized by the presence of a 160 m thick silicic ignimbrite, containing accidental lava blocks up to 25 m in diameter. This megabreccia is interpreted as a caldera-fill deposit which formed by land sliding of steep caldera walls during ignimbrite eruption and deposition. A larger centre, Mount Edgell-Wright Spires, is dominated by coarse-grained debris flow deposits and silicic ignimbrites which, with minor lavas and fine-grained tuffs, form a volcanic succession some 1.5 km thick. Basic intermediate and silicic sills c. 50 m thick intrude the succession. A central gabbro-granite intrusion is interpreted to be a high-level magma chamber of the Mount Edgell volcano.
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XU, XI-SHENG, KAZUHIRO SUZUKI, LEI LIU, and DE-ZI WANG. "Petrogenesis and tectonic implications of Late Mesozoic granites in the NE Yangtze Block, China: further insights from the Jiuhuashan–Qingyang complex." Geological Magazine 147, no. 2 (October 27, 2009): 219–32. http://dx.doi.org/10.1017/s0016756809990367.
Повний текст джерелаАнотація:
AbstractThe Jiuhuashan–Qingyang complex is one of the Mesozoic granite complexes in the NE Yangzte Block, China. New petrographical and petrochemical data show that the complex comprises a dominant granodiorite–monzogranite, the Qingyang body, which was intruded by the Jiuhuashan granite body. The two are characterized by distinct mineral components and trace element patterns. Compared to the Qingyang granodiorite and monzogranite, the Jiuhuashan granite is enriched in Rb, Th, U, Nb, Ta, Hf, Yb and Lu, and depleted in Ba, Sr, Nd, Sm, Eu, Gd and Ti, which are ascribable to the separation of plagioclase and biotite, and crystallization of thorite and fergusonite during the magmatism. New LA-ICPMS zircon U–Pb dating suggests that the crystallization age of the Qingyang body is 139–133 Ma, and the Jiuhuashan granite followed at 127 Ma. Moreover, the new zircon U–Pb dates reveal that Archaean materials were involved in the formation of these magmas, and that a sodium-rich metasomatic event occurred at about 100 Ma. The CHIME monazite and zircon ages studied for the Jiuhuashan body agree well with the LA-ICPMS zircon ages. Integrating this information with previous studies for granites in the NE Yangtze Block and in the coastal area of SE China, we believe that all of these Late Mesozoic granites were produced under the tectonic regime of palaeo-Pacific plate subduction towards the SE China continent in a NW direction, but the granites in the NE Yangtze Block are basically derived by crustal melting with limited mixing of juvenile material during the magma generation.
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CHEN, LING, CHANG-QIAN MA, ZHEN-BING SHE, ROGER MASON, JIN-YANG ZHANG, and CHAO ZHANG. "Petrogenesis and tectonic implications of A-type granites in the Dabie orogenic belt, China: geochronological and geochemical constraints." Geological Magazine 146, no. 5 (January 19, 2009): 638–51. http://dx.doi.org/10.1017/s0016756808005918.
Повний текст джерелаАнотація:
AbstractThe Dabie orogenic belt is characterized by the presence of large volumes of intrusive and volcanic rocks that formed in Late Mesozoic times. Most of the intrusive bodies are I-type granites but it is still unclear whether there are contemporary A-type granites. Here, we report the first unambiguous discovery of A-type granite from Baiyashan in the North Dabie tectonic belt. The crystallization age of the body has been fixed as 120.4 ± 1.2 Ma using U–Pb analysis of zircons by LA-ICPMS. The Baiyashan granite is enriched in Si, K, Na, Rb and REE, has elevated FeOtot/(FeOtot + MgO) and Ga/Al ratios, and is depleted in Mg, Ca, Mn, Ba, Sr, P and Ti. The REE composition shows highly fractionated patterns with (La/Yb)N = 6.95–16.68 and Eu*/Eu = 0.33–0.59. Its crystallization age, field relationships, petrographic and geochemical data show beyond doubt that the Baiyashan granite is an Early Cretaceous A-type granite. Sr–Nd isotope systematics are characterized by a high ISr of 0.708–0.714 and a low ɛNd of −7.5 to −19.4, with TDM2 = 1.5–2.5 Ga, and these data indicate that the magmas were dominantly sourced from partial melting of middle to lower crustal intermediate-felsic igneous rocks and mingling with mafic to intermediate magmas, during rift-related magmatism associated with subduction of the Palaeo-Pacific Plate beneath Eastern China in Early Cretaceous times.
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ZENG, QING-DONG, JIN-HUI YANG, JIAN-MING LIU, SHAO-XIONG CHU, XIAO-XIA DUAN, ZUO-LUN ZHANG, WEI-QING ZHANG, and SONG ZHANG. "Genesis of the Chehugou Mo-bearing granitic complex on the northern margin of the North China Craton: geochemistry, zircon U–Pb age and Sr–Nd–Pb isotopes." Geological Magazine 149, no. 5 (November 24, 2011): 753–67. http://dx.doi.org/10.1017/s0016756811000987.
Повний текст джерелаАнотація:
AbstractThe Chehugou granite-hosted molybdenum deposit is typical of the Xilamulun metallogenic belt, which is an important Mo–Ag–Pb–Zn producer in China. A combination of major and trace element, Sr and Nd isotope, and zircon U–Pb isotopic data are reported for the Chehugou batholith to constrain its petrogenesis and Mo mineralization. The zircon SIMS U–Pb dating yields mean ages of 384.7 ± 4.0 Ma and 373.1 ± 5.9 Ma for monzogranite and syenogranite and 265.6 ± 3.5 Ma and 245.1 ± 4.4 Ma for syenogranite porphyry and granite porphyry, respectively. The Devonian granites are calc-alkaline with K2O/Na2O ratios of 0.44–0.52, the Permian granites are alkali-calcic with K2O/Na2O ratios of 1.13–1.25, and the Triassic granites are calc-alkaline and alkali-calcic rocks with K2O/Na2O ratios of 0.78–1.63. They are all enriched in large-ion lithophile elements (LILEs) and depleted in high-field-strength elements (HFSEs) with negative Nb and Ta anomalies in primitive mantle-normalized trace element diagrams. They have relatively high Sr (189–1256 ppm) and low Y (3.87–5.43 ppm) concentrations. The Devonian granites have relatively high initial Sr isotope ratios of 0.7100–0.7126, negative ɛNd(t) values of −12.3 to −12.4 and 206Pb/204Pb ratios of 16.46–17.50. In contrast, the Permian and Triassic granitoids have relatively low initial 87Sr/86Sr ratios (0.7048–0.7074), negative ɛNd(t) values of −10.1 to −13.1 and 206Pb/204Pb ratios of 17.23–17.51. These geochemical features suggest that the Devonian, Permian and Triassic Chehugou granitoids were derived from ancient, garnet-bearing crustal rocks related to subduction of the Palaeo-Asian Ocean and subsequent continent–continent collision between the North China and Siberian plates.
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DENG, XIN, KUNGUANG YANG, ALI POLAT, TIMOTHY M. KUSKY, and KAIBIN WU. "Zircon U–Pb ages, major and trace elements, and Hf isotope characteristics of the Tiantangzhai granites in the North Dabie orogen, Central China: tectonic implications." Geological Magazine 151, no. 5 (December 18, 2013): 916–37. http://dx.doi.org/10.1017/s0016756813000976.
Повний текст джерелаАнотація:
AbstractCretaceous granites are widespread in the North Dabie orogen, Central China, but their emplacement sequence and mechanism are poorly known. The Tiantangzhai Complex in the North Dabie Complex is the largest Cretaceous granitic suite consisting of six individual intrusions. In this study, zircon U–Pb ages are used to constrain the crystallization and protolith ages of these intrusions. The Shigujian granite is a syn-tectonic intrusion with an age of 141 Ma. This granite was emplaced under a compressional regime. Oscillatory rims of zircons have yielded two peaks at 137±1 Ma and 125±1 Ma. The 137±1 Ma peak represents the beginning of orogenic extension and tectonic collapse, whereas the 125±1 Ma peak represents widespread granitic magmatism. Zircon cores have yielded concordant ages between 812 and 804 Ma, which indicate a crystallization age for the protolith. The Tiantangzhai granites show relatively high Sr contents and high La/Yb and Sr/Y ratios. The Shigujian granite has positive Eu anomalies resulting from partial melting of a plagioclase-rich source in an over-thickened crust. Correspondingly, in situ Lu–Hf analyses from zircons yield high negative εHf(t) values from −24.8 to −26.6, with two-stage Hf model ages from 2748±34 to 2864±40 Ma, suggesting that the magmas were dominantly derived from partial melting of middle to lower crustal rocks. The Dabie orogen underwent pervasive NW–SE extension at the beginning of the early Cretaceous associated with subduction of the Palaeo-Pacific plate beneath eastern China.
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Clift, Peter D., Amy E. Draut, Robyn Hannigan, Graham Layne, and Jerzy Blusztajn. "Trace element and Pb isotopic constraints on the provenance of the Rosroe and Derryveeny formations, South Mayo, Ireland." Transactions of the Royal Society of Edinburgh: Earth Sciences 93, no. 2 (June 2002): 101–10. http://dx.doi.org/10.1017/s0263593300000353.
Повний текст джерелаАнотація:
The Rosroe Formation comprises a series of Lower Ordovician (Llanvirn) conglomerates and sandstones, that lies on the southern limb of the South Mayo Trough, within the Iapetus Suture Zone of western Ireland. Trace element chemistry of granite boulders within the formation indicates a continental, rather than a volcanic arc character that can be correlated to latest Precambrian granites within the Dalradian Metamorphic Block, part of the deformed Laurentian margin. A minority of the clasts may correlate with syn-collisional granites, similar to, but older than, the Oughterard Granite of Connemara. Pb isotope compositions of K-feldspar grains within the sandstones, measured by both ion microprobe and conventional mass spectrometry, show a clear Laurentian affinity, albeit with greater source variability in the sand grains compared to a limited range in the proximal boulders. Palaeo-current indicators demonstrate dominant derivation from the NE, with a significant axial E–W flow. We propose that the Rosroe Formation records unroofing of a rapidly exhuming Dalradian metamorphic belt in North Mayo, following extensional collapse of the Grampian Orogen starting at ˜468 Ma, with minor input from a southerly arc source. The lack of metamorphic input from the S until deposition of the Derryeeny Conglomerate argues that the Connemara terrane was not positioned S of South Mayo Trough through strike-slip faulting until after the end of Rosroe sedimentation (460–443 Ma).
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LIU, CHANGFENG, ZHIGUANG ZHOU, YONGJU TANG, CHEN WU, HONGYING LI, YAN ZHU, TIAN JIANG, WENCAN LIU, and BAOYING YE. "Geochronology and tectonic settings of Late Jurassic – Early Cretaceous intrusive rocks in the Ulanhot region, central and southern Da Xingan Range." Geological Magazine 154, no. 5 (June 24, 2016): 923–45. http://dx.doi.org/10.1017/s0016756816000418.
Повний текст джерелаАнотація:
AbstractZircon U–Pb dating and whole-rock geochemical analysis have been performed on Late Jurassic – Early Cretaceous intrusive rocks of the Ulanhot area, NE China, with the aim of constraining the tectonic evolution of the central and southern Da Xingan Range. Zircon U–Pb dating indicates that Late Jurassic – Early Cretaceous magmatic events experienced four stages at:c.155 Ma;c.144 Ma; 135–130 Ma; andc.126 Ma. Thec.155 Ma magmatic event consists of quartz diorite and granite-porphyryp with the geochemical characteristic of high Sr and Sr/Y or high A/CNK (1.38), implying the primary magma was derived from partial melting of a thickened lower crust which induced the closure of the Mongol–Okhotsk Ocean. Thec.144 Ma magmatic event consists of quartz monzodiorite with the geochemical characteristics of alkaline series, and indicates the delamination of a thickened crust. The 135–130 Ma magmatic event consists of syenogranite and granite-porphyry with characteristics of both I-type and A-type granites, which induced both the subduction of the Palaeo-Pacific oceanic plate and the post-orogenic extension of the Mongol–Okhotsk Orogenic Belt. Thec.126 Ma magmatic event consisted of highly fractionated I-type biotite granite and alkaline series gabbro, marking the end of the Mongol–Okhotsk Orogen, and implying that the study area was controlled by the circum-Pacific tectonic system during this stage.
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JIANG, YAO-HUI, SHAO-YONG JIANG, KUI-DONG ZHAO, and HONG-FEI LING. "Petrogenesis of Late Jurassic Qianlishan granites and mafic dykes, Southeast China: implications for a back-arc extension setting." Geological Magazine 143, no. 4 (April 26, 2006): 457–74. http://dx.doi.org/10.1017/s0016756805001652.
Повний текст джерелаАнотація:
A late Mesozoic belt of volcanic-intrusive complexes occurs in Southeast China. The Qianlishan granites are distributed in the northwest of the belt. The pluton is composed of porphyritic biotite granite (153 Ma) and equigranular biotite granite (151 Ma) and was intruded by granite-porphyry dykes (144 Ma) and mafic dykes such as lamprophyre and diabase (142 Ma). The granitic rocks, consisting mainly of K-feldspar, plagioclase, quartz and Fe-rich biotite, have SiO2 contents of 72.9–76.9%, and are enriched in alkalis, rare earth elements (REE), high field strength elements (HFSE) and Ga with high Ga/Al ratios, but depleted in Ba, Sr and transition metals. Trace-element geochemistry and Sr–Nd isotope systematics further imply that the Qianlishan granitic magmas were most probably derived by partial melting of Palaeo- to Mesoproterozoic metamorphic lower-crustal rocks that had been granulitized during an earlier thermal event. These features suggest an A-type affinity. The Qianlishan lamprophyre and neighbouring coeval mafic dykes (SiO2 = 47.9–53.8 wt%) have high MgO and compatible element contents. These rocks also have high K2O contents and are enriched in alkalis, light REE, large ion lithophile elements, and depleted in HFSE. They have low initial εNd values and relatively high initial 87Sr/86Sr ratios. We suggest a subduction-modified refractory lithospheric mantle (phlogopite-bearing harzburgite or lherzolite) for these high-Mg potassic magmas. The Qianlishan diabases (SiO2 = 48.4–48.7 wt%) are alkaline and have high TiO2 and total Fe2O3 contents, together with the positive initial εNd value, suggesting derivation from fertile asthenopheric mantle (phlogopite-bearing lherzolite). A back-arc extensional setting, related to subduction of the Palaeo-Pacific plate, is favoured to explain the petrogenesis of the Qianlishan granites and associated mafic dykes. Between 180 and 160 Ma, Southeast China was a continental arc, forming the 180–160 Ma plutons of the late Mesozoic volcanic-intrusive complex belt, and the lower-crust was granulitized. Since 160 Ma the northwestern belt has been in a back-arc extensional setting as a consequence of slab roll-back, resulting in the lithosphere thinning and an influx of asthenophere. The upwelling asthenosphere, on the one hand, induced the local lithospheric mantle to melt partially, forming high-Mg potassic magmas, and on the other hand it underwent decompression melting itself to form alkaline diabase magma. Pulsatory injection of such high-temperature magmas into the granulitized crustal source region induced them to partially melt and generate the A-type magmas of the Qianlishan granitic rocks.
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Xie, Wei, Qing-Dong Zeng, Jin-Hui Yang, Rui Li, Zhuang Zhang, Rui-Liang Wang, and Jin-Jian Wu. "Petrogenesis, W metallogenic and tectonic implications of granitic intrusions in the southern Great Xing’an Range W belt, NE China: insights from the Narenwula Complex." Geological Magazine 159, no. 4 (January 10, 2022): 593–627. http://dx.doi.org/10.1017/s0016756821001175.
Повний текст джерелаАнотація:
AbstractExtensive magmatism in NE China, eastern Central Asian Orogenic Belt, has produced multi-stage granitic plutons and accompanying W mineralization. The Narenwula complex in the southwestern Great Xing’an Range provides important insights into the petrogenesis, geodynamic processes and relationship with W mineralization. The complex comprises granodiorites, monzogranites and granite porphyry. Mafic microgranular enclaves are common in the granodiorites, and have similar zircon U–Pb ages as their host rocks (258.5–253.9 Ma), whereas the W-bearing granitoids yield emplacement ages of 149.8–148.1 Ma. Permian granodiorites are I-type granites that are enriched in large-ion lithophile elements and light rare earth elements, and depleted in high field strength elements and heavy rare earth elements. Both the mafic microgranular enclaves and granodiorites have nearly identical zircon Hf isotopic compositions. The results suggest that the mafic microgranular enclaves and granodiorites formed by the mixing of mafic and felsic magmas. W-bearing granitoids are highly fractionated A-type granites, enriched in Rb, Th, U and Pb, and depleted in Ba, Sr, P, Ti and Eu. They have higher W concentrations and Rb/Sr ratios, and lower Nb/Ta, Zr/Hf and K/Rb ratios than the W-barren granodiorites. These data and negative ϵHf(t) values (–6.0 to –2.1) suggest that they were derived from the partial melting of ancient lower crust and subsequently underwent extreme fractional crystallization. Based on the regional geology, we propose that the granodiorites were generated in a volcanic arc setting related to the subduction of the Palaeo-Asian Ocean, whereas the W-bearing granitoids and associated deposits formed in a post-orogenic extensional setting controlled by the Mongol–Okhotsk Ocean and Palaeo-Pacific Ocean tectonic regimes.
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ZHAI, MINGGUO, JINGHUI GUO, PENG PENG, and BO HU. "U–Pb zircon age dating of a rapakivi granite batholith in Rangnim massif, North Korea." Geological Magazine 144, no. 3 (March 9, 2007): 547–52. http://dx.doi.org/10.1017/s0016756807003287.
Повний текст джерелаАнотація:
Rapakivi granites and several small leucogabbroic and gabbroic bodies are located in the Rangnim Massif, North Korea. The largest batholith in the Myohyang Mountains covers an area of 300 km2 and was intruded into Precambrian metamorphosed rocks. It has a SHRIMP U–Pb zircon weighted mean 207Pb/206Pb age of 1861 ± 7 Ma. The country rocks of rapakivi granites are Neoarchaean orthogneisses and Palaeo-Mesoproterozoic graphite-bearing metasedimentary rocks of granulite facies, and they are similar to those of the rapakivi granites and anorthosites exposed in South Korea and in the North China Craton. We conclude that the three massifs in the Korean Peninsula commonly record an identical Palaeo-Mesoproterozoic anorogenic magmatic event, indicating that they have a common Precambrian basement with the North China Craton.
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Cong, Feng, De-Feng He, Wei-Qiang Ji, Liang Huang, Bo Xiong, Shao-Hua Zhang, and Xiao-Ming Huang. "Petrogenesis of Triassic Caojian A-type rhyolites and associated I-type granites in the southeastern Tibetan Plateau: rejuvenation of crystal mush." Geological Magazine 159, no. 3 (November 2, 2021): 337–56. http://dx.doi.org/10.1017/s0016756821000959.
Повний текст джерелаАнотація:
AbstractThe orogenic process and crustal growth of the Changning–Menglian Palaeo-Tethys orogenic belt in the southeastern Tibetan Plateau is not fully understood. Triassic Caojian rhyolites and granites occur extensively in this orogenic belt and represent important constraints for this issue. This study aims to examine the relationships between the Triassic Caojian rhyolites and granites and to gain a better understanding of their possible petrogenesis. The study used zircon U–Pb geochronology, trace element analyses and Sr–Nd–Hf isotope data to better understand the relationships and possible origin of the rhyolites and granites. Recent zircon U–Pb ages indicated that the Caojian rhyolites were emplaced at 227.2 Ma, whereas age estimates for Caojian granites were slightly older (233.4–236.9 Ma). The Caojian rhyolites are enriched in large-ion lithophile elements and high-field-strength elements, with elevated FeOtot/MgO and Ga/Al ratios. However, they are significantly depleted in Ba, Sr, Eu, P and Ti. These geochemical characteristics indicate that they have an A-type affinity. Furthermore, the Caojian granites comprise biotite monzogranites and granodiorites and show unfractionated composition. Mineralogically, the Caojian granites were found to contain diagnostic I-type minerals such as hornblende. Geochemical data suggest that the petrogenesis of the Triassic Caojian rhyolites is characterized by rejuvenation of crystal mush represented by the Triassic Caojian granites. The necessary thermal input was supplied by mafic magma. This magmatic evolution was likely related to lithospheric delamination and upwelling of the asthenosphere during the Mid- to Late Triassic, forming post-collisional I-type granites and A-type volcanics in the Changning–Menglian Palaeo-Tethys orogenic belt.
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Rappaport, Amy R., Christine D. Palmer, Annie Shen, Claudia X. Dominguez, Meghan G. Hart, Lauren D. Kraemer, Sonia Koulavouth, et al. "Abstract 3578: Optimization of shared neoantigen vaccine design to increase vaccine potency: From bench to bedside and back." Cancer Research 82, no. 12_Supplement (June 15, 2022): 3578. http://dx.doi.org/10.1158/1538-7445.am2022-3578.
Повний текст джерелаАнотація:
Abstract Vaccines targeting neoantigens identified from common tumor driver mutations are of increasing interest as evidence of clinical benefit builds, and opportunities to combine such vaccines with immune modulators are growing. Our individualized neoantigen vaccine (GRANITE) has shown clinical benefit and strong, consistent CD8 T cell induction in patients. We have developed an analogous off-the-shelf product (SLATE) targeting shared neoantigens that offers manufacturing simplicity and faster administration to patients with shared driver mutations. A Phase 1/2 trial of a heterologous prime/boost vaccine regimen using a chimpanzee adenovirus (ChAd) prime and self amplifying mRNA (SAM) boosts (SLATE, NCT03953235) was initiated to assess safety, tolerability, and immunogenicity in patients with advanced cancers. SLATE version 1 encodes 20 unique neoantigens to various shared driver mutations (KRAS, TP53, etc.). Patients were selected if their tumors harbored one of the 20 neoantigens encoded by the vaccine cassette and an HLA Class I allele that presents that neoantigen. Administration of ChAd prime and repeated administration of 30, 100, or 300µg SAM doses were safe and well tolerated in all subjects dosed (n=26), with no evidence of increasing reactogenicity with sequential dosing. Early efficacy signals (molecular responses; one unconfirmed RECIST response) were observed in NSCLC subjects all treated with and progressed on prior anti-PD(L)1. Analysis of T cell responses pre and post immunizations by ex vivo IFNγ ELISpot did not show robust responses to KRAS neoantigens across all patients. However, objective CD8 T cell responses to KRAS antigens post vaccination were detectable after in vitro stimulation, suggesting the induction of low-level KRAS specific T cell responses in vivo. In contrast, HLA-matched responses to TP53 neoantigens encoded by the vaccine were consistently detected via ex vivo ELISpot in these same patients. These data suggests that an immunodominant T cell response to the TP53 mutations may have outcompeted the response to the less immunogenic KRAS mutations restricted and presented by the same HLA in vivo. Differential surface peptide-HLA (pHLA) density may explain these discordant findings, and subsequent targeted mass spectrometry analyses revealed detection of TP53 pHLA complexes at a higher frequency compared to KRAS mutations in single HLA-allele cell lines. Redesigned vaccine cassettes excluding the TP53 epitopes and repeating KRAS epitopes demonstrated increased immune responses (ex vivo IFNγ ELISpot) compared to cassette version 1 in HLA transgenic mice, further supporting the tumor neoantigen immunodominance hierarchy observed in humans dosed with SLATE version 1. A re-designed product (SLATE v2) focusing exclusively on KRAS mutations (G12C, G12D, G12V and Q61H) is currently being assessed in phase 2 in patients with advanced KRAS-driven tumors. Citation Format: Amy R. Rappaport, Christine D. Palmer, Annie Shen, Claudia X. Dominguez, Meghan G. Hart, Lauren D. Kraemer, Sonia Koulavouth, Martina Marrali, Jason R. Jaroslavsky, Charmaine N. Nganje, Ciaran D. Scallan, Sue-Jean Hong, Leonid Gitlin, Monica Lane, Daniel V. Catenacci, Chrisann Kyi, David P. Carbone, Hossein Borghaei, Raphael Rousseau, Andrew Ferguson, Karin Jooss. Optimization of shared neoantigen vaccine design to increase vaccine potency: From bench to bedside and back [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3578.
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YANG, LI-QIANG, YILDIRIM DILEK, ZHONG-LIANG WANG, ROBERTO F. WEINBERG, and YUE LIU. "Late Jurassic, high Ba–Sr Linglong granites in the Jiaodong Peninsula, East China: lower crustal melting products in the eastern North China Craton." Geological Magazine 155, no. 5 (January 26, 2017): 1040–62. http://dx.doi.org/10.1017/s0016756816001230.
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AbstractThe Jurassic Linglong granites, intrusive into the North China Craton (NCC) in eastern China, provide a critical record of the first major episode of lithospheric-scale extension and magmatism in NE China during Mesozoic time. Our U–Pb zircon dating reveals that the Linglong granites were emplaced during 161–158 Ma, shortly after the inception of a shallow subduction of the Palaeo-Pacific plate beneath East Asia during Middle Jurassic time. These granites have high alkali contents (K2O + Na2O = 8–9 wt%), low MgO and Mg no. values and variable Cr–Ni abundances. Their relatively high Ba and Sr concentrations, relatively low heavy rare Earth element (HREE) and strongly fractionated REE patterns characterize them as high Ba–Sr granites. The negative whole-rock εNd(t) values ranging from −22.4 to −10.9 and wide-ranging zircon εHf(t) values of −39.1 to −1.5 suggest that magmas of the Linglong granites were produced by partial melting of a garnet-amphibolite-bearing lower crust of the Jiaobei Terrane and by re-melting of the Triassic ultrahigh-pressure (UHP) metamorphic rocks and alkaline suites of the Sulu Terrane. The occurrence in the granitic rocks of inherited zircons of the Neoarchaean, Palaeoproterozoic, Neoproterozoic, Palaeozoic and Triassic ages suggests that magmas of the Linglong granites interacted with the ancient crust in these terranes during their ascent. Asthenospheric upwelling, induced by the steepening and rapid rollback of the Palaeo-Pacific slab during Late Jurassic time, provided the heat source for the inferred lower crustal melting. Trench migration and thermal weakening of the crust caused extensional deformation and thinning in the eastern part of the NCC.
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ZENG, QING-DONG, YAN SUN, XIAO-XIA DUAN, and JIAN-MING LIU. "U–Pb and Re–Os geochronology of the Haolibao porphyry Mo–Cu deposit, NE China: implications for a Late Permian tectonic setting." Geological Magazine 150, no. 6 (April 26, 2013): 975–85. http://dx.doi.org/10.1017/s0016756813000186.
Повний текст джерелаАнотація:
AbstractNew geochronological data for the Haolibao porphyry Mo–Cu deposit, NE China, yield Permian crystallization zircon U–Pb ages of 278 ± 5 Ma for granite and 267 ± 10 Ma for the granite porphyry that hosts the Mo–Cu mineralization, and four Re–Os molybdenite ages yield an isochron age of 265 ± 3 Ma. These ages disagree with the previous K–Ar age determinations that suggest a correlation of intrusive rocks of the Haolibao area with the Yanshanian intrusive rocks of Cretaceous age. The mineralizations at the Haolibao area may be related to the tectonic–magmatic activity caused by collisional events between the North China Plate and Mongolian terranes during the Permian. The occurrence of the Haolibao plutonic rocks indicates that the Palaeo-Asian-Mongolian Ocean closed during the Permian along the Xilamulun River suture.
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Aptroot, André, Maarten Brand, and Leo Spier. "Fellhanera Viridisorediata, a New Sorediate Species From Sheltered Trees and Shrubs in Western Europe." Lichenologist 30, no. 1 (January 1998): 21–26. http://dx.doi.org/10.1006/lich.1997.0119.
Повний текст джерелаАнотація:
AbstractFelihanera viridisorediata Aptroot, Brand & Spier, a corticolous sorediate species commonly found sterile, is described from fertile material on Juglans glabra in the Netherlands. It was also found with apothecia on, for example, twigs of Vaccinium myrtillus, Lonicera, and other trees. It seems to be common and rapidly spreading in sheltered habitats in Belgium, Germany and the Netherlands, also occasionally on wood, roofs, granite and brick. It is close to other Felihanera species, especially F. seroexpectata and F. viridis, but it differs in the paler soredia, smaller, 1-septate and constricted ascospores and the presence of roccellic acid.
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TIAN, DEXIN, WENCHUN GE, HAO YANG, GUOCHUN ZHAO, and YANLONG ZHANG. "Lower Cretaceous alkali feldspar granites in the central part of the Great Xing’an Range, northeastern China: chronology, geochemistry and tectonic implications." Geological Magazine 152, no. 3 (August 13, 2014): 383–99. http://dx.doi.org/10.1017/s0016756814000387.
Повний текст джерелаАнотація:
AbstractThe Mingshui–Jilasitai–Suolun area, located in the central part of the Great Xing’an Range, is characterized by large volumes of alkali feldspar granites. However, the formation time and tectonic setting of these rocks remains controversial owing to a lack of precise geochronological and detailed geochemical data. In this paper, we report new SIMS U–Pb zircon ages and mineralogical, petrographical and geochemical data for Lower Cretaceous alkali feldspar granites from the Mingshui–Jilasitai–Suolun area. The SIMS zircon dating results indicate that these granites formed at 133.6–135.9 Ma. The mineralogical, petrographical and geochemical data show that these granitic rocks belong to highly fractionated I-type granites. Combined with the regional geology data, we propose that the formation of the Lower Cretaceous alkali feldspar granitic rocks was related to an extension induced by delamination of the lithosphere that arose from subduction of the Palaeo-Pacific plate.
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LI, ZHEN, JIAN-SHENG QIU, and XI-SHENG XU. "Geochronological, geochemical and Sr–Nd–Hf isotopic constraints on petrogenesis of Late Mesozoic gabbro–granite complexes on the southeast coast of Fujian, South China: insights into a depleted mantle source region and crust–mantle interactions." Geological Magazine 149, no. 3 (September 16, 2011): 459–82. http://dx.doi.org/10.1017/s0016756811000793.
Повний текст джерелаАнотація:
AbstractThe Quanzhou (QZ) and Huacuo (HC) gabbro–granite complexes on the southeast coast of Fujian, South China, are important components of a Late Mesozoic calc-alkaline volcanic–plutonic belt in the region. The complexes provide an excellent opportunity to investigate the genetic relationships between acid and basic magmas, and their interactions within the intrusive environment. The complexes are composed mainly of monzogranite and biotite granodiorite in the QZ complex, and biotite granite in the HC complex, with lesser amounts of hornblende gabbro. Zircon U–Pb dating provides consistent crystallization ages of 109 ± 1 Ma and 108 ± 1 Ma for the QZ gabbros and monzogranites, and an age of 111 ± 1 Ma for the HC gabbro, which is contemporaneous with the spatially associated HC granites. Both the mafic and felsic intrusions in these complexes are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs), and are depleted in high-field-strength elements (HFSEs; e.g. Nb and Ta). They show similarly homogeneous Sr–Nd isotopic compositions. All these factors indicate a close genetic relationship between the gabbroic and granitic rocks in the QZ and HC complexes. Although the enriched Sr–Nd isotopic signatures of the QZ and HC gabbros seemingly point to an enriched mantle source (EM-1), they have highly variable zircon Hf isotopic compositions, with εHf(t) values ranging from negative to positive (specifically –4.6 to +6.1 for the QZ gabbros and –4.8 to +11.6 for the HC gabbros). We interpret the parental basic magmas of these gabbros to have received contributions from a depleted mantle source and crustal components. Contributions from such a depleted mantle source resulted in the growth of juvenile basaltic lower crust, the partial melting of which generated the parental felsic magmas of the QZ and HC complexes. Furthermore, based on a synthesis of petrography, geochronology, elemental and isotopic geochemistry and tectonics, we propose that break-off and rollback of the Late Mesozoic subducted Palaeo-Pacific Plate triggered the upwelling of asthenospheric mantle below the coastal area of the South China Block, which induced extension of the overlying continental lithosphere, and finally initiated the large-scale Late Yanshanian magmatism in the study area.
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Jana, Ashim, and Deepak Kumar Sinha. "Geochemistry and tectonic setting for the deposition of IOG siliciclastics at the western margin of Bonai Granite, Singhbhum-Orissa Craton, India." Journal of The Indian Association of Sedimentologists 38, no. 2 (December 31, 2021): 49–62. http://dx.doi.org/10.51710/jias.v38i2.134.
Повний текст джерелаАнотація:
Bagiyabahal and Birtola areas are located in the south-western extension of the Noamundi-Koira Iron Ore Group (IOG) basin. Rock types exposed in the area comprises of siliciclastics and volcanics which occurs unconformably over the basement tonalite-trondhjemite granite-gneiss (Bonai Granite Phase-I). The cover rocks show sheared contact with the porphyritic Bonai Granite Phase-II. The IOG basin margin is suggested to be a part of a ‘volcanic passive margin’ as indicated by the geochemical behaviour of the siliciclastics as well as massive emplacements of mafic intrusives (doleritic sill, dyke and gabbro) and extrusives (basaltic lava flow) along faulted continental blocks. The siliciclastics comprise of U and Au bearing quartz-pebble conglomerate (QPC) and quartzite succession. It was deposited along the western margin of the Bonai granite (phase I) in anoxic conditions as indicated by their low Th/U ratios and presence of detrital uraninite grains. Repeated cycles of sedimentation and volcanism led to the formation of alternate layers of siliciclastics and basic bodies in the area. Major, trace and rare earth elements (REE) geochemical data suggests a semi-humid to humid palaeo-climatic environment of during the deposition in the passive continental margin setting characterized by fault-controlled sedimentation over a rift related faulted continental crust and shelf. Geochemical data suggests chemically weathered provenance dominated by clay minerals. Higher content of U, Th, Au, Cr, REE, platinum group of elements (PGE) and other geochemical ratios suggest a mixed provenance for the deposition of the siliciclastics comprising a predominantly acidic/granitic source possibly from the Bonai Granitic Complex (BGC) along with granite derived reworked quartzose sediments, minor basic and ultrabasic sources of Older Metamorphic Group (OMG). This paper attempts to characterize the geochemical behaviour, tectonic setting and provenance of the siliciclastics of Birtola and Bagiyabahal areas by analyzing drill core and surface samples.
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WEVER, H. E., B. C. STOREY, and P. LEAT. "Peraluminous granites in NE Palmer Land, Antarctic Peninsula: early Mesozoic crustal melting in a magmatic arc." Journal of the Geological Society 152, no. 1 (January 1, 1995): 85–96. http://dx.doi.org/10.1144/gsjgs.152.1.0085.
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ZHU, PINGPING, QIUMING CHENG, ZHENJIE ZHANG, and ZIYE WANG. "Genesis and implications of the Late Jurassic Hailesitai granites in the northern Greater Khingan Range: evidence from zircon U–Pb dating and Hf isotope." Geological Magazine 154, no. 5 (July 11, 2016): 963–82. http://dx.doi.org/10.1017/s0016756816000534.
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AbstractThe tectonic setting and geodynamic model of the Greater Khingan Range (GKR) is highly controversial due to the lack of reliable geological, isotopic and geochronological evidence. In the current study, the Hailesitai pluton, located at the west of the suture between the northern and southern GKR in the east of the Central Asian Orogenic Belt, is selected to address this issue. These granites of the high potassium calc-alkaline series belong to the A1-type granites with typical geochemical characteristics including high contents of Al2O3, extremely low contents of Ti, P, enriched LREE, LILE, depleted HFSE, and a medium Eu negative anomaly. Laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) zircon U−Pb dating indicates that the granites can be divided into two stages: c. 152 and c. 161 Ma. The intrusion of A1-type granites at ~161 Ma implies that intra-plate orogenesis of the northern GKR started at c. 161 Ma at latest. The Hailesitai pluton has relatively homogeneous Hf isotope compositions with a εHf (t) value (+6.0 − +9.0), and two-stage depleted mantle model ages of 579−738 Ma show that the original magma is a mixture of juvenile and crustal source rocks. Extensional collapse of the Mongol−Okhotsk belt between the Siberia block and the northern GKR resulted in the formation of late Jurassic A1-type granites in the northern GKR. The Hailesitai pluton formed in response to post-orogenic extensional collapse of the Mongol–Okhotsk belt, coupled with back-arc extension related to Palaeo-Pacific plate subduction.
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Pankhurst, R. J., M. J. Hole, and M. Brook. "Isotope evidence for the origin of Andean granites." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 79, no. 2-3 (1988): 123–33. http://dx.doi.org/10.1017/s0263593300014164.
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ABSTRACTThe genesis of subduction-related magmas in the Andean region of South America and the Antarctic Peninsula is considered in relation to the Palaeozoic to Cenozoic granitoids belts which are thought to parallel palaeo-coastlines. Their Sr-Nd isotope systematics show a wide range of initial compositions (87Sr/86Sr0 0·7038 to >0·710; εNd, +4 to –10) requiring material input from both depleted mantle and continental crust. In local transects there are consistent trends with time of emplacement, from enriched (crustal) to depleted (mantle) sources, regardless of the sense of migration of magmatism (towards or away from the continent). These trends represent mixing between mantle-derived material and anatectic melts of the lower crust: in each case the crustal end-member reflects the age and isotopic composition of the local deep crustal basement (Precambrian in the easternmost Andes, Palaeozoic in the W and in the Antarctic Peninsula). The depleted end-member could be derived by melting within the subducted oceanic crust, the overlying mantle or previously crystallised mafic underplating. One of the most important factors controlling the mixing process is the angle of subduction, resulting in magma generation under variable tectonic conditions.
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Li, Run-Wu, Xin Zhang, Qiang Shi, Wan-Feng Chen, Yi An, Yao-Shen Huang, Yi-Xin Liu, and Jin-Rong Wang. "Early Permian to Late Triassic tectonics of the southern Central Asian Orogenic Belt: geochronological and geochemical constraints from gabbros and granites in the northern Alxa area, NW China." Geological Magazine 157, no. 12 (April 27, 2020): 2089–105. http://dx.doi.org/10.1017/s0016756820000345.
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AbstractSituated between the North China Craton to the east and the Tarim Craton to the west, the northern Alxa area in westernmost Inner Mongolia in China occupies a key location for interpreting the late-stage tectonic evolution of the southern Central Asian Orogenic Belt. New LA-ICP-MS zircon U–Pb dating results reveal 282.2 ± 3.9 Ma gabbros and 216.3 ± 3.2 Ma granites from the Yagan metamorphic core complex in northern Alxa, NW China. The gabbros are characterized by low contents of Si, Na, K, Ti and P and high contents of Mg, Ca, Al and Fe. These gabbros have arc geochemical signatures with relative enrichments in large ion lithophile elements and depletions in high field strength elements, as well as negative εNd(t) (−0.91 to −0.54) and positive εHf(t) (2.59 to 6.37) values. These features indicate that a depleted mantle magma source metasomatized by subduction fluids/melts and contaminated by crustal materials was involved in the processes of magma migration and emplacement. The granites show high-K calc-alkaline and metaluminous to weakly peraluminous affinities, similar to A-type granites. They have positive εNd(t) (1.55 to 1.99) and εHf(t) (5.03 to 7.64) values. These features suggest that the granites were derived from the mixing of mantle and crustal sources and formed in a postcollisional tectonic setting. Considering previous studies, we infer that the final closure of the Palaeo-Asian Ocean in the central part of the southern Central Asian Orogenic Belt occurred in late Permian to Early–Middle Triassic times.
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Mao, Qigui, Wenjiao Xiao, Brian F. Windley, Minjie Yu, Min Sun, Songjian Ao, and Ji’en Zhang. "Early Permian subduction-related transtension in the Turpan Basin, East Tianshan (NW China): implications for accretionary tectonics of the southern Altaids." Geological Magazine 158, no. 1 (November 14, 2019): 175–98. http://dx.doi.org/10.1017/s0016756819001006.
Повний текст джерелаАнотація:
AbstractThe interaction of the Palaeo-Pacific and Palaeo-Asian Oceans is an enigmatic issue as their temporal and spatial features are controversial. To address this issue, we present a systematic study of large volumes of early Permian volcanic rocks and intrusions developed in the East Tianshan. The represented samples of basaltic andesites and rhyolites yield zircon crystallization ages of 285.1 ± 5.9 Ma and 275.3 ± 1.8 Ma, respectively. The basalts have normal mid-ocean ridge basalt (N-MORB) and arc-related geochemical signatures with high TiO2 contents, negative Rb, Th, U, Nb and Ta anomalies and positive Eu anomalies. Basaltic andesites and andesites have arc-related geochemical characteristics with moderate TiO2 contents and relatively negative Nb, Ta and Ti anomalies, together with slightly negative to positive Eu anomalies. The rhyolites show an affinity with A2-type granite with high SiO2, K2O + Na2O, Fe/Mg, Ga, Zr, Nb, Y, HFSE, REE and Y/Nb levels (>1.2). These geochemical data suggest that the rocks formed in a supra-subduction zone. The presence of high ϵNd(t) values of +4.6 to +8.2 and low (87Sr/86Sr)i (0.70342–0.70591) values indicates that the volcanic rocks originated from a depleted mantle. We propose that oblique subduction with slabs breaking off gave rise to transtension and to the emplacement of large volumes of mantle-derived melts in the early Permian in the East Tianshan, serving as an important record of the subduction zone of the Palaeo-Pacific Ocean.
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Robb, L. J., L. A. Freeman, and R. A. Armstrong. "Nature and longevity of hydrothermal fluid flow and mineralisation in granites of the Bushveld Complex, South Africa." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 91, no. 1-2 (2000): 269–81. http://dx.doi.org/10.1017/s0263593300007434.
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The Lebowa Granite Suite of the Bushveld Complex is a large, 2054 Ma old, A-type batholith, characterised by numerous relatively small magmato-hydrothermal, polymetallic ore deposits. The mineralisation is represented by a three-stage paragenetic sequence: early magmatic Sn-W-Mo-F ores (600°C > T > 400°C), followed by a Cu-Pb-Zn-As-Ag-Au paragenesis (400°C > T > 200°C) and then late-stage Fe-F-U mineralisation (< 200°C). The first stage of mineralisation (typified by the endogranitic Zaaiplaats tin deposit) is related to incompatible trace element concentration during crystal fractionation and subsequent fluid saturation of the magma. Evolution of the late magmatic fluids as they were channelled along fractures, as well as mingling with externally derived connate or meteoric fluids, resulted in the deposition of the second stage of mineralisation (typified by the fracture-related, endogranitic Spoedwel and Albert deposits and the exogranitic, sediment-hosted Rooiberg mine) which is dominated by polymetallic sulphide ores. As the externally derived fluid component became progressively more dominant, oxidation of the polymetallic sulphide assemblage and precipitation of hematite, pitchblende and fluorite occurred generally along the same fracture systems that hosted the earlier sulphide paragenesis.Small hydrothermal zircons trapped along quartz growth zones from the Spoedwel deposit yield a U-Pb concordia age of 1957 ± 15 Ma. Whole-rock Rb-Sr age determinations from the Lebowa Granite Suite fall in the range 1790 ± 114 Ma to 1604 ± 70 Ma and are interpreted to reflect alkali element mobility and isotopic resetting during exhumation of the Bushveld granite. In contrast to thermal modelling which indicates that hydrothermal activity should have ceased within 4 my of emplacement, isotopic evidence suggests that mineralisation was long-lived, but episodic, and that fluid flow events were linked to major periods of Palaeo- and Mesoproterozoic orogenic activity along the margins of the Kaapvaal Craton. During these orogenic episodes, fluid flow was enhanced by tectonically induced fluid over-pressuring and/or exhumation of the Bushveld Complex.
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Ju, Nan, Sen Zhang, Lin-Lin Kou, Hai-Po Wang, Di Zhang, Yu-Chao Gu, and Tong Wu. "Source and Tectonic Setting of Porphyry Mo Deposits in Shulan, Jilin Province, China." Minerals 9, no. 11 (October 26, 2019): 657. http://dx.doi.org/10.3390/min9110657.
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The Shulan area in Jilin Province is a part of the Lesser Xing’an–Zhangguangcai Range polymetallic ore belt, which is an important Cu–Mo ore region of northeast China. The discovery of three large Mo ore deposits (Fu’anbu, Chang’anbu, and Jidetun) highlights its potential for porphyry Mo ore deposits. Here we investigated the tectonic setting and mineralization of Mo ore deposits in the Shulan area, based on comparative study of the Fu’anbu, Chang’anbu, and Jidetun deposits. The ore-controlling structures are NE–SW- and NW–SE-trending faults. The main ore mineral in all three deposits is molybdenite. The ore bodies are all hosted in granites, have a stratiform or lenticular shape, and have strongly altered wall rocks. These observations indicate the Mo deposits in the Shulan area are typical porphyry Mo deposits. All were formed during the early Yanshanian (199.6–133.9 Ma). Biotite adamellites from the Chang’anbu deposit yield a U–Pb age of 182.10 ± 1.20 Ma. Molybdenites from the Fu’anbu and Jidetun deposits have Re–Os isochron ages of 166.9 ± 6.7 and 169.1 ± 1.8 Ma, respectively. Quartz and ore minerals were analysed for H–O and S–Pb isotopes, respectively. The results suggest the ore-forming materials were predominantly of upper-mantle origin, with secondary contributions from the lower crust. The ore-hosting granites have high concentrations of SiO2 (66.67–75.43 wt.%) and Al2O3 (12.91–16.44 wt.%), low concentrations of MgO (0.09–1.54 wt.%), and Ritman index (σ = K2O + Na2O)2/(SiO2 − 43)) ratios of 2.09–2.57. The granites are enriched in large-ion lithophile elements and depleted in high-field-strength elements, and have negative Eu anomalies. The ore-hosting rocks are geochemically similar to granites in northeastern China that were generated in a collisional orogeny. We conclude that early Yanshanian (199.6–133.9 Ma) mantle–crust-derived magmatism caused by the subduction of the Palaeo-Pacific Plate was the main source of Mo deposits in the Shulan area.
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de Wit, M. J., S. Bowring, R. Buchwaldt, F. Ö. Dudas, D. MacPhee, G. Tagne-Kamga, N. Dunn, A. M. Salet, and D. Nambatingar. "Geochemical reconnaissance of the Guéra and Ouaddaï Massifs in Chad: evolution of Proterozoic crust in the Central Sahara Shield." South African Journal of Geology 124, no. 2 (June 1, 2021): 353–82. http://dx.doi.org/10.25131/sajg.124.0048.
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Abstract In 1964, W.Q. Kennedy suggested that the crust of Saharan Africa is different from the rest of Africa. To date, the geologic evolution of this region remains obscure because the age and composition of crystalline basement are unknown across large sectors of the Sahara. Most of Africa comprises Archaean cratons surrounded by Palaeo- to Mesoproterozoic orogenic belts, which together constitute Africa’s three major shields (the Southern, Central and West African Shields), finally assembled along belts of Pan-African rocks. By contrast, central Saharan Africa (5.3x106 km2), an area just over half the size of Europe, is considered either as a Neoproterozoic region constructed of relatively juvenile crust (0.5 to 1.0 Ga), or as an older (North African) shield that was reactivated and re-stabilized during that time, a period commonly referred to as “Pan African”. Here, using U-Pb zircon age determinations and Nd isotopic data, we show that remote areas in Chad, part of the undated Darfur Plateau stretching across ¾ million km2 of the central Sahara, comprise an extensive Neoproterozoic crystalline basement of pre-tectonic gabbro-tonalite-granodiorite and predominantly post-tectonic alkali feldspar granites and syenites that intruded between ca. 550 to 1050 Ma. This basement is flanked along its western margin by a Neoproterozoic continental calc-alkaline magmatic arc coupled to a cryptic suture zone that can be traced for ~2400 km from Tibesti through western Darfur into Cameroon. We refer to this as the Central Saharan Belt. This, in a Gondwana framework, is part of a greater arc structure, which we here term the Great Central Gondwana Arc (GCGA). Inherited zircons and Nd isotopic ratios indicate the Neoproterozoic magmas in the central Sahara were predominantly derived from Mesoproterozoic continental lithosphere. Regional deformation between 613 to 623 Ma marks the onset of late alkaline granite magmatism that was widespread across a much larger area of North Africa until about 550 Ma. During this magmatism, the region was exhumed and eroded, leaving a regional peneplain on which early Palaeozoic (Lower-Middle Cambrian) siliciclastic sediments were subsequently deposited, as part of a thick and widespread cover that stretched across much of North Africa and the Arabian Peninsula. Detrital zircons in these cover sequences provide evidence that a substantial volume of detritus was derived from the central Sahara region, because these sequences include ‘Kibaran-age’ zircons (ca. 1000 Ma) for which a source terrain has hitherto been lacking. We propose that, in preference to calling the central Sahara a “ghost” or “meta” craton, it should be called the Central Sahara Shield.
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Song, Dongfang, Wenjiao Xiao, Brian F. Windley, and Chunming Han. "Carboniferous to Early Triassic magmatism and accretion in Alxa (NW China): implications for accretionary orogenesis of the southern Altaids." Journal of the Geological Society 177, no. 5 (May 6, 2020): 997–1012. http://dx.doi.org/10.1144/jgs2020-046.
Повний текст джерелаАнотація:
Alxa occupies a crucial position between the Tianshan–Beishan orogen to the west and the Solonker suture to the east and is important in our understanding of the accretionary orogenesis of the southern Altaids. To unravel the tectonic history of the Alxa region, we undertook an integrated study of the field geology, geochemistry and geochronology of magmatic rocks and an accretionary complex. Six granites and one rhyolite from the Zhusileng–Hangwula arc show a peraluminous, high-K calc-alkaline composition and one gabbro is tholeiitic. They show patterns rich in incompatible elements and negative Nb–Ta anomalies on primitive mantle-normalized trace element spider diagrams. Laser ablation inductively coupled plasma mass spectrometry zircon U–Pb dating reveals 348–329 and 267–250 Ma magmatic events. These data indicate that the Zhusileng–Hangwula arc was a Japan-type island arc from the late Paleozoic to Early Triassic. The Engger Us mélange comprises pillow basalts with a normal-type mid-ocean ridge basalt composition, tuffs, cherts, siliceous mudstones, limestones and turbidites, which are tectonically juxtaposed by a block-in-matrix structure. This mélange is interpreted as a Carboniferous–Permian accretionary complex. These new data, combined with previous studies, confirm that the Palaeo-Asian Ocean subducted bidirectionally in the Alxa region in the Carboniferous–Early Triassic. A consistent divergent subduction system existed from Alxa to Solonker before the terminal closure of the Palaeo-Asian Ocean in the Mid- to Late Triassic.Supplementary material: Major and trace element data and zircon U-Pb age results of all the samples are available at: https://doi.org/10.6084/m9.figshare.c.4962230
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Dilek, Yildirim, and Limei Tang. "Magmatic record of the Mesozoic geology of Hainan Island and its implications for the Mesozoic tectonomagmatic evolution of SE China: effects of slab geometry and dynamics in continental tectonics." Geological Magazine 158, no. 1 (December 10, 2020): 118–42. http://dx.doi.org/10.1017/s0016756820001211.
Повний текст джерелаАнотація:
AbstractOur field-based geochemical studies of the Triassic, Jurassic and Cretaceous granitoids on Hainan Island indicate that their magmas had different geochemical affinities, changing from alkaline in the Triassic through ocean island basalt (OIB) in the Jurassic, to calc-alkaline in the Cretaceous. We show that these changes in the geochemical affinities of the Mesozoic granitoids on Hainan and in SE China reflect different melt sources and melt evolution patterns through time. Our new geodynamic model suggests that: (1) Triassic geology was controlled by flat-slab subduction of the palaeo-Pacific plate beneath SE China. This slab dynamics resulted in strong coupling between the lower and upper plates, causing push-over tectonics and contractional deformation in SE China. Flat subduction-induced edge flow and aesthenospheric uprising led to the production of high-K granites, syenites and mafic rocks. (2) Slab foundering, accelerated subduction rates and subduction hinge retreat in the Early Jurassic caused rapid rollback of the downgoing slab. Strong decoupling of the upper and lower plates resulted in pull-away tectonics, producing extensional deformation in SE China. Decompression melting of the upwelling aesthenosphere produced OIB-type melts, which interacted with the subcontinental lithospheric mantle (SCLM) to form A- and I-type granitoids. (3) Segmentation of the palaeo-Pacific plate in the Early Cretaceous resulted in steeply dipping slabs and their faster rollback, facilitating lithospheric-scale extension and oceanward migration of calc-alkaline magmatism. This extensional deformation played a significant role in the formation of metamorphic core complexes, widespread crustal melting and development of a Basin and Range-type tectonics and landscape evolution in SE China.
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KLEMENS, WERNER P., and W. M. SCHWERDTNER. "Emplacement and deformation of granite pegmatite dykes in a mid-crustal regime of late-orogenic extension, southwest Grenville Province, Ontario, Canada." Geological Magazine 134, no. 3 (May 1997): 287–95. http://dx.doi.org/10.1017/s0016756897007048.
Повний текст джерелаАнотація:
The horizontal opening of vertical fractures during emplacement of pegmatite-dyke swarms is an important mid-crustal mechanism of large-scale horizontal extension. This is documented in the south-western Grenville Province, a deeply eroded part of the collisional Grenville orogen. In the Georgian Bay region of central Ontario, Grenville gneisses host c. 990 Ma old, angular dykes which attest not only to horizontal extension but also to vertical thinning. The original dilation dykes probably varied in strike and were statistically vertical. However, many dykes had subhorizontal or inclined segments that were oblique or quasi-concordant to the gneissic foliation in the host rocks. The number of dykes exposed per 0.25 km2 varies on the scale of a few kilometres, and this is indicative of heterogeneous late orogenic extension of the Grenville gneisses. The apparent absence of regional gradients of peak palaeo-pressure, at the present erosion level, suggests that the extension was horizontal and initially unaccompanied by vertical contraction of the host gneisses. Subsequent buckling of the pegmatite dykes led to gentle, open or close folds with vertical enveloping surfaces. The geometric effects of gentle buckling of pegmatite dykes can be difficult to recognize in the field, especially where the late-stage vertical thinning is relatively weak. Among the geometric indicators of buckle-shortened dykes, the characteristic deflection (‘fanning’) of coplanar, inherited folia in gneissic host rocks is most sensitive. Systematic changes in the local degree of vertical shortening are indicative of heterogeneous vertical thinning, and may be associated with pull-apart structures at the horizontal scale of several kilometres.
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WANG, YU, ZHAOHUA LUO, M. SANTOSH, SHUZHI WANG, and NA WANG. "The Liuyuan Volcanic Belt in NW China revisited: evidence for Permian rifting associated with the assembly of continental blocks in the Central Asian Orogenic Belt." Geological Magazine 154, no. 2 (February 3, 2016): 265–85. http://dx.doi.org/10.1017/s0016756815001077.
Повний текст джерелаАнотація:
AbstractThe basaltic pillow lavas in the Liuyuan region of NW China, considered to be part of an ophiolitic suite, have been central to the models on tectonic setting, evolution and timing of the final closure of the Palaeo-Asian Ocean. New field evidence on the sedimentary units associated with the basalts reveals comparable sequences in the northern and southern flanks of the Liuyuan Volcanic Belt with coarse to fine sediments from periphery to the centre. The dacites and rhyolites formed coevally with the pillow basalts. The pillow basalts are interlayered with lacustrine sandstone, claystone and clayey lake deposits. Detrital zircons from these sediments yield zircon U–Pb ages of 291–285 Ma. Andesites, dacites and rhyolites from the basaltic sequence yield U–Pb ages of 280–277 Ma, similar to the 282–280 Ma ages of gabbros that intrude the pillow lavas. All these rocks cover the 460–440 Ma granite and greenschist basement and have been intruded by gabbros of c. 272 Ma age, with subsequent (230–227 Ma) north–south contractional thrusting and folding. The data from our study are incompatible with the existing models that consider the basalts as part of an ophiolitic suite. Along the northern continental margin of China from west to east, the Tarim, Dunhuang-Alxa and North China cratonic areas all show evidence for regional extension through rifting during early–middle Permian time. These rift features and basaltic eruptions occurred coevally with the assembly of various microcontinental blocks against the Siberian craton at c. 300–250 Ma, synchronous with amalgamation of the Central Asian Orogenic Belt (CAOB) on the northern side of the Liuyuan Rift. These events were also broadly synchronous with formation of the global supercontinent Pangea.
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Zhang, Qichao, Yan Liu, Zhenhan Wu, He Huang, Kan Li, and Qing Zhou. "Late Triassic granites from the northwestern margin of the Tibetan Plateau, the Dahongliutan example: petrogenesis and tectonic implications for the evolution of the Kangxiwa Palaeo-Tethys." International Geology Review 61, no. 2 (January 8, 2018): 175–94. http://dx.doi.org/10.1080/00206814.2017.1419444.
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Zheng, Xue, Baruch Spiro, and Zuozhen Han. "Comparison of Geochemical and Mineralogical Characteristics of Palaeogene Oil Shales and Coals from the Huangxian Basin, Shandong Province, East China." Minerals 10, no. 6 (May 29, 2020): 496. http://dx.doi.org/10.3390/min10060496.
Повний текст джерелаАнотація:
Coal and oil shale are both organic matter-rich sedimentary rocks. However, their sources of organic matter and their depositional environments are different. The present study focuses on the Palaeogene Lijiaya Formation sequence in the Huangxian Basin, Shandong Province, East China, which has oil shales showing marine geochemical indicators overlain by coals indicating marine regression. We investigated the C1 coal seam and underlying OS2 oil shale layers, compared their geochemical and mineralogical characteristics, clarified the details of their constituents, in order to elucidate the features of their sources, their depositional environments, and the post depositional processes in the context of the geological evolution of the basin. The Al2O3/TiO2 (18.1–64.9) and TiO2/Zr ratios (28.2–66.5) in the C1 coals and OS2 oil shales, respectively, suggest a felsic to intermediate source, and the Mesozoic granite on the South of Huangxian Fault may be one of the provenances of these sediments. The low sulphur content (0.53–0.59%) and low Sr/Ba ratios (0.32–0.67) suggest a freshwater depositional environment for the C1 coals. In contrast, the higher total sulphur contents (0.60–1.44%), the higher Sr/Ba ratios (0.31–1.11%), and the occurrence of calcareous shells, indicate seawater intrusions during deposition of the oil shales. The V/Ni, V/(V + Ni), and V/Cr ratios of the OS2 oil shale suggest oxic to suboxic conditions with a distinct change in palaeo-redox between the lower and upper parts of OS2 seam. The high boron contents in C1 coals (average, 504 ppm) is related to the high content of analcime (with the correlation coefficient of 0.96), and the high concentration of boron was attributed to a secondary enrichment by epigenetic hydrothermal solutions. The occurrence of idiomorphic-authigenic albite in association with analcime and quartz in veins in the coals suggests that albite is a product of a reaction between analcime and silica, both of volcanic origin. The reaction takes place at about 190 °C, indicating that the area was affected by hydrothermal fluids.
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Yang, Jinbao, Zhidan Zhao, Qingye Hou, Yaoling Niu, Xuanxue Mo, Dan Sheng, and Lili Wang. "Petrogenesis of Cretaceous (133–84 Ma) intermediate dykes and host granites in southeastern China: Implications for lithospheric extension, continental crustal growth, and geodynamics of Palaeo-Pacific subduction." Lithos 296-299 (January 2018): 195–211. http://dx.doi.org/10.1016/j.lithos.2017.10.022.
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Mathew, Shijo, Pritam Karmakar, Rajeev Bidwai, S. K. Sharma, Navin Goyal, and D. K. Sinha. "Provenance and depositional characteristics of Lathi Formation in southern part of Jaisalmer Basin: Implications for exploration of sandstone type uranium mineralization." Journal of The Indian Association of Sedimentologists 38, no. 1 (June 30, 2021): 41–50. http://dx.doi.org/10.51710/jias.v38i1.155.
Повний текст джерелаАнотація:
The lower Jurassic Lathi Formation covers about 900 sq. km area and forms the lowermost unit of Jaisalmer Basin of western Rajasthan. Lithologically the Lathi Formation comprises of conglomerate, sandstone, siltstone, shale and mudstone. The sandstones are generally medium- to coarse-grained, moderately sorted and show variation in colour, grain-size and texture. Petrographic studies indicate a mixed provenance for the Lathi sandstone. On the basis of geochemical data, theses sandstones are classified into sub-arkose, litharenite and sub-litharenite. Palaeo-weathering indices such as CIA (80.45), CIW (85.23) and PIA (84.23) suggest moderate to high degree of chemical weathering of the source area, intermediate and felsic igneous provenance, under humid to semi-humid climatic conditions. Further, the geochemical data indicate the sedimentation in a passive continental margin setting. The Bouguer gravity image clearly depicts the north westward slope of the basement. Modelling studies of the gravity data revealed average depth to the basement as 800m, 400m and 250m respectively in northwest, central and southeastern parts of the surveyed area. Exploration activities by Atomic Minerals Directorate for Exploration and Research have resulted in location of several uranium anomalies in the Lathi Formation. Lathi Formation is characterised by many favourable parameters such as fertile provenance, arkosic sandstones intercalated with shale/mudstone, reduced sedimentary facies with carbonaceous matter, lignite and pyrite deposited in continental to marginal marine environment. Malani Igneous Suit and metamorphic rocks constitute the basement for Jaisalmer Basin. Malani rhyolites and granites are fertile source of uranium, containing 6.7 ppm and 9.2 ppm average and intrinsic uranium respectively. Presence of carbonaceous matter and pyrite bearing sandstones, indicative of reducing environment at depth below water table (R.L. 150 m), was reported during subsurface exploration in Lathi sandstone which is a favourable condition for Lathi sediments to host uranium mineralization.
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WANG, YU, CHIN-HO TSAI, LIYUN ZHOU, YAN QIU, and GUIHUA SUN. "Reassessment of the Mesozoic metasedimentary rocks and tectonic setting of Taiwan and the adjacent continental margin of eastern Asia." Geological Magazine 154, no. 5 (August 30, 2016): 1127–54. http://dx.doi.org/10.1017/s0016756816000741.
Повний текст джерелаАнотація:
AbstractIt remains unclear whether a crystalline basement exists in SE China (including Taiwan), whether the formation of the Tananao metamorphic belt in Taiwan was linked to subduction of the Palaeo-Pacific Plate, and whether the source rocks of the sedimentary sequences in the metamorphic belts are late Mesozoic or Palaeozoic in age. Field investigations and zircon age data in the present study indicate that there is no pre-Palaeozoic gneiss (crystalline basement) in Taiwan (although orthogneisses were produced during deformation and metamorphism of Mesozoic granites), and investigations of the metasediments show that the sedimentary sequences in the Tailuko and Yuli belts are similar. Moreover, LA-ICP-MS dating of detrital zircons from the Pingtan–Dongshan belt in Fujian Province yields a cluster of 206Pb–238U ages at ~ 210–190 Ma, and the Tailuko and Yuli belts in Taiwan have similar clusters of detrital zircon ages at 200 Ma, 160 Ma, 120 Ma and 110 Ma, as well as a later overprinting caused by arc–continent collision. The cathodoluminescence images and trace-element characteristics of the zircons show that they were originally magmatic in origin. This finding, combined with the Hf isotope data, indicates that the sources of sediments in the Tananao belt (Tailuko and Yuli belts) were relatively close to an active continental margin, and that both the Tailuko and Yuli belts have similar sedimentary sources. From the margin of the Chinese mainland to Taiwan, the metasediments seem to represent a continuous sequence of deposits ranging in age from Jurassic to Cretaceous, but with the sediments becoming progressively younger towards the east. It can be inferred that the sediments in the Tailuko and Yuli belts were continental-shelf sequences with sources in SE China.
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LORENZ, HENNING, DAVID G. GEE, and MARTIN J. WHITEHOUSE. "New geochronological data on Palaeozoic igneous activity and deformation in the Severnaya Zemlya Archipelago, Russia, and implications for the development of the Eurasian Arctic margin." Geological Magazine 144, no. 1 (November 9, 2006): 105–25. http://dx.doi.org/10.1017/s001675680600272x.
Повний текст джерелаАнотація:
The Severnaya Zemlya Archipelago, located close to the continental edge of the Kara Shelf in the Russian high Arctic, represents, together with northern Tajmyr, the exposed Neoproterozoic and Palaeozoic part of the North Kara Terrane. This terrane has been interpreted as an independent microcontinent or part of a larger entity, such as Arctida or Baltica, prior to collision with Siberia in Late Carboniferous time. A major stratigraphic break, the Kan'on (canyon) River Unconformity, separates folded Late Cambrian from Early Ordovician successions in one area, October Revolution Island. New geochronological U–Th–Pb ion-microprobe data on volcanic and intrusive rocks from this island constrain the age of an important magmatic episode in the earliest Ordovician. A tuff, in association with Tremadocian fossils, overlying the Kan'on River Unconformity, has been dated to 489.5 ± 2.7 Ma. The youngest rocks beneath the unconformity are of the Peltura minor Zone, and the latter has been dated previously, in western Avalonia, to 490.1+1.7−0.9 Ma. Thus, little time is available for the tectonic episode recorded by the unconformity, and the similarities in radiometric dates may indicate problems with the correlation of faunal markers for the Cambrian–Ordovician boundary across palaeo-continents. The other extrusive and intrusive rocks which have been related to Early Ordovician rifting in the Severnaya Zemlya area yield ages from 489 Ma to 475 Ma. An undeformed granite, cutting folded Neoproterozoic successions on neighbouring Bol'shevik Island has been dated to 342 ± 3.6 Ma and 343.5 ± 4.1 Ma (Early Carboniferous), in accord with evidence elsewhere of Carboniferous strata unconformably overlying the folded older successions. This evidence conflicts with the common interpretation that the structure of the Severnaya Zemlya Archipelago originated during the collision of the North Kara Terrane with Siberia in Late Carboniferous time. An alternative interpretation is that Severnaya Zemlya was located in the Baltica foreland of the Caledonide Orogen and that the eastward-migrating deformation of the foreland basin reached the area of the archipelago in latest Devonian to Early Carboniferous time. This affinity of the North Kara Terrane to Baltica is further supported by 540–560 Ma xenocrysts in Ordovician intrusions on October Revolution Island, an age which is characteristic of the Timanide margin of Baltica.
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FU, LEBING, JUNHAO WEI, TIMOTHY M. KUSKY, HUAYONG CHEN, JUN TAN, YANJUN LI, LINGJUN KONG, and YONGJIAN JIANG. "Triassic shoshonitic dykes from the northern North China craton: petrogenesis and geodynamic significance." Geological Magazine 149, no. 1 (March 9, 2011): 39–55. http://dx.doi.org/10.1017/s0016756811000173.
Повний текст джерелаАнотація:
AbstractZircon U–Pb ages, major and trace element geochemistry and Sr, Nd and Pb isotope compositions of diorite and diorite porphyry dykes from the Jinchanggouliang (JCGL) gold ore field on the northern margin of the North China craton (NCC) were studied to investigate their sources, petrogenesis and geodynamic significance. LA-ICP-MS zircon U–Pb dating reveals three major age groups of 2500 Ma (n = 2), 253 ± 7 Ma (n = 5) and 227 ± 1 Ma (n = 9). The inherited ages of 2500 Ma, contemporary with the Archaean NCC continental growth, imply that crustal material was involved in the magma source. The igneous zircons with a concordia age of 227 ± 1 Ma may record the emplacement age of the JCGL dykes. Both diorite and diorite porphyry exhibit a wide range of SiO2 and MgO contents and are characterized by high concentrations of Na2O+K2O and Al2O3, and low abundances of P2O5 and TiO2. They are enriched in large ion lithophile elements and light rare earth elements without significant Eu anomalies, and depleted in high-field-strength elements; all are categorized as shoshonitic rocks. All samples show a narrow range of Sr isotope compositions with initial 87Sr/86Sr ratios from 0.70394 to 0.70592, variable εNd(t) values (1.1 to −12.0) and TDM2 ages of 913–1972 Ma. Their Pb isotope compositions form continuous variation trends and plot in the fields between enriched mantle 1 (EM1) and lower continental crust (LCC). The above results suggest that the JCGL dykes studied could have been derived from mixing of lower crust, lithospheric mantle of the NCC and ascending asthenospheric melt in a post-orogenic extensional geodynamic setting. These shoshonitic dykes, together with the geochronological data of regional ENE-trending retrograded eclogites, ophiolites, continental arc magmatic belt, A-type granite, alkaline intrusions and metamorphic core complex from the northern NCC and Central Asian Orogenic Belt (CAOB) suggest that closure of the Palaeo-Asian Ocean (i.e. stage of pre-collision to collision) had completed during latest Permian to earliest Triassic time, and that the CAOB was subsequently tectonically dominated by post-orogenic extensional regimes. The involvement of asthenospheric melt in the magma source implies that the sub-continental lithospheric mantle (SCLM) of the NCC had been modified, and the onset of lithospheric destruction and thinning beneath the northern NCC may have occurred in Middle–Late Triassic time as a result of post-orogenic subducting slab detachment and lithospheric delamination.
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Yang, Jinbao, Zhidan Zhao, Qingye Hou, Yaoling Niu, Xuanxue Mo, Dan Sheng, and Lili Wang. "Corrigendum to “Petrogenesis of Cretaceous (133–84 Ma) intermediate dykes and host granites in southeastern China: Implications for lithospheric extension, continental crustal growth, and geodynamics of Palaeo-Pacific subduction” [Lithos 296–299 (2018) 195–211]." Lithos 300-301 (February 2018): 378–79. http://dx.doi.org/10.1016/j.lithos.2017.12.017.
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Turner, Simon, Trevor Ireland, John Foden, Elena Belousova, Gerhard Wörner, and Jelte Keeman. "A comparison of granite genesis in the Adelaide Fold Belt and Glenelg River Complex using U-Pb, Hf and O isotopes in zircon." Journal of Petrology, October 11, 2022. http://dx.doi.org/10.1093/petrology/egac102.
Повний текст джерелаАнотація:
Abstract We present new U-Pb ages and Hf and O isotope data for zircon from I-, S- and A-type granites from both the western and eastern edges of the Delamerian Orogen in southeastern Australia. The I-type Tanunda Creek Gneiss contains zircon populations of 507 ± 4 Ma and 492 ± 6 Ma inferred to reflect igneous and metamorphic ages, respectively. The I-type Palmer Granite yielded an age of 509 ± 3 Ma and the Port Elliot S-type Granite has a magmatic age of 508 ± 7 Ma. Inherited zircon in these granites range from 1092 to 3343 Ma, probably derived from assimilation of Adelaide Group sediments. The Murray Bridge A-type Granite is 490 ± 2 Ma in age and lacks inherited zircon. In the Glenelg River Complex, a S-type migmatite from near Harrow contains a complex zircon population. It is most likely ~ 500 Ma in age and has inherited zircon of 550-700, 1000-1100 and 2437 Ma, hence matching those from the Kanmantoo Group. From this and detrital zircons ages we infer that only the Kanmantoo Group extends across the Murray Basin into the Glenelg River Complex. The Wando Tonalite and Loftus Creek I-type granites yielded ages of 501 ± 2 Ma and 486 ± 3 Ma, respectively. Zircon from the Dergholm Granite has suffered Pb loss and the best age estimate for this granite is 488 ± 5 Ma. Combining all the granite data together, εHft and δ18O in the magmatic zircon range from 5.6 to -10.3 and from 5.8 to 8.1, respectively, and are well correlated. The zircon indicate the same temporal and compositional evolution of granitic petrogenesis across ~ 300 km of strike, reaffirming the notion that these terranes form part of the same orogen. Westward-directed subduction caused orogenic thickening, heating and increasing amounts of crustal contribution. This was followed by convective thinning of the thickened mantle lithosphere and a return to more primitive magmas lacking significant crustal contributions. It contrasts significantly with inferred granite petrogenesis and tectonic style in the younger Lachlan and New England Fold Belts further east that were not built upon extended cratonic lithosphere.
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Zhao, Xiaochen, Chiyang Liu, Jianqiang Wang, Yazhuo Niu, Lei Huang, Shaohua Zhang, Fangpeng Du, et al. "Petrogenesis and tectonic implications of the early Mesozoic granitoids in the northern Alxa region, Central Asian Orogenic Belt." Geological Magazine, December 21, 2022, 1–22. http://dx.doi.org/10.1017/s0016756822001157.
Повний текст джерелаАнотація:
Abstract The northern Alxa region is located in the central segment of the southern Central Asian Orogenic Belt. Many controversies and deficiencies still exist regarding the magma source characteristics, petrogenesis and tectonic regimes during the late Palaeozoic – early Mesozoic period within this region. This study presents whole-rock compositions and zircon U–Pb and Lu–Hf isotopic data for three early Mesozoic I- and A-type granitic plutons occurring in the northern Alxa region. The Haerchaoenji and Chahanhada I-type granitoids yielded zircon 206Pb–238U ages of 245 ± 5 Ma and 245 ± 2 Ma, respectively. The variable positive zircon ϵHf(t) values between +1.8 and +11.8, with young TDM ages of 425–837 Ma, indicate that these I-type granitoids were mainly derived from juvenile crustal materials. The Wulantaolegai pluton has a zircon 206Pb–238U age of 237 ± 2 Ma and is classified as having high-K calc-alkaline A-type affinity. Furthermore, the positive zircon ϵHf(t) values of the Wulantaolegai granite range from +3.3 to +8.7 with young TDM ages of 545–778 Ma, suggesting the involvement of a juvenile crustal source as well. Furthermore, the major-element compositions of the Chahanhada and Wulantaolegai granites suggest the input of metasedimentary components. Geochemically, the Haerchaoenji and Chahanhada I-type granitoids show an arc affinity, while the Wulantaolegai granite exhibits a post-collisional affinity. However, with regional data, we suggest that the Haerchaoenji and Chahanhada I-type granitoids were also emplaced in a post-collisional setting, and the arc affinity was probably inherited from recycled subduction-related materials. These lines of evidence obtained in this study enable us to argue that the Palaeo-Asian Ocean in the central segment of the Central Asian Orogenic Belt closed before Middle Triassic time.
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Liang, YaYun, Wenhui Guo, Yao Ma, and Enquan Zhao. "Geochemical Evidence for Thickening and Thinning of Lower Crust beneath the Jiaodong Peninsula: Implications for Late Mesozoic Destruction of the Eastern North China Craton." Lithosphere 2020, no. 1 (November 9, 2020). http://dx.doi.org/10.2113/2020/8831664.
Повний текст джерелаАнотація:
Abstract The eastern North China Craton (NCC) has been recognised as undergoing cratonic destruction during the Mesozoic; however, the mechanism of its destruction is still unclear. The main difference between the proposed models is whether the lower continental crust (LCC) underwent thinning. In this study, we conducted comprehensive analyses of Late Mesozoic felsic intrusive rocks, including Late Jurassic granites (166–146 Ma), Early Cretaceous granodiorites (136–123 Ma), and latest Early Cretaceous granites (123–108 Ma) from the Jiaodong Peninsula, located on the southeastern margin of the NCC. These rocks allowed us to investigate variations in the LCC thickness in this region and to further discuss the destruction mechanism of the eastern NCC. Here, temporal variations in crustal thickness can be tracked using whole-rock La/Yb ratios of the felsic intrusive rocks. Our study shows that the continental crust in the eastern NCC thickened during the Late Jurassic (>40 km) due to compression and the westward subduction of the Palaeo-Pacific Ocean lithosphere beneath the NCC since the Early Jurassic. The continental crust further thickened during the Early Cretaceous, caused by the steepening of the subducting slab after ~144 Ma that produced crustal underplating of mantle-derived melts in an extensional setting. However, the continental crust thinned (20–40 km) during the latest Early Cretaceous, caused by the rollback of the subducting slab after ~123 Ma. The geochemical compositions of three stages of felsic intrusions also suggest that the regional tectonic stress that affects the eastern NCC altered from a compressional to an intraplate extensional environment after ~144 Ma. Thus, the Late Mesozoic destruction of the eastern NCC and its accompanying magmatism were controlled by prolonged thermomechanical-chemical erosion due to low-angle subduction, steepening, and rollback of the Palaeo-Pacific Oceanic lithosphere.
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Skaryatin, Mikhail V., Ekaterina A. Bulgakova, Vladimir E. Verzhbitskiy, Nikolay A. Malyshev, Viktor V. Obmetko, Alexey A. Borodulin, and Bulat I. Ikhsanov. "The South Chukchi-Hope Tectono-Sedimentary Element." Geological Society, London, Memoirs, March 18, 2021, M57–2019–14. http://dx.doi.org/10.1144/m57-2019-14.
Повний текст джерелаАнотація:
AbstractThe South Chukchi-Hope Tectono-Sedimentary Element rests on the Neocomian folded basement formed as a result of the South Anyui palaeo-ocean closure. The interpretation of 2D seismic data as well as results of onshore structural field studies and dating of post-kinematic granite plutons suggest post-collisional extensional/transtensional regimes, potentially driving development of the South Chukchi-Hope Basin. The orogenic collapse occurred during the Aptian-Albian and followed by continued poly-phase extensional/transtensional regime during the Late Cretaceous and Cenozoic. Depositional environments in the basin were most likely non-marine in the Cretaceous and Early Tertiary and marine from the Late Oligocene (?) - Miocene onwards. Three onshore wells in the adjacent depocentres penetrated Tertiary sediments and have had gas shows from two sites. Geochemical surveys registered anomalies of thermogenic and biogenic methane and in some instances higher molecular ethane to penthane gases in sea-bottom sediments above gas chimneys observed on seismic lines. The tectono-sedimentary element is characterized by a very high present-day thermal gradient of up to 48 deg. C/km recorded in the Alaskan wells and was previously considered to be gas-prone.
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Pavei, Diego Dias, Marcos César Pereira Santos, Vitor Hugo Rosa Biffi, Carla Bica, Marlon Borges Pestana, and Juliano Bitencourt Campos. "Estratigrafia e zooarqueologia de cerritos de Santa Vitória do Palmar, Rio Grande do Sul. Novos dados sobre o sítio RS-158: Alberto Talayer." Boletim do Museu Paraense Emílio Goeldi. Ciências Humanas 17, no. 2 (2022). http://dx.doi.org/10.1590/2178-2547-bgoeldi-2021-0009.
Повний текст джерелаАнотація:
Resumo Este estudo visa apresentar os resultados estratigráficos e zooarqueológicos do sítio arqueológico RS-158: Alberto Talayer, localizado no município de Santa Vitória do Palmar, Rio Grande do Sul. O objetivo é revisar as informações estratigráficas das campanhas de escavação dos anos 1970 e apresentar novos resultados zooarqueológicos e estratigráficos da escavação realizada em 2014. Os dados estratigráficos indicam que as ocupações desse sítio possuem uma sequência com mais de 2 metros de profundidade, com cinco camadas e indícios de diferentes níveis de ocupação (níveis arqueológicos IIa e IIIa), marcadas por períodos pré-cerâmico e cerâmico (tradição Vieira). Nos dois montículos que compõem o sítio arqueológico RS-158, a caça de mamíferos teria sido a principal atividade econômica, se destacando com a abundância do veado-campeiro. O problema relativo à sobreposição de diferentes níveis arqueológicos em uma estrutura antrópica encontra nesse estudo um contributo direto com o estabelecimento de variados níveis de ocupação e sua correlação entre os diferentes montículos. Assim, o sítio apresenta características específicas do ambiente no qual se localiza, com interações com os ecossistemas pampeanos, como campos sulinos, rios e lagoas.
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Chen, Chang-Jian, and Shuan-Hong Zhang. "Sources and oxidation state of the Permian arc magmatic rocks of SW Jilin Province in the eastern Central Asian Orogenic Belt: evidence from Li, Hf isotopes and oxygen fugacity." Geological Magazine, September 27, 2022, 1–19. http://dx.doi.org/10.1017/s0016756822000711.
Повний текст джерелаАнотація:
Abstract The late Palaeozoic continental-arc magmatic rocks in the Gongzhuling area are located in the Liaoyuan Accretionary Belt. Here we present new zircon U–Pb ages, whole-rock major- and trace-element compositions, Li and zircon Hf isotopic compositions and oxygen fugacity of these rocks with an aim to constrain the lithium isotopic composition of the source region and origin of the magmas. These rocks were formed during 269–258 Ma in middle–late Permian time. The dioritic rocks were formed through mixing processes, with the mafic melts originating from a metasomatized mantle wedge and the felsic melts from the lower crust of a Neoproterozoic arc. The mantle wedge has been metasomatized by Li-rich fluids derived from subducted oceanic crust, as indicated by the δ7Li values of +0.4 ‰ to +3.5 ‰ and positive ϵHf(t) values (+0.7 to +13.1). Redox-sensitive Ce in the zircons indicates the fO2 of the magmas to be low to intermediate (FMQ−2.2 to FMQ+2.6; FMQ is the fayalite–magnetite–quartz redox buffer), precluding large-scale porphyry Cu–Mo mineralization. The middle–late Permian magmatic rocks represent the terminal magmatic record of the subduction of the Palaeo-Asian oceanic crust, meaning that the final closure of the Palaeo-Asian Ocean in the eastern Central Asian Orogenic Belt occurred at the end of the Permian Period. Recent identification of Mesoproterozoic (c. 1400 Ma) granites suggests some Palaeoproterozoic crustal fragments still exist in the Liaoyuan Accretionary Belt, but only in a small amount; therefore, it is concluded that the crustal growth of the Liaoyuan Accretionary Belt occurred mainly during the Neoproterozoic period.
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Das, Satabdi, Deepak K. Sinha, Sanjoy Sanyal, Subrata Karmakar, Biswajit Panigrahi, Sirina Roy Choudhury, Shyamal Sengupta, and Pulak Sengupta. "Petrogenesis of a nepheline syenite from parts of the Chotanagpur Granite Gneissic Complex: implications for Neoproterozoic crustal extension in the East Indian Shield." Geological Magazine, April 28, 2022, 1–28. http://dx.doi.org/10.1017/s0016756822000140.
Повний текст джерелаАнотація:
Abstract The North Purulia Shear Zone that dissects the granulite basement of the Chotanagpur Granite Gneissic Complex of the East Indian Shield exposes a deformed and metamorphosed nepheline syenite. The studied ‘foid-monzosyenite’ shows high abundances of large ion lithophile elements and high field strength elements with low abundances of compatible elements. Trace-element signatures show negative U, Th, Zr, Ti and Pb and positive Sr, Ba and Eu anomalies with respect to the primitive mantle. The chondrite-normalized diagram shows strongly fractionated rare earth element patterns ((La/Lu)N ∼23–87). Geochemical fingerprints suggest that the basanitic protolith was formed by low-degree partial melting of garnet peridotite in the sub-continental lithospheric mantle. The enriched large ion lithophile, high field strength element and light rare earth element concentrations (relative to primitive mantle) can be explained by a mixed mantle source with components from a previously deformed alkaline rock/carbonatite. Geochemical data do not support any significant crustal contamination and suggest variable fractionation of clinopyroxene, ilmenite, titanite and apatite from the parental melt. Petrological data are consistent with the view that the nepheline syenite magma was emplaced in a rift setting with a minimum temperature of 800–900°C, low fO2 conditions (below the fayalite–magnetite–quartz buffer) at a mid-crustal depth between 950 and 900 Ma. The continental rift zone, however, did not lead to the formation of an open ocean basin. Subsequently, the studied rock and its basement was deformed and metamorphosed in a continent–continent collisional setting at ∼900 Ma. Combining information from the other Indian occurrences with this study, it is demonstrated that the deformed alkaline rocks and carbonatite are potentially valuable for tracing the birth and demise of the palaeo-supercontinents.
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Sałacińska, Anna, Ianko Gerdjikov, Ashley Gumsley, Krzysztof Szopa, David Chew, Aleksandra Gawęda, and Izabela Kocjan. "Two stages of Late Carboniferous to Triassic magmatism in the Strandja Zone of Bulgaria and Turkey." Geological Magazine, July 21, 2021, 1–14. http://dx.doi.org/10.1017/s0016756821000650.
Повний текст джерелаАнотація:
Abstract Although Variscan terranes have been documented from the Balkans to the Caucasus, the southeastern portion of the Variscan Belt is not well understood. The Strandja Zone along the border between Bulgaria and Turkey encompasses one such terrane linking the Balkanides and the Pontides. However, the evolution of this terrane, and the Late Carboniferous to Triassic granitoids within it, is poorly resolved. Here we present laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS) U–Pb zircon ages, coupled with petrography and geochemistry from the Izvorovo Pluton within the Sakar Unit (Strandja Zone). This pluton is composed of variably metamorphosed and deformed granites which yield crystallization ages of c. 251–256 Ma. These ages are older than the previously assumed age of the Izvorovo Pluton based on a postulated genetic relationship between the Izvorovo Pluton and Late Jurassic to Early Cretaceous metamorphism. A better understanding of units across the Strandja Zone can now be achieved, revealing two age groups of plutons within it. An extensive magmatic episode occurred c. 312–295 Ma, and a longer-lived episode between c. 275 and 230 Ma. Intrusions associated with both magmatic events were emplaced into pre-Late Carboniferous basement, and were overprinted by Early Alpine metamorphism and deformation. These two stages of magmatism can likely be attributed to changes in tectonic setting in the Strandja Zone. Such a change in tectonic setting is likely related to the collision between Gondwana-derived terranes and Laurussia, followed by either subduction of the Palaeo-Tethys Ocean beneath Laurussia or rifting in the southern margin of Laurussia, with granitoids forming in different tectonic environments.