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1
Tripathi, C. "Volcanism in Gondwanas." Journal of Palaeosciences 36 (December 31, 1987): 285–89. http://dx.doi.org/10.54991/jop.1987.1587.
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In India the Lower Permian event is marked by a major volcanic episode in the Himalayan belt and rift faulting in the Peninsula which gave rise to various Gondwana basins. The Lower Cretaceous major volcanic episode represented by the Rajmahal Trap represents the termination of Gondwana sedimentation. Lower Permian volcanism is represented by the Panjal Volcanics in Kashmir Basin and its equivalent, the Volcanics in Spiti-Zanskar Basin and Rotung Volcanics (Abor Volcanics) in Arunachal Pradesh. In Karakarom Basin of Ladakh, volcanism is associated with Changtash and Aqtash formations of Permian age.
The Agglomeratic Slates in Kashmir are supposed to have originated as explosive volcanism in the form of pyroclastic which was followed later by flows of the Panjal Volcanics represented by subaqueous and subaerial tholeiitic basalt with occasional basaltic, andesitic and rhyolitic volcanics. The Agglomeratic slates are divided into two divisions, the Lower Diamicites and the Upper Pyroclastic. At the base of the Pyroclastic division and at the top of the Diamictite division, we get Eurydesma-Deltopecten Fauna of Lower Permian age. It is thus established that volcanism in Kashmir, Spiti-Zanskar and Ladakh is restricted to Lower Permian only. The sills and dykes associated with the underlying sequence in Syringothyris Limestone and Fenestella Shale in Kashmir, in Lipak and Po Formations in Spiti are related to this volcanism.
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McDOUGALL, IAN. "Age of volcanism and its migration in the Samoa Islands." Geological Magazine 147, no. 5 (February 10, 2010): 705–17. http://dx.doi.org/10.1017/s0016756810000038.
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AbstractPotassium–argon (K–Ar) ages on whole rock samples have been measured on lavas from the subaerial Samoa Islands, which form a broadly linear volcanic chain that extends from the ESE to the WNW for about 360 km. The Manu'a Islands near the southeast limit of the chain exhibit youthful ages, with most <0.4 Ma, in keeping with the geological observations. Tutuila consists of several volcanoes, and previous work yielded a mean K–Ar age of 1.26 ± 0.15 Ma for the shield-building volcanism. Upolu, to the WNW of Tutuila, gives a mean age of 2.15 ± 0.35 Ma for the shield-building phase, represented by the Fagaloa Volcanics, with much of the island covered by significantly younger volcanic rocks. Savai'i, further to the WNW, is dominated by youthful volcanism, extending into historic times. In a restricted area, adjacent to the NE coast of Savai'i, previously thought to have volcanic rocks correlating with the Fagaloa Volcanics of Upolu, the ages are much younger than those on Upolu, lying between 0.32 and 0.42 Ma. Considering only the subaerial volcanism from Ta'u to Upolu, but also including Vailulu'u, the volcanism has migrated in a systematic ESE direction at 130 ± 8 mm a−1 over 300 km in the last 2.2 Ma. This rate is nearly twice that obtained from GPS measurements of Pacific Plate motion of 72 mm a−1 at N64°W in this area. However, if the much older age of shield-building volcanism from the submarine foundations of Savai'i is included, the regression yields a volcanic migration rate of 72 ± 14 mm a−1, in keeping with the measured GPS rate and consistent with a hotspot origin for the island chain. This suggests that the volcanic migration rates determined from the age of subaerial volcanism can be considerably overestimated, and this is now evident in other Pacific Ocean island chains. Clearly, the ages of the main shield-building volcanism from subaerial volcanism are minima, and if the older submarine lavas can be measured, these may yield a migration rate more in keeping with current plate motions.
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Smellie, John L. "Chapter 3.2a Bransfield Strait and James Ross Island: volcanology." Geological Society, London, Memoirs 55, no. 1 (2021): 227–84. http://dx.doi.org/10.1144/m55-2018-58.
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AbstractFollowing more than 25 years of exploration and research since the last regional appraisal, the number of known subaerially exposed volcanoes in the northern Antarctic Peninsula region has more than trebled, from less than 15 to more than 50, and that total must be increased at least three-fold if seamounts in Bransfield Strait are included. Several volcanoes remain unvisited and there are relatively few detailed studies. The region includes Deception Island, the most prolific active volcano in Antarctica, and Mount Haddington, the largest volcano in Antarctica. The tectonic environment of the volcanism is more variable than elsewhere in Antarctica. Most of the volcanism is related to subduction. It includes very young ensialic marginal basin volcanism (Bransfield Strait), back-arc alkaline volcanism (James Ross Island Volcanic Group) and slab-window-related volcanism (seamount offshore of Anvers Island), as well as volcanism of uncertain origin (Anvers and Brabant islands; small volcanic centres on Livingston and Greenwich islands). Only ‘normal’ arc volcanism is not clearly represented, possibly because active subduction virtually ceased atc.4 Ma. The eruptive environment for the volcanism varied between subglacial, marine and subaerial but a subglacial setting is prominent, particularly in the James Ross Island Volcanic Group.
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SIMKIN, T. "Monitoring Volcanism: Volcanic Hazards." Science 245, no. 4913 (July 7, 1989): 83–84. http://dx.doi.org/10.1126/science.245.4913.83.
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Ganelin, A. V., E. V. Vatrushkina, and M. V. Luchitskaya. "Geochemistry and geochronology of cretaceous volcanism of Chauna region, Central Chukotka." Геохимия 64, no. 1 (January 15, 2019): 20–42. http://dx.doi.org/10.31857/s0016-752564120-42.
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New geochronological and geochemical data on the age and composition of Cretaceous volcanism of Palyavaam River basin (Central Chukotka, Chauna region) are presented. First complex is composed of rhyolites, ignimbrites and felsic tuffs of Chauna Group of Okhotsk-Chukotka volcanic belt (OCVB). Second complex is represented by volcanic rocks of latite-shoshonite series of Early Cretaceous age, distinguished as Etchikun’ Formation. Its origin is still debatable. Some researchers refer deposits of Etchikun’ Formation to magmatic stage before OCVB activity. Other authors include in Chauna Group composition. Obtained data indicate heterogeneity of Etchikun’ Fomation volcanics and allow to divide them in two groups. Andesites of the first group (Etchikun’ Formation sensu stricto) have Early Cretaceous age and belong to magmatic stage before OCVB activity. Andesites of the second group correlate in age and composition with OCVB volcanic rocks. They occur at the base of Chauna Group and indicate homodromous character of volcanism evolution in the Central-Chukotka of Okhotsk-Chukotka volcanic belt.
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Smellie, John L. "Chapter 1.2 Antarctic volcanism: volcanology and palaeoenvironmental overview." Geological Society, London, Memoirs 55, no. 1 (2021): 19–42. http://dx.doi.org/10.1144/m55-2020-1.
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AbstractSince Jurassic time (c.200 Ma), Antarctica has had a greater diversity of volcanism than other southern continents. It includes: (1) voluminous mafic and felsic volcanism associated with the break-up of Gondwana; (2) a long-lived continental margin volcanic arc, including back-arc alkaline volcanism linked to slab rollback; (3) small-volume mafic alkaline volcanism associated with slab-window formation; and (4) one of Earth's major continental rift zones, the West Antarctic Rift System (WARS), with its numerous large alkaline central volcanoes. Several of Antarctica's volcanoes are still active. This chapter is a review of the major volcanic episodes and their principal characteristics, in their tectonic, volcanological and palaeoenvironmental contexts. Jurassic Gondwana break-up was associated with large-scale volcanism that caused global environmental changes and associated mass extinctions. The volcanic arc was a major extensional arc characterized by alternating volcanic flare-ups and lulls. The Neogene rift-related alkaline volcanism is dominated by effusive glaciovolcanic eruptions, overwhelmingly as both pāhoehoe- and ‘a‘ā-sourced lava-fed deltas. The rift is conspicuously poor in pyroclastic rocks due to the advection and removal of tephra erupted during glacial intervals. Volcanological investigations of the Neogene volcanism have also significantly increased our knowledge of the critical parameters and development of the Antarctic Ice Sheet.
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Kitsopoulos, K. "MAGMA GENERATION AND MIXING IN THE EARLIEST VOLCANIC CENTRE OF SANTORINI (AKROTIRI PENINSULA). MINERAL CHEMISTRY EVIDENCE FROM THE AKROTIRI PYROCLASTICS." Bulletin of the Geological Society of Greece 43, no. 5 (July 31, 2017): 2625. http://dx.doi.org/10.12681/bgsg.11669.
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Santorini is a dominant expression of magma generation and subsequent volcanism in the Meditereanean area, where a calk-alkaline, high-alumina, basalt-andesite-dacite type of volcanism was expressed from eight centres. The volcanics of the Akrotiri peninsula are considered to be the products of the earliest (Pliocene Pleistocene) volcanic centre. The present study has investigated the mineral chemistry of some major pyrogenic phenocrysts, such as plagioclase and Fe-Ti oxides, of the Akrotiri pyroclatics unit, which have undergone a notable zeolitization procedure. The results are compatible with magma mixing mechanism of a primitive mantle derived, saturated, of mafic composition component with silicic magma in shallow crustal depths.
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Ludden, John, Claude Hubert, and Clement Gariépy. "The tectonic evolution of the Abitibi greenstone belt of Canada." Geological Magazine 123, no. 2 (March 1986): 153–66. http://dx.doi.org/10.1017/s0016756800029800.
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AbstractBased on structural, geochemical, sedimentological and geochronological studies, we have formulated a model for the evolution of the late Archaean Abitibi greenstone belt of the Superior Province of Canada. The southern volcanic zone (SVZ) of the belt is dominated by komatiitic to tholeiitic volcanic plateaux and large, bimodal, mafic-felsic volcanic centres. These volcanic rocks were erupted between approximately 2710 Ma and 2700 Ma in a series of rift basins formed as a result of wrench-fault tectonics.The SVZ superimposes an older volcanic terrane which is characterized in the northern volcanic zone (NVZ) of the Abitibi belt and is approximately 2720 Ma or older. The NVZ comprises basaltic to andesitic and dacitic subaqueous massive volcanics which are cored by comagmatic sill complexes and layered mafic-anorthositic plutonic complexes. These volcanics are overlain by felsic pyroclastic rocks that were comagmatic with the emplacement of tonalitic plutons at 2717 ±2 Ma.The tectonic model envisages the SVZ to have formed in a series of rift basins which dissected an earlier formed volcanic arc (the NVZ). Analogous rift environments have been postulated for the Hokuroko basin of Japan, the Taupo volcanic zone of New Zealand and the Sumatra and Nicaragua arcs. The difference between rift related ‘submergent’ volcanism in the SVZ and ‘emergent’ volcanism in the NVZ resulted in the contrasting metallogenic styles, the former being characterized by syngenetic massive sulphide deposits, whilst the latter was dominated by epigenetic ‘porphyry-type’ Cu(Au) deposits.
9
CITRONI, SERGIO B., MIGUEL A. S. BASEI, OSWALDO SIGA JR., and JOSÉ M. DOS REIS NETO. "Volcanism and stratigraphy of the Neoproterozoic Campo Alegre Basin, SC, Brazil." Anais da Academia Brasileira de Ciências 73, no. 4 (December 2001): 581–97. http://dx.doi.org/10.1590/s0001-37652001000400012.
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The depositional succession of the Campo Alegre Basin (Santa Catarina - southern Brazil) was investigated having the evolution of the volcanic activity as background. The different stratigraphic units are interpreted as belonging to different volcanic stages: Bateias Formation, conglomerates and sandstones, related with a pre-volcanic stage; Campo Alegre Group, at the main volcanic stage, with each different formation corresponding to different episodes of volcanism - Rio Negrinho Formation, corresponding to the basic volcanism, Avenca Grande Formation to ignimbritic event, Serra de São Miguel Formation to the acid volcanism and Fazenda Uirapuru Formation, related to an explosive event; Rio Turvo and Arroio Água Fria formations correspond respectively to inner and extra-caldera deposits.
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Griffiths, Chris J., and Richard D. J. Oglethorpe. "The stratigraphy and geochronology of Adelaide Island." Antarctic Science 10, no. 4 (December 1998): 462–75. http://dx.doi.org/10.1017/s095410209800056x.
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The Mesozoic-Cenozoic volcanic arc of the Antarctic Peninsula is represented on Adelaide Island by a sedimentary and volcanic succession intruded by plutons. 40Ar-39 Ar step-heating age spectra have been obtained from volcanic rocks and hornblende separates from sedimentary clasts of plutonic origin. These spectra show evidence for some argon loss, but, in general, have plateau ages which are consistent with the mapped stratigraphy and with other geochronological controls, suggesting that they approximate to original ages. As a result the following events in the evolution of Adelaide Island can be recognized:1) mostly marine Mesozoic sedimentation, 2) Early Cretaceous (c. 141 Ma) plutonism (recorded in clasts from conglomerates), 3) Cretaceous volcanism, 4) Late Cretaceous (possibly Tertiary) sedimentation, 5) Early Tertiary volcanism, which was acidic in eastern outcrops and intermediate elsewhere, and 6) Eocene intermediate volcanism and deposition of arc-derived conglomerates. Volcanism was possibly coeval with known Palaeocene-Eocene plutonic activity on Adelaide Island (part of the Antarctic Peninsula Batholith) and with volcanism of similar age in northern Alexander Island and the South Shetland Islands. The volcanism on Adelaide Island and the South Shetland Islands, at least, was associated with a westward migration of the Antarctic Peninsula arc.
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Li, Xiaoyi, Wenliang Du, Hanwen Cui, and Xiaolin Tian. "The crater with gravity anomaly in the center may be the ancient volcanic crater and geothermal under it." Thermal Science 23, no. 5 Part A (2019): 2765–74. http://dx.doi.org/10.2298/tsci181210190l.
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Lunar volcanism play an important role on studying the thermal and compositional evolution of the Moon. However, the studies on the relationships among composition, location and age of Lunar volcanos are still limit. The high-quality and multi-source remote sensing data offer the opportunity to obtain significant features of the Lunar volcanism and the evolution of the Moon. Specifically, the high-quality gravitational features of volcanic landforms of the Moon are observed by the Gravity Recovery and Interior Laboratory. Besides, the lunar reconnaissance orbiter camera provides detail morphologic features of Lunar volcanos based on high-resolution optical images. This paper aims to find the characteristic of lunar volcanos by observing the gravitational and morphologic features in the center of craters. The final results show that most of the craters with central peaks have gravity anomalies except the Mendeleev crater (5.7?N and 140.9?E) whose central area contains significant gravity anomalies but no central peaks. The area of gravity anomaly may indicate heat source under the ground.
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Fadda, S., M. Fiori, S. Pretti, and P. Valera. "MANGANESE MINERALISATIONS AT THE BASE OF MIOCENE SEDIMENTS IN NORTHERN SARDINIA (ITALY)." Bulletin of the Geological Society of Greece 43, no. 5 (July 31, 2017): 2588. http://dx.doi.org/10.12681/bgsg.11666.
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During the eastward drift of the Palaeozoic-Mesozoic block formed by Sardinia and Corsica in the Oligocene-Miocene, calc-alkaline volcanism developed mostly in the western part of the island. Most Tertiary metallogenic phoenomena are related to hydrothermal activity associated with this volcanism. Following volcanic and related hydrothermal activity, sediments were deposited during the Oligocene-Miocene as a consequence of a marine transgression. The basal part of this series is clastic and includes elements derived from erosion of unaltered volcanics as well as hydrothermally altered rocks and hydrothermal vein quartz. Inside the Tertiary volcanics manganese ore-minerals occur as nodules, veinlets, and stockworks and mainly include Mn and Fe oxides; quartz in different forms is the most common gangue mineral. The mineralisations at the contact between volcanics and Miocene sediments are the most homogeneous, the ore-minerals occur in the cement, but also as fairly continuous thin beds, nodules and veinlets containing pyrolusite, frequent ramsdellite, less frequent manganite, psilomelane, cryptomelane-manjiroite, rare ranciéite, and todorokite. The nature of the ore-bearing beds indicate a near-shore clastic environment along the ancient coastal lines of the Miocene sea. Genetic considerations point to a supergenic transport and redeposition after erosion of primary dispersion and residual concentrations of Mn in the volcanics.
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Barberi, F., M. Coltelli, G. Ferrara, F. Innocenti, J. M. Navarro, and R. Santacroce. "Plio-Quaternary volcanism in Ecuador." Geological Magazine 125, no. 1 (January 1988): 1–14. http://dx.doi.org/10.1017/s0016756800009328.
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AbstractExtensive sampling, major element chemistry on over 300 samples and K-Ar radiometric dating have been carried out on the Ecuadorian Upper Tertiary–Quaternary volcanoes. The results show important space–time variations of the volcanic activity, between Late Miocene time and the present. In Late Miocene time a continuous volcanic belt, located approximately along the present volcanic front (VF), affected the whole country from the Cuenca basin to the south, up to Colombia to the north. Major changes occurred at about 5 Ma: volcanic activity stopped south of the Guayaquil fault belt and never resumed; to the north the active volcanic axis shifted eastward to the Cordillera Real (CR) area with a simultaneous relative decrease in intensity. Since Early Quaternary time the volcanic belt widened westward to the Western Cordillera where the volcanism resumed at about 1.5–1.0 Ma, giving rise to the very wide active volcanic zone of Ecuador.The Plio-Quaternary products show significant longitudinal and latitudinal chemical and mineralogical changes. Volcanics of the VF and Interandean Depression contain amphibole and define a calc-alkaline trend with a K2O content lower than that of the CR products, which are characterized by a mostly anhydrous phenocryst assemblage. In both areas andesites dominate, but extreme compositions (basaltic andesites and rhyolites) are more diffuse in the CR than the VF. No significant transverse zoning has been detected in the northern region (north of the Chota-Mira transverse tectonic line). The observed temporal and spatial variations are interpreted as a result of the subduction of the Carnegie Ridge anomalous oceanic crust, underthrusting of which began approximately 6 Ma ago.
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Megerle, Heidi Elisabeth. "Geoheritage and Geotourism in Regions with Extinct Volcanism in Germany; Case Study Southwest Germany with UNESCO Global Geopark Swabian Alb." Geosciences 10, no. 11 (November 8, 2020): 445. http://dx.doi.org/10.3390/geosciences10110445.
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Geotourism has become more popular in recent decades. Volcanism is an essential part of geoheritage and attracts a high number of visitors. In contrast to active volcanism, Tertiary volcanism is often not identified as such by a lay audience and is understandably perceived as less spectacular. The challenge is therefore to protect the volcanic heritage, to communicate its values, and to enhance it with the help of adequate geotourism offers. Germany does not have active volcanism, but a very high quality volcanic geological heritage, especially from the Tertiary period. Fortunately, this heritage is being increasingly valued and presented in an attractive way for a lay audience. The two Geoparks in the Eifel (Rhineland-Palatinate) are pioneers in this field. The UNESCO Global Geopark Swabian Alb actually offers a well camouflaged potential. The Swabian volcano, with an area of 1600 km2, is one of the most important tuff vent areas on earth, but hardly known outside of expert groups. A comprehensive strategy for the geotouristic valorization of the Tertiary volcanic phenomena does not yet exist in the Geopark Swabian Alb.
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Truong, N., and J. I. Lunine. "Volcanically extruded phosphides as an abiotic source of Venusian phosphine." Proceedings of the National Academy of Sciences 118, no. 29 (July 12, 2021): e2021689118. http://dx.doi.org/10.1073/pnas.2021689118.
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We hypothesize that trace amounts of phosphides formed in the mantle are a plausible abiotic source of the Venusian phosphine observed by Greaves et al. [Nat. Astron., https://doi.org/10.1038/s41550-020-1174-4 (2020)]. In this hypothesis, small amounts of phosphides (P3− bound in metals such as iron), sourced from a deep mantle, are brought to the surface by volcanism. They are then ejected into the atmosphere in the form of volcanic dust by explosive volcanic eruptions, which were invoked by others to explain the episodic changes of sulfur dioxide seen in the atmosphere [Esposito, Science 223, 1072–1074 (1984)]. There they react with sulfuric acid in the aerosol layer to form phosphine (2 P3− + 3H2SO4 = 2PH3 + 3SO42-). We take issue with the conclusion of Bains et al. [arXiv:2009.06499 (2020)] that the volcanic rates for such a mechanism would have to be implausibly high. We consider a mantle with the redox state similar to the Earth, magma originating deep in the mantle—a likely scenario for the origin of plume volcanism on Venus—and episodically high but plausible rates of volcanism on a Venus bereft of plate tectonics. We conclude that volcanism could supply an adequate amount of phosphide to produce phosphine. Our conclusion is supported by remote sensing observations of the Venusian atmosphere and surface that have been interpreted as indicative of currently active volcanism.
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KEPPIE, J. D., J. DOSTAL, J. B. MURPHY, and B. L. COUSENS. "Palaeozoic within-plate volcanic rocks in Nova Scotia (Canada) reinterpreted: isotopic constraints on magmatic source and palaeocontinental reconstructions." Geological Magazine 134, no. 4 (July 1997): 425–47. http://dx.doi.org/10.1017/s001675689700719x.
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Palaeozoic volcanism in the Avalon Terrane of northern Nova Scotia occurred during three time intervals: Cambrian–early Ordovician, late Ordovician–early Silurian and middle–late Devonian. In the Meguma Terrane of southern Nova Scotia, Palaeozoic volcanism is limited to the middle Ordovician. Geochemical data show that most of these volcanic rocks are bimodal, within-plate suites. Initial εNd signatures range from +5.4 to −1.9 in the rhyolites and +6.8 to +2.7 in the basalts, a difference attributable to the absence or presence, respectively, of a significant crustal component. The data and regional tectonic settings of the Avalon and Meguma terranes suggest that the volcanism was generated in three different within-plate settings: (1) Cambrian–early Ordovician volcanism related to thermal decay of late Proterozoic arc magmatism during transtensional deformation; (2) middle Ordovician–early Silurian volcanism during sinistral telescoping between Laurentia and Gondwana where extensional bends in the Appalachians produced rifting; and (3) Devonian volcanism resulting from lithospheric delamination during dextral transpression and telescoping. In each setting, active faults served as conduits for the magmas. Nd isotopic data indicate that the source of the Palaeozoic felsic volcanic rocks is isotopically indistinguishable beneath southern and northern Nova Scotia and did not substantially change with time. This crustal source appears to have separated from the mantle during the Proterozoic, a conclusion consistent with the hypothesis that the Palaeozoic rocks in Nova Scotia were deposited upon a late Proterozoic oceanic–cratonic volcanic arc terrane. The Nd data, when combined with published faunal, palaeomagnetic and U–Pb isotopic data, suggest that the Avalon Terrane was peripheral to Gondwana off northwestern South America during Neoproterozoic and early Palaeozoic times.
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Helgason, Jóhann, and Robert A. Duncan. "Stratigraphy, 40Ar–39Ar dating and erosional history of Svínafell, SE-Iceland." Jökull 63, no. 1 (December 15, 2013): 33–54. http://dx.doi.org/10.33799/jokull2013.63.033.
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The interplay of volcanism and erosion in the Svínafell massif, on the western slope of the Öræfajökull volcanic center, SE-Iceland, is traced with geological mapping, magnetostratigraphy and $^{40}$Ar–$^{39}$Ar age determinations. The volcanic strata are mainly of Quaternary age, i.e., geomagnetic chrons of lower Matuyama to upper Brunhes. The 1832 m thick sequence in Svínafell is composed of 37 discrete lithologic formations, assigned to seven volcano-stratigraphic groups beginning with the onset of volcanism in the Öræfajökull stratovolcano during lower Brunhes magnetic chron (C1n < 781 ka). A regional basin formed shortly before the initiation of volcanism, generating a depocenter for the plant-fossil bearing Svínafell sediments between 0.70 and 1.78 Ma. The Svínafell volcanic strata accumulated during a minimum of eight glacial and inter-glacial stages. We document the Svínafell erosion history and landscape evolution, including 12 erosion surfaces. Erosion has led to extended stratigraphic hiatuses and removal of thick volcanic sequences.
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Sánchez, John J., and William A. Posada. "Old and modern volcanic depictions as evidence of communities-volcanoes mutualism in Colombia." Andean Geology 51, no. 1 (January 31, 2024): 86. http://dx.doi.org/10.5027/andgeov51n1-3667.
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Studying the different ways in which the concept of volcanism is represented is crucial in the understanding of communities’ perception of the volcanic phenomena. In this contribution, 129 modern (2021-2023) depictions of volcanoes in Colombia between latitudes 0.82 and 5.96° N are described and classified into different contexts of use. Prehispanic depictions of volcanism are investigated in rock art sites (3 pictographs and 33 petroglyphs), and 15 distinct mythical narratives compiled and confirmed through interviews in the State of Nariño. We suggest that many of the rock art sites contain motifs that are reminiscent of the idea of volcanism, and that many of the folk tales include allusions to the volcanic concept. By collating the information contained in modern and older depictions, a link is established with the reality of the volcanic phenomena that shows how mutualism takes root between communities and volcanoes. The beneficial aspects derived from this relationship influence the perception of volcanic hazards in the region.
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AWDANKIEWICZ, MAREK, RYSZARD KRYZA, and NORBERT SZCZEPARA. "Timing of post-collisional volcanism in the eastern part of the Variscan Belt: constraints from SHRIMP zircon dating of Permian rhyolites in the North-Sudetic Basin (SW Poland)." Geological Magazine 151, no. 4 (September 12, 2013): 611–28. http://dx.doi.org/10.1017/s0016756813000678.
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AbstractThe final stages of the Variscan orogeny in Central Europe were associated with voluminous granitic plutonism and widespread volcanism. Four samples representative of the main rhyolitic volcanic units from the Stephanian–Permian continental succession of the North-Sudetic Basin, in the eastern part of the Variscan Belt, were dated using the SIMS (SHRIMP) zircon method. Three samples show overlapping206Pb–238U mean ages of 294 ± 3, 293 ± 2 and 292 ± 2 Ma, and constrain the age of the rhyolitic volcanism in the North-Sudetic Basin at 294–292 Ma. This age corresponds to the Early Permian – Sakmarian Stage and is consistent with the stratigraphic position of the lava units. The fourth sample dated at 288 ± 4 Ma reflects a minor, younger stage of (sub)volcanic activity in the Artinskian. The silicic activity was shortly followed by mafic volcanism. The rhyolite samples contained very few inherited zircons, possibly owing to limited contribution of crustal sources to the silicic magma, or owing to processes involved in anatectic melting and magma differentiation (e.g. resorption of old zircon by Zr-undersaturated melts). The SHRIMP results and the stratigraphic evidence suggest that the bimodal volcanism terminated the early, short-lived (10–15 Ma) and vigorous stage of basin evolution. The Permian volcanism in the North-Sudetic Basin may be correlated with relatively late phases of the regional climax of Late Palaeozoic volcanism in Central Europe, constrained by 41 published SHRIMP zircon age determinations at 299–291 Ma. The Permian volcanism and coeval plutonism in the NE part of the Bohemian Massif can be linked to late Variscan, post-collisional extension.
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Zakharikhina, L. V., and Yu S. Litvinenko. "Volcanism and geochemistry of soil and vegetation cover of Kamchatka. Communication 2. Specificity of forming the elemental composition of volcanic soil in cold and humid conditions." Вулканология и сейсмология, no. 3 (May 14, 2019): 25–33. http://dx.doi.org/10.31857/s0203-03062019325-33.
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Volcanic soils of Kamchatka have the low contents of most the chemical elements in relation to their overall prevalence in the soils of continents and volcanic soils of Europe. Relatively increased gross contents of elements typical for volcanic rocks of medium and basic composition: Na, Ca, Mg, Cd, Mn, Co, Cu, and steadily low contents of elements characteristic of acid volcanics: La, Ce, Pr, Nd, Nb, Hf, Tl, Rb and Th, is most characteristic of the soils of different areas of the peninsula. The existing in the past and currently observed different conditions of volcanism in the previously allocated soil areas of Kamchatka determine the diversity of the chemical composition of the soils in these territories.
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Zakharikhina, L. V., and Yu S. Litvinenko. "Volcanism and geochemistry of soil and vegetation cover of Kamchatka. Communication 2. Specificity of forming the elemental composition of volcanic soil in cold and humid conditions." Вулканология и сейсмология, no. 3 (May 14, 2019): 25–33. http://dx.doi.org/10.31857/s0205-96142019325-33.
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Volcanic soils of Kamchatka have the low contents of most the chemical elements in relation to their overall prevalence in the soils of continents and volcanic soils of Europe. Relatively increased gross contents of elements typical for volcanic rocks of medium and basic composition: Na, Ca, Mg, Cd, Mn, Co, Cu, and steadily low contents of elements characteristic of acid volcanics: La, Ce, Pr, Nd, Nb, Hf, Tl, Rb and Th, is most characteristic of the soils of different areas of the peninsula. The existing in the past and currently observed different conditions of volcanism in the previously allocated soil areas of Kamchatka determine the diversity of the chemical composition of the soils in these territories.
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Geyer, A. "Chapter 1.4 Antarctic volcanism: active volcanism overview." Geological Society, London, Memoirs 55, no. 1 (2021): 55–72. http://dx.doi.org/10.1144/m55-2020-12.
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AbstractIn the last two centuries, demographic expansion and extensive urbanization of volcanic areas have increased the exposure of our society to volcanic hazards. Antarctica is no exception. During the last decades, the permanent settlement and seasonal presence of scientists, technicians, tourists and logistical personnel close to active volcanoes in the south polar region have increased notably. This has led to an escalation in the number of people and the amount of infrastructure exposed to potential eruptions. This requires advancement of our knowledge of the volcanic and magmatic history of Antarctic active volcanoes, significant improvement of the monitoring networks, and development of long-term hazard assessments and vulnerability analyses to carry out the required mitigation actions, and to elaborate on the most appropriate response plans to reduce loss of life and infrastructure during a future volcanic crisis. This chapter provides a brief summary of the active volcanic systems in Antarctica, highlighting their main volcanological features, which monitoring systems are deployed (if any), and recent (i.e. Holocene and/or historical) eruptive activity or unrest episodes. To conclude, some notes about the volcanic hazard assessments carried out so far on south polar volcanoes are also included, along with recommendations for specific actions and ongoing research on active Antarctic volcanism.
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Šimon, Ladislav, Viera Kollárová, and Monika Kováčiková. "Neogene volcanics of the Burda mountain range nearby Štúrovo, Slovakia." Mineralia Slovaca 55, no. 2 (December 2023): 117–32. http://dx.doi.org/10.56623/ms.2023.55.2.2.
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The Neogene volcanic products of the Burda mountain range nearby Štúrovo belong to Burda Formation. At the base of the Burda Formation a succession of epiclastic volcanic rocks and pyroclastic rocks of andesites has developed. In the central part of the formation, the volcanic products associated with the activity of submarine volcanism of the Badenian age developed. Submarine extrusive volcanic domes of andesites are typical. In the upper part of the Burda Formation, pyroclastic and epiclastic facies of andesites were formed. Deposits of pyroclastic flows and redeposited pyroclastics are characterized by the presence of relics of petrified tree trunks, indicating transport from emergent forest-covered slopes from the higher levels of the volcanic edifice of the Börzsöny Mountains in todayʼs Hungary. This part of the Burda volcanics represents a transitional volcanic zone with the Börzsöny stratovolcano.
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Stelten, Mark E., Drew T. Downs, Duane E. Champion, Hannah R. Dietterich, Andrew T. Calvert, Thomas W. Sisson, Gail A. Mahood, and Hani Zahran. "The timing and compositional evolution of volcanism within northern Harrat Rahat, Kingdom of Saudi Arabia." GSA Bulletin 132, no. 7-8 (November 4, 2019): 1381–403. http://dx.doi.org/10.1130/b35337.1.
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Abstract Harrat Rahat, one of several large, basalt-dominated volcanic fields in western Saudi Arabia, is a prime example of continental, intraplate volcanism. Excellent exposure makes this an outstanding site to investigate changing volcanic flux and composition through time. We present 93 40Ar/39Ar ages and six 36Cl surface-exposure ages for volcanic deposits throughout northern Harrat Rahat that, when integrated with a new geologic map, define 12 eruptive stages. Exposed volcanic deposits in the study area erupted <1.2 Ma, and 214 of 234 eruptions occurred <570 ka. Two eruptions occurred in the Holocene, including a historically described basalt eruption in 1256 C.E. and a trachyte eruption newly recognized as Holocene (4.2 ± 5.2 ka). An estimated ∼82 km3 (dense rock equivalent) of volcanic product have erupted since 1.2 Ma, though this is a lower limit due to concealment of deposits >570 ka. Over the past 570 k.y., the average eruption rate was 0.14 km3/k.y., but volcanism was episodic with periods alternating between low (0.04–0.06 km3/k.y.) and high (0.1–0.3 km3/k.y.) effusion rates. Before 180 ka, eruptions vented from the volcanic field’s dominant eastern vent axis and from a subsidiary, diffuse, western vent axis. After 180 ka, volcanism focused along the eastern vent axis, and the composition of volcanism varied systematically along its length from basalt dominated in the north to trachyte dominated in the south. We hypothesize that these compositional variations <180 ka reflect the growth of a mafic intrusive complex beneath the southern portion of the vent axis, which led to the development of evolved magmas.
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KAYIN, Sercan, and Turgay İŞSEVEN. "PALEOMAGNETISM OF QUATERNARY VOLCANISM OF THE MOUNT NEMRUT." Euroasia Journal of Mathematics, Engineering, Natural & Medical Sciences 9, no. 20 (March 25, 2022): 92–101. http://dx.doi.org/10.38065/euroasiaorg.935.
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As a result of the convergence between the Arabian plate and the Anatolian block, a continentcontinent collision occurred in the region along the Bitlis Zargos sutur zone. Following the collision, volcanic activity began in the Late Miocene and produced volcanic material throughout the region and reach to the Caucasus. Collision-related volcanism in eastern Anatolia covered almost two-thirds of the area and formed volcanic products up to 1 km thick. In order to determine the tectonic evolution of Mount Nemrut and its around, paleomagnetic core samples were collected from a total of 11 sites from Pleistocene - Holocene time interval aged volcanic rocks. Paleomagnetic laboratory studies were carried out in KANTEK Paleomagnetism Laboratory, and also rock magnetism studies were carried out in Istanbul University-Cerrahpaşa, Yılmaz İspir Paleomagnetism Laboratory. When the mean magnetization directions obtained from Mount Nemrut and its surrounding Holocene and Upper Pleistocene aged locations are examined, it is seen that there is an average of 7.3° clockwise rotation. It is also observed that the angle of inclination is 60°. These results obtained, considering the α95 circle (7.7°), it is observed that there is no tectonic rotation within the sensitivity limits of paleomagnetism in the region. At the same time, it can be interpreted that Mount Nemrut has not been exposed to a latitudinal movement since the Quaternary, but volcanics is still at the latitude where it was formed.
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Dawson, J. B. "Neogene–Recent rifting and volcanism in northern Tanzania: relevance for comparisons between the Gardar province and the East African Rift valley." Mineralogical Magazine 61, no. 407 (August 1997): 543–48. http://dx.doi.org/10.1180/minmag.1997.061.407.06.
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AbstractThe tectonic position of the intraplate, alkaline volcanic province of N. Tanzania in a broad rift-controlled area astride the boundary between the Tanzania Craton and the circum-cratonic Mozambique Fold Belt, strongly resembles that of the Gardar province of S. Greenland. Earlier-identified petrological analogies between Gardar magmatism and that in the Kenya sector of the East African Rift Valley can be extended to volcanism in N. Tanzania, and analogies specifically with the Gardar agpaitic suite are strengthened by the occurrence of eudialyte and aenigmatite in some Tanzanian peralkaline, silicic volcanics.
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Smellie, John L., and Adam P. Martin. "Chapter 5.2a Erebus Volcanic Province: volcanology." Geological Society, London, Memoirs 55, no. 1 (2021): 415–46. http://dx.doi.org/10.1144/m55-2018-62.
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AbstractThe Erebus Volcanic Province is the largest Neogene volcanic province in Antarctica, extendingc.450 km north–south and 170 km wide east–west. It is dominated by large central volcanoes, principally Mount Erebus, Mount Bird, Mount Terror, Mount Discovery and Mount Morning, which have sunk more than 2 km into underlying sedimentary strata. Small submarine volcanoes are also common, as islands and seamounts in the Ross Sea (Terror Rift), and there are many mafic scoria cones (Southern Local Suite) in the Royal Society Range foothills and Dry Valleys. The age of the volcanism ranges betweenc.19 Ma and present but most of the volcanism is <5 Ma. It includes active volcanism at Mount Erebus, with its permanent phonolite lava lake. The volcanism is basanite–phonolite/trachyte in composition and there are several alkaline petrological lineages. Many of the volcanoes are pristine, predominantly formed of subaerially erupted products. Conversely, two volcanoes have been deeply eroded. That at Minna Hook is mainly glaciovolcanic, with a record of the ambient mid–late Miocene eruptive environmental conditions. By contrast, Mason Spur is largely composed of pyroclastic density current deposits, which accumulated in a large mid-Miocene caldera that is now partly exhumed.
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TAKASHIMA, REISHI, HIROSHI NISHI, and TAKEYOSHI YOSHIDA. "Late Jurassic–Early Cretaceous intra-arc sedimentation and volcanism linked to plate motion change in northern Japan." Geological Magazine 143, no. 6 (September 4, 2006): 753–70. http://dx.doi.org/10.1017/s001675680600255x.
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The Sorachi Group, composed of Upper Jurassic ophiolite and Lower Cretaceous island-arc volcano-sedimentary cover, provides a record of Late Jurassic–Early Cretaceous sedimentation and volcanism in an island-arc setting off the eastern margin of the Asian continent. Stratigraphic changes in the nature and volume of the Sorachi Group volcanic and volcaniclastic rocks reveal four tectonic stages. These stages resulted from changes in the subduction direction of the Pacific oceanic plate. Stage I in the Late Jurassic was characterized by extensive submarine eruptions of tholeiitic basalt from the back-arc basin. Slab roll-back caused rifting and sea-floor spreading in the supra-subduction zone along the active Asian continental margin. Stage II corresponded to the Berriasian and featured localized trachyandesitic volcanism that formed volcanic islands with typical island-arc chemical compositions. At the beginning of this stage, movement of the Pacific oceanic plate shifted from northeastward to northwestward. During Stage III, in the Valanginian, submarine basaltic volcanism was followed by subsidence. The Pacific oceanic plate motion turned clockwise, and the plate boundary between the Asian continent and the Pacific oceanic plate changed from convergent to transform. During Stage IV in the Hauterivian–Barremian, in situ volcanism ceased in the Sorachi–Yezo basin, and the volcanic front migrated west of the Sorachi–Yezo basin.
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Vougioukalakis, Georges E., Christopher G. Satow, and Timothy H. Druitt. "Volcanism of the South Aegean Volcanic Arc." Elements 15, no. 3 (June 1, 2019): 159–64. http://dx.doi.org/10.2138/gselements.15.3.159.
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Volcanism along the South Aegean volcanic arc began about 4.7 Ma and has lasted until the present day, with eruptions at Methana, Milos, Santorini, Kolumbo and Nisyros volcanoes in historical times. These volcanoes can be grouped into five volcanic fields: three western fields of small, mostly monogenetic edifices, and two central/eastern fields with composite cones and calderas that have produced large explosive eruptions. Crustal tectonics exerts a strong control over the locations of edifices and vents at all five volcanic fields. Tephra and cryptotephra layers in deep-marine sediments preserve a continuous record of arc volcanism in the Aegean as far back as 200,000 years. Hazards from the volcanoes include high ash plumes, pyroclastic flows and tsunamis. Monitoring networks should be improved and expanded.
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Smellie, John L., Kurt S. Panter, and Jenna Reindel. "Chapter 5.3a Mount Early and Sheridan Bluff: volcanology." Geological Society, London, Memoirs 55, no. 1 (2021): 491–98. http://dx.doi.org/10.1144/m55-2018-61.
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AbstractTwo small monogenetic volcanoes are exposed at Mount Early and Sheridan Bluff, in the upper reaches of Scott Glacier. In addition, the presence of abundant fresh volcanic detritus in moraines at two other localities suggests further associated volcanism, now obscured by the modern Antarctic ice sheet. One of those occurrences has been attributed to a small subglacial volcano onlyc.200 km from South Pole, making it the southernmost volcano in the world. All of the volcanic outcrops in the Scott Glacier region are grouped in a newly defined Upper Scott Glacier Volcanic Field, which is part of the McMurdo Volcanic Group (Western Ross Supergroup). The volcanism is early Miocene in age (c.25–16 Ma), and the combination of tholeiitic and alkaline mafic compositions differs from the more voluminous alkaline volcanism in the West Antarctic Rift System. The Mount Early volcano was erupted subglacially, when the contemporary ice was considerably thicker than present. By contrast, lithologies associated with the southernmost volcano, currently covered by 1.5 km of modern ice, indicate that it was erupted when any associated ice was either much thinner or absent. The eruptive setting for Sheridan Bluff is uncertain and is still being investigated.
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Penatas, Dianti Lintang, Heather L. Moll, and Brigita Ajeng Andya Hariyana. "The Effect of Augmented Reality (AR) Based Multimedia ATLAS: Volcanic Series Volcanism Material on Learning Outcomes of Students of SMAN 2 Blitar." Future Space: Studies in Geo-Education 1, no. 3 (July 8, 2024): 325–35. http://dx.doi.org/10.69877/fssge.v1i3.32.
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The presence of Augmented Reality (AR) technology in education supports multimedia advances in learning, one of which is ATLAS: Volcanic Series. The use of multimedia in learning can facilitate the understanding of the material by students, so that good learning outcomes are achieved. The purpose of this research is to know the effect of Augmented Reality (AR) based multimedia ATLAS: Volcanic Series volcanism material on student learning outcomes of SMAN 2 Blitar. Quasi experimental is the type of this research and post-test only group design. As the method, the subjects in this study were students of class X (IPS 3 & IPS 4) SMAN 2 Blitar. Collecting data using quantitative methods through post-test results. The t-test technique (Independent Sample T-test) was carried out for data analysis in order to determine the effect of Augmented Reality (AR) based multimedia ATLAS: Volcanic Series on volcanism material on students' scores or learning outcomes in geography lessons. The results of this 2-week study show that multimedia based on Augmented Reality (AR) ATLAS: Volcanic Series volcanism material has a significant effect on learning outcomes at SMAN 2 Blitar.
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Quartini, Enrica, Donald D. Blankenship, and Duncan A. Young. "Chapter 7.5 Active subglacial volcanism in West Antarctica." Geological Society, London, Memoirs 55, no. 1 (2021): 785–803. http://dx.doi.org/10.1144/m55-2019-3.
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AbstractA combination of aerogeophysics, seismic observations and direct observation from ice cores, and subglacial sampling, has revealed at least 21 sites under the West Antarctic Ice Sheet consistent with active volcanism (where active is defined as volcanism that has interacted with the current manifestation of the West Antarctic Ice Sheet). Coverage of these datasets is heterogeneous, potentially biasing the apparent distribution of these features. Also, the products of volcanic activity under thinner ice characterized by relatively fast flow are more prone to erosion and removal by the ice sheet, and therefore potentially under-represented. Unsurprisingly, the sites of active subglacial volcanism that we have identified often overlap with areas of relatively thick ice and slow ice surface flow, both of which are critical conditions for the preservation of volcanic records. Overall, we find the majority of active subglacial volcanic sites in West Antarctica concentrate strongly along the crustal-thickness gradients bounding the central West Antarctic Rift System, complemented by intra-rift sites associated with the Amundsen Sea–Siple Coast lithospheric transition.
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Rosa, D. R. N., A. A. Finch, T. Andersen, and C. M. C. Inverno. "U-Pb geochronology of felsic volcanic rocks hosted in the Gafo Formation, South Portuguese Zone: the relationship with Iberian Pyrite Belt magmatism." Mineralogical Magazine 72, no. 5 (October 2008): 1103–18. http://dx.doi.org/10.1180/minmag.2008.072.5.1103.
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AbstractFelsic volcanic rocks exposed in the Frasnian Gafo Formation, in the Azinhalinho area of Portugal, display very similar geochemical signatures to volcanic rocks from the Iberian Pyrite Belt (IPB). located immediately to the south. The similarities include anomalously low high field-strength elements (HFSE) concentrations, possibly caused by low-temperature crustal melting, which translate into classification problems.A geochronological study, using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses of zircon grains from these rocks, has provided concordia ages of 356±1.5 Ma and 355±2.5 Ma for two samples of rhyodacite porphyry, and 356±1.4 Ma for a granular rhyodacite. These results show that volcanism at Azinhalinho was broadly contemporaneous with IPB volcanism, widely interpreted as being of Famennian to Visean age. Considering that the host rocks of the Azinhalinho volcanic rocks are Frasnian, and therefore deposited synchronously with the Upper Devonian Phyllite-Quartzite Group sedimentation in the IPB basin, the radiometric ages imply that the Azinhalinho felsic rocks are intrusive and likely represent conduits or feeders to the volcanism of the IPB.
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McDOUGALL, IAN, and FRANCIS H. BROWN. "Timing of volcanism and evolution of the northern Kenya Rift." Geological Magazine 146, no. 1 (September 19, 2008): 34–47. http://dx.doi.org/10.1017/s0016756808005347.
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AbstractThe northern Kenya Rift is bounded on the west by uplands of Turkana which comprise horst-like blocks that include metamorphic basement rocks, locally overlain unconformably by the Cretaceous Lubur Sandstone, in turn overlain by predominantly volcanic sequences in which relatively thin sedimentary packages occur. Amphibolite facies crystalline rocks of the basement yield Early Palaeozoic K–Ar cooling ages reflecting the Pan-African Orogeny. Volcanism in Turkana was initiated through voluminous eruptions of transitional tholeiitic basalts commencing about 36 Ma ago in the Late Eocene, with some evidence for concomitant rhyolitic volcanism. Volcanism became dominantly rhyolitic in the interval from about 27 to 23 Ma ago, but remained bimodal as basaltic lavas are also known from this period. From about 19 to 15 Ma or younger, basaltic volcanism again dominated, often alkaline in nature, with thin but significant sedimentary sequences interleaved that have yielded important vertebrate faunal assemblages. Parallels exist between the volcanic history recorded in Turkana and that found in the Nabwal Hills east of Lake Turkana. In the southern Turkana region, oil exploration by seismic methods and deep drill holes has shown the existence of northerly-trending half-graben with up to 7 km of fill, and that these developed from at least Oligocene and possibly Late Eocene times. This suggests that the widespread basaltic volcanism at about 36 Ma ago (Late Eocene) heralds an earlier initiation of the Kenya Rift in northern Kenya than most workers have previously suggested.
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Reuber, Kyle R., Jim Pindell, and Brian W. Horn. "Demerara Rise, offshore Suriname: Magma-rich segment of the Central Atlantic Ocean, and conjugate to the Bahamas hot spot." Interpretation 4, no. 2 (May 1, 2016): T141—T155. http://dx.doi.org/10.1190/int-2014-0246.1.
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The Demerara Rise is a prominent bathymetric feature that has been considered as a broad expression of shallow continental basement and used in conjunction with the Guinea Plateau as a pinning point for circum-Atlantic plate reconstructions. Previously, shallow-penetration, poorly imaged seismic data over the Demerara Rise were modeled with the lower sequences interpreted as continental crust at relatively shallow depths. However, new long-offset, deeply penetrating seismic data provide evidence that basement nearly or entirely comprises excessively thick volcanic strata (approximately 21 km). Seismic character and geometry, 2D gravity modeling, and volcanic margin analogs were used to identify unfaulted, convex-upward seaward dipping reflector (SDR) packages. These steeply dipping (approximately 20°) igneous successions are westwardly divergent, and occur as offlapping reflector sets in trains as long as 250 km. This rift-related volcanism now recognized at the Demerara Rise was probably conjugate to syn-rift volcanism in South Florida/Great Bahama Bank, and from this we have predicted a volcanic element for the Guinea Plateau. This volcanism could be linked to a Bahamas hot spot at the initial opening of the Central Atlantic. Six SDR packages have been interpreted below the Late Jurassic-Early Cretaceous carbonate section of the rise, indicating that the early volcanism produced a marine substrate upon which the subsequent carbonate bank section developed. We have inferred that this Early Cretaceous volcanic/carbonate margin continued into the Guinea Plateau of West Africa. The pre-Aptian section was inverted and peneplained with a strong angular unconformity prior to the Early Cretaceous opening of the Equatorial Atlantic seaway. The newly identified Central Atlantic volcanic margin of the Demerara Rise holds implications of a volcanic origin for its conjugate margins. We have confirmed a voluminous magma-rich opening of the southeastern Central Atlantic.
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ŞEN, PINAR ALICI, ABİDİN TEMEL, and ALAIN GOURGAUD. "Petrogenetic modelling of Quaternary post-collisional volcanism: a case study of central and eastern Anatolia." Geological Magazine 141, no. 1 (January 2004): 81–98. http://dx.doi.org/10.1017/s0016756803008550.
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Extensive continental collision-related volcanism occurred in Turkey during Neogene–Quaternary times. In central Anatolia, calc-alkaline to alkaline volcanism began in the Middle–Late Miocene. Here we report trace elemental and isotopic data from Quaternary age samples from central and eastern Anatolia. Most mafic lavas from central Anatolia are basalt and basaltic andesite, with lesser amounts of basaltic trachyandesite and andesite. All magma types exhibit enrichment in LILE (Sr, Rb, Ba and Pb) relative to HFSE (Nb, Ta). Trace element patterns are characteristic of continental margin volcanism with high Ba/Nb and Th/Nb ratios. 87Sr/86Sr and 143Nd/144Nd isotopic ratios of central Anatolian lavas range between 0.704105–0.705619 and 0.512604–0.512849, respectively. The Quaternary alkaline volcanism of eastern Anatolia has been closely linked to the collision between the Arabian and Eurasian plates. Karacadaǧ and Tendürek volcanic rocks are represented by alkali basalts and basaltic trachyandesites, respectively. As expected from their alkaline nature, they contain high abundances of LIL elements, but Tendürek lavas also show depletion in Nb and Ta, indicating the role of crustal contamination in the evolution of these magmas. 87Sr/86Sr and 143Nd/144Nd ratios of the Karacadaǧ and Tendürek lavas range from 0.703512 to 0.704466; 0.512742 to 0.512883 and 0.705743 to 0.705889 and 0.512676, respectively. Petrogenetic modelling has been used to constrain source characteristics for the central and eastern Anatolian volcanic rocks. Trace element ratio plots and REE modelling indicate that the central Anatolian volcanism was generated from a lithospheric mantle source that recorded the previous subduction events between Afro-Arabian and Eurasian plates during Eocene to Miocene times. In contrast, The Karacadaǧ alkaline basaltic volcanism on the Arabian foreland is derived from an OIB-like mantle source with limited crustal contamination. Tendürek volcanism, located on thickened crust, north of the Bitlis thrust zone, derived from the lithospheric mantle via small degrees (1.5 %) of partial melting.
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Mahoney, J. Brian, Richard M. Friedman, and Sean D. McKinley. "Evolution of a Middle Jurassic volcanic arc: stratigraphic, isotopic, and geochemical characteristics of the Harrison Lake Formation, southwestern British Columbia." Canadian Journal of Earth Sciences 32, no. 10 (October 1, 1995): 1759–76. http://dx.doi.org/10.1139/e95-137.
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The Harrison Lake Formation is an Early to Middle Jurassic volcanic-arc assemblage unconformably overlying Triassic oceanic basement in the eastern Coast Belt of southwestern British Columbia. The formation is subdivided into four members including, in ascending order, the Celia Cove Member (conglomerate), the Francis Lake Member (fine-grained strata), the Weaver Lake Member (flows and breccias), and the Echo Island Member (pyroclastic and epiclastic strata). New biostratigraphic constraints pinpoint the initiation of volcanism to late early Toarcian. U–Pb geochronology demonstrates the arc was active until at least late Bajocian–early Bathonian time (166.0 ± 0.4 Ma), and that the timing of arc volcanism strongly overlaps emplacement of both hypabyssal intrusions (Hemlock Valley stock) and deep-seated plutons (Mount Jasper pluton) within and adjacent to the arc. Geochemical data indicate the arc is of medium- to high-K calc-alkaline affinity, and is strongly light rare earth element enriched (LaN/YbN = 1.5 – 2.5). Nd and Sr isotopic data from primary volcanic rocks demonstrate the juvenile nature of the magmatic system, but isotopic data from associated fine-grained sedimentary rocks suggest temporally controlled variations in isotopic composition interpreted to represent two-component mixing between juvenile volcanic detritus and a more evolved detrital component. The succession of facies in the Harrison Lake Formation records initial basin subsidence in the Early Jurassic, initiation of explosive volcanism in the late early Toarcian, a change to effusive volcanism in the early Aalenian, and late-stage explosive volcanism in the late Bajocian. The Harrison Lake Formation contains mesoscopic folds and overturned bedding that are absent in the overlying Callovian Mysterious Creek Formation, strongly suggesting the existence of a regional Bathonian deformational event in the southern Coast Belt.
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Dürig, Tobias, Ingo Sonder, Bernd Zimanowski, Hermann Beyrichen, and Ralf Büttner. "Generation of volcanic ash by basaltic volcanism." Journal of Geophysical Research: Solid Earth 117, B1 (January 2012): n/a. http://dx.doi.org/10.1029/2011jb008628.
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Vatrushkina, E. V., M. I. Tuchkova, and S. D. Sokolov. "Suprasubduction volcanism of Chukotka terrane in the late jurassic– early cretaceous (Arctic region, Russia)." Геотектоника, no. 6 (November 17, 2019): 78–91. http://dx.doi.org/10.31857/s0016-853x2019678-91.
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Abstract The age and geodynamic position of the volcanic source of the Upper JurassicLower Cretaceous deposits of Western Chukotka were determined. Products of synchronous volcanism were revealed by detailed lithological studies. Following sedimentological analysis results we established an admixture of pyroclastic material in the Oxford-Kimmeridgian deposits of the Chukotka microcontinent, indicating the effect of synchronous volcanism on sedimentation. It was shown that the source of pyroclastic material was the intraoceanic Kulpolney island arc, which existed in the northern part of the Proto-Arctic Ocean.The accumulation of the Tithonian‒ Valanginian deposits occurred in the back-arc basin at the edge of Chukotka microcontinent. Characteristics of the Tithonian‒ Berriasian sandstones are given, which contain significant proportion of ash material in the matrix, as well as lithoclasts and monomineral grains of volcanic origin, predominant in the clasts. With the use of geochemical analysis of volcanic pebbles, the presence of the differentiated series from basaltic andesites to rhyolites in the volcanic source is proved.
The suprasubduction origin of the volcanic source is established. The cessation of volcanic activity in Valangin era is confirmed by lack of presence of synchronous pyroclastic material and an insignificant amount of volcanic clasts in Valanginian sandstones. The obtained data of UPb isotope dating of zircons isolated from the Tithonian-Valanginian sandstones and andesite pebbles of the Tithonian conglomerates made it possible to determine the time for the existence of suprasubduction volcanism on the Chukotka margin in the period of 150140 Ma.
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Calleja, Hannah, and Tom Pering. "Crystals and inclined conduits: analogue experiments for slug-driven volcanism." Volcanica 6, no. 1 (June 27, 2023): 147–60. http://dx.doi.org/10.30909/vol.06.01.147160.
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Basaltic volcanism is the dominant mode of volcanism on Earth and exhibits a range of activity, from passive degassing to the most common explosive style: strombolian volcanism. Strombolian volcanism is driven by gas slugs, making it vital to consider the effects of variable magmatic rheology and internal vent geometry on slug flow dynamics. Emerging experimental technologies play a major role in developing our understanding of the natural complexity of such basaltic systems. This study examines slug ascent within particle-free and particle-containing media experimentally across a range of inclinations. Dimensionless parameters are derived to describe specific flow characteristics at laboratory and volcanic scales, and to demonstrate the viability of current theoretical framework. Slug ascent is shown to be dependent on its morphology, which is a function of inclination, liquid viscosity, and related controlling characteristics i.e. particle fraction. Maxima for ascent velocities and associated dimensionless parameters occur within the range 40—60°.
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Sommer, Carlos Augusto, Felipe Padilha Leitzke, Evandro Fernandes de Lima, Carla Joana Santos Barreto, Jean Michel Lafon, Vinicius Matté, Ruy Paulo Philipp, Rommulo Vieira Conceição, and Miguel Ângelo Stipp Basei. "Zircon U-Pb geochronology, Sm-Nd and Pb-Pb isotope systematics of Ediacaran post-collisional high-silica Acampamento Velho volcanism at the Tupanci area, NW of the Sul-Rio-Grandense Shield, Brazil." Brazilian Journal of Geology 47, no. 4 (December 2017): 545–60. http://dx.doi.org/10.1590/2317-4889201720170064.
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ABSTRACT: We present new U-Pb zircon ages and Sm-Nd-Pb isotopic data for volcanic and hypabyssal acid rocks from the northernmost exposure of the Acampamento Velho Formation in the NW portion of the Sul-Rio-Grandense Shield, Brazil. The first volcanic episode, grouped in the high-Ti rhyolites from the Tupanci hill, shows age of 579 ± 5.6 Ma, which is in agreement with the post-collisional Acampamento Velho Formation volcanism in the Bom Jardim Group of the Camaquã Basin. A poorly constrained age of 558 +/- 39 Ma was obtained for rhyolites from the low-Ti group at the Picados Hill, which may indicate a younger acid volcanism, or a greater time span for the volcanism of the Acampamento Velho Formation in southernmost Brazil. Regarding magmatic sources, Sm/Nd isotopic data coupled to Pb isotopes and a review of trace element geochemistry indicate different amounts of Paleoproterozoic (Dom Feliciano, Pinheiro Machado Suite) to Neoproterozoic (Rio Vacacaí terrane) lower crust melting. Our data, coupled with literature data, contribute to a better understanding of the stratigraphic evolution for the Neoproterozoic post-collisional volcanic successions of the Camaquã Basin in the Sul-Rio-Grandense Shield.
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Bordet, Esther, Mitchell G. Mihalynuk, Craig J. R. Hart, Jim K. Mortensen, Richard M. Friedman, and Janet Gabites. "Chronostratigraphy of Eocene volcanism, central British Columbia." Canadian Journal of Earth Sciences 51, no. 1 (January 2014): 56–103. http://dx.doi.org/10.1139/cjes-2013-0073.
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Onset and termination of Eocene felsic volcanism in the Chilcotin Plateau of central British Columbia is constrained between 54.6 and 46.6 Ma by 33 new U–Pb and 40Ar/39Ar isotopic age determinations. Dates were obtained from representative felsic coherent and fragmental volcanic rocks that comprise the Ootsa Lake Group. The resulting chronostratigraphy shows that magma compositions evolved from felsic to intermediate, with no spatial migration of the volcanic activity. Rhyolitic compositions are oldest; and are overlain by dacitic rocks with varied phenocrysts assemblages. In many parts of the Chilcotin Plateau, the Eocene stratigraphy is capped by distinctive vitreous black dacite lavas, which are contemporaneous with andesitic lavas of the Endako Group in the Nechako Plateau to the north. Crystallization ages from Ootsa Lake Group rocks of the Chilcotin Plateau overlap age determinations from correlative rocks of the Nechako Plateau and southern BC. Collectively, this geochronological dataset supports previous suggestions of a voluminous Early Eocene-aged (∼55–46 Ma) period of volcanism in the Intermontane Belt. The abrupt initiation of volcanism, as well as the wide extent, thickness, and compositions that characterize Eocene volcanic rocks may be explained by cessation of subduction and formation of a slab gap beneath British Columbia in the Early Eocene.
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Monjoie, Philippe, Henriette Lapierre, Artan Tashko, Georges H. Mascle, Aline Dechamp, Bardhyl Muceku, and Pierre Brunet. "Nature and origin of the Triassic volcanism in Albania and Othrys: a key to understanding the Neotethys opening?" Bulletin de la Société Géologique de France 179, no. 4 (July 1, 2008): 411–25. http://dx.doi.org/10.2113/gssgfbull.179.4.411.
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AbstractTriassic volcanic rocks, stratigraphically associated with pelagic or reef limestones, are tectonically juxtaposed with Mesozoic ophiolites in the Tethyan realm. From the central (Dinarides, Hellenides) and eastern Mediterranean (Antalya, Troodos, Baër Bassit) to the Semail nappes (Oman), they occur either associated to the tectonic sole of the ophiolitic nappes or as a distinct tectonic pile intercalated between the ophiolites and other underthrust units. In the Dinaro-Hellenic belt, the Pelagonian units represent the lower plate, which is underthrust beneath the ophiolites. Middle to Late Triassic volcanic sequences are interpreted as the eastern flank of the Pelagonian platform and are therefore considered as a distal, deep-water part of the Pelagonian margin.The Triassic volcanics from Albania and Othrys are made up of basaltic pillowed and massive flows, associated locally with dolerites and trachytes. New elemental, Nd and Pb isotopic data allow to recognize four types of volcanic suites: (1) intra-oceanic alkaline and tholeiitic basalts, (2) intra-oceanic arc-tholeiites, (3) back-arc basin basalts, (4) calc-alkaline mafic to felsic rocks. Nd and Pb isotopic initial ratios suggest that the within-plate volcanic rocks were derived from an enriched oceanic island basalt type mantle source, devoid of any continental crustal component. The lower εNd value of the trachyte could be due to assimilation of oceanic altered crust or sediments in a shallow magma chamber. Island arc tholeiites and back-arc basin basalts have a similar wide range of εNd. The absence of Nb negative anomalies in the back-arc basin basalts suggests that the basin floored by these basalts was wide and mature. The high Th contents of the island arc tholeiites suggest that the arc volcanoes were located not far away from the continental margin.Albania and Othrys volcanics contrast with the Late Triassic volcanism from eastern Mediterranean (SW Cyprus, SW Turkey), which displays solely features of oceanic within plate suites. The presence of back-arc basin basalts associated with arc-related volcanics in Central Mediterranean indicates that they were close to a still active subduction during the Upper Triassic, while back-arc basins developed, associated with within-plate volcanism, leading to the NeoTethys opening.
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Zielinski, Gregory A., Paul A. Mayewski, L. David Meeker, S. Whitlow, and Mark S. Twickler. "A 110,000-Yr Record of Explosive Volcanism from the GISP2 (Greenland) Ice Core." Quaternary Research 45, no. 2 (March 1996): 109–18. http://dx.doi.org/10.1006/qres.1996.0013.
Full textAbstract:
AbstractThe time series of volcanically produced sulfate from the GISP2 ice core is used to develop a continuous record of explosive volcanism over the past 110,000 yr. We identified ∼850 volcanic signals (700 of these from 110,000 to 9000 yr ago) with sulfate concentrations greater than that associated with historical eruptions from either equatorial or mid-latitude regions that are known to have perturbed global or Northern Hemisphere climate, respectively. This number is a minimum because decreasing sampling resolution with depth, source volcano location, variable circulation patterns at the time of the eruption, and post-depositional modification of the signal can result in an incomplete record. The largest and most abundant volcanic signals over the past 110,000 yr, even after accounting for lower sampling resolution in the earlier part of the record, occur between 17,000 and 6000 yr ago, during and following the last deglaciation. A second period of enhanced volcanism occurs 35,000–22,000 yr ago, leading up to and during the last glacial maximum. These findings further support a possible climate-forcing component in volcanism. Increased volcanism often occurs during stadial/interstadial transitions within the last glaciation, but this is not consistent over the entire cycle. Ages for some of the largest known eruptions 100,000–9000 yr ago closely correspond to individual sulfate peaks or groups of peaks in our record.
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Riley, Teal R., and Kim B. Knight. "Age of Pre-Break-Up Gondwana Magmatism." Antarctic Science 13, no. 2 (June 2001): 99–110. http://dx.doi.org/10.1017/s0954102001000177.
Full textAbstract:
Extensive outpourings of basalt, and to a lesser extent rhyolite, are closely associated with continental break-up and plume–lithosphere interactions. The Gondwana supercontinent began to fragment during Early–Middle Jurassic times and was associated with the eruption of over three million km3 of dominantly basaltic magma. This intense magmatic episode is recorded in volcanic rocks of the Karoo (Africa), Ferrar (Antarctica) and Chon Aike (South America). K–Ar and Rb–Sr whole rock geochronology has consistently failed to produce reliable ages for these volcanic rocks, but in the last four years, the wider application of single grain 40Ar/39Ar and/or U–Pb geochronology has produced more robust and precise dating of the magmatism. This paper reviews the recent advances in high precision geochronology and provides a full recalibrated 40Ar/39Ar dataset. Application of these methods across the majority of the volcanic provinces indicates that approximately 80% of the volcanic rocks were erupted within a short, 3–4 Myr period at c. 182 Ma. This burst of magmatism occurred in the Karoo province at c. 183 Ma and in the Ferrar provinces at c. 180 Ma, and was dominated by mafic volcanism. This peak in volcanism is coincident with a second order mass extinction event at the end of the Pliensbachian when c. 5% of marine families were wiped out coinciding with widespread oceanic anoxia in the early Toarcian. A prolonged period of silicic volcanism occurred along the proto-Pacific margin, prior to, and during the main phase of break-up. Silicic volcanism was initially coincident with the plume related Karoo-Ferrar provinces, but continued over c. 40 Myr, associated with lithospheric extension and subduction along the proto-Pacific continental margin.
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Palmer, M. R., E. Y. Ersoy, C. Akal, İ. Uysal, Ş. C. Genç, L. A. Banks, M. J. Cooper, J. A. Milton, and K. D. Zhao. "A short, sharp pulse of potassium-rich volcanism during continental collision and subduction." Geology 47, no. 11 (September 23, 2019): 1079–82. http://dx.doi.org/10.1130/g45836.1.
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Abstract Potassic volcanic rocks are characteristic of collisional tectonic zones, with recycling of continental crust playing an important role in their generation. Potassium-rich partial melts and/or fluids derived from subducted continental material initiate and/or mix with mantle-derived melts and then erupt at the surface with varying degrees of interaction with the overlying lithosphere. The details of how continental material incorporates into mantle melts are, however, uncertain. In particular, the depths from which the potassium-rich fluids and/or melts are released from the continental material and then react with the mantle-derived melts remain a subject of debate. We have measured the boron isotope composition of volcanic rocks from Western Anatolia (Turkey) that erupted between 52 and 0.1 Ma, and span the lifetime of collisional events from initial arc-type eruptions to post-collisional volcanism. These data and other geochemical indices show that ultrapotassic volcanism was mainly confined to a narrow window between ca. 20 and 15 Ma, consistent with recycling of high-pressure phengite, with the timing of the potassic volcanism coincident with slab rollback and breakoff.
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Ludman, Allan, Christopher McFarlane, and Amber T. H. Whittaker. "Age, chemistry, and tectonic setting of Miramichi terrane (Early Paleozoic) volcanic rocks, eastern and east-central Maine, USA." Atlantic Geology 57 (November 11, 2021): 239–73. http://dx.doi.org/10.4138/atlgeol.2021.012.
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Volcanic rocks in the Miramichi inlier in Maine occur in two areas separated by the Bottle Lake plutonic complex: the Danforth segment (Stetson Mountain Formation) north of the complex and Greenfield segment to the south (Olamon Stream Formation). Both suites are dominantly pyroclastic, with abundant andesite, dacite, and rhyolite tuffs and subordinate lavas, breccias, and agglomerates. Rare basaltic tuffs and a small area of basaltic tuffs, agglomerates, and lavas are restricted to the Greenfield segment. U–Pb zircon geochronology dates Greenfield segment volcanism at ca. 469 Ma, the Floian–Dapingian boundary between the Lower and Middle Ordovician. Chemical analyses reveal a calc-alkaline suite erupted in a continental volcanic arc, either the Meductic or earliest Balmoral phase of Popelogan arc activity. The Maine Miramichi volcanic rocks are most likely correlative with the Meductic Group volcanic suite in west-central New Brunswick. Orogen-parallel lithologic and chemical variations from New Brunswick to east-central Maine may result from eruptions at different volcanic centers. The bimodal Poplar Mountain volcanic suite at the Maine–New Brunswick border is 10–20 myr younger than the Miramichi volcanic rocks and more likely an early phase of back-arc basin rifting than a late-stage Meductic phase event. Coeval calc-alkaline arc volcanism in the Miramichi, Weeksboro–Lunksoos Lake, and Munsungun Cambrian–Ordovician inliers in Maine is not consistent with tectonic models involving northwestward migration of arc volcanism. This >150 km span cannot be explained by a single east-facing subduction zone, suggesting more than one subduction zone/arc complex in the region.
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UYANIK, Nurten Ayten. "An Approach to Determine of the Formation Stages of Volcanism Using Natural Gamma-Ray Spectrometer from Geophysical Methods (Example of Gölcük Volcanism)." Bitlis Eren Üniversitesi Fen Bilimleri Dergisi 12, no. 2 (April 7, 2023): 455–64. http://dx.doi.org/10.17798/bitlisfen.1239935.
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Gölcük Caldera is in the Isparta Angle, which is an interesting tectonic structure in Southwest Anatolia. This caldera is formed as a result of back-arc volcanism associated with the northward subduction zone of the African plate under the Eurasian Plate during the Tertiary. It attracts the attention of many researchers with its tectonic and volcanic structure. In this article, the results of in situ natural gamma radiation measurements made in the caldera are evaluated. In the study, radioactive element (Potassium (%K), Uranium (eU), and Thorium (eTh)) contents of volcanics were measured in situ with the portable gamma-ray spectrometer, which is effectively used in Geophysical Engineering. The changes in natural gamma radiation of alkaline volcanic are presented with maps. When these maps are examined, it is understood that K%, U-ppm and Th-ppm concentrations of Gölcük volcanic are higher than the world average values. The high potassium concentration draws even more attention. The high potassium content indicates that the local volcanic are ultrapotassic and contain lithospheric materials. In addition, since the radioactive element concentration will reflect the magmatic development, the volcanic stages in the region have been tried to be determined. The number of these stages was determined from the curves of the radioactive data from a purely geophysical engineering (numerical) point of view, and the study area was interpreted as consisting of three different phases. This finding is supported by the results of the articles on the aging studies of the samples taken as a result of observations. In addition to these, the ranges of radioactive elements belonging to these stages were determined.
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Mortensen, J. K. "U–Pb geochronology of the eastern Abitibi Subprovince. Part 2: Noranda – Kirkland Lake area." Canadian Journal of Earth Sciences 30, no. 1 (January 1, 1993): 29–41. http://dx.doi.org/10.1139/e93-003.
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U–Pb zircon ages for 15 volcanic and plutonic units in the Noranda and Kirkland Lake areas help constrain the history of volcanism, plutonism, sedimentation, and deformation in the south-central part of the Abitibi belt. Volcanism occurred over an interval of at least 50 Ma, beginning with the deposition of the volcanic and volcaniclastic units within the Pacaud Structural Complex at 2747 Ma. Following a period of apparent quiescence, magmatism resumed at 2730–2725 Ma with the eruption of volcanic rocks in the Normétal and Lac Abitibi area. From 2715 until about 2698 Ma, volcanism occurred sporadically throughout much of the area, culminating in the eruption of the Blake River Group from 2703 to 2698 Ma. Several large intrusive bodies yield ages that indicate that they are plutonic equivalents of the Blake River Group. Plutons that are considered to have been emplaced during the Kenoran orogeny give ages that are only slightly younger than the youngest volcanic units of the Blake River Group, emphasizing the very rapid onset of Kenoran deformation following the cessation of volcanic activity.The Cléricy syenite, dated at 2682 ± 3 Ma, postdates the main period of Kenoran deformation in this area and intrudes sedimentary rocks of the Kewagama Group which contain detrital zircons as young as 2687 Ma. These data suggest that the Kewagama Group is the same age as late sedimentary sequences such as the Timiskaming Group and may have been deposited in a similar tectonic setting.
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Che, Xiaochao, Alexander Nemchin, Dunyi Liu, Tao Long, Chen Wang, Marc D. Norman, Katherine H. Joy, et al. "Age and composition of young basalts on the Moon, measured from samples returned by Chang’e-5." Science 374, no. 6569 (November 12, 2021): 887–90. http://dx.doi.org/10.1126/science.abl7957.
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Sample return shows late lunar volcanism Measuring physical samples of Solar System bodies in the laboratory provides more information than is possible from remote sensing alone. In December 2020, the Chang’e-5 mission landed on the Moon, collected samples, and returned them to Earth. Che et al . analyze two fragments of volcanic lunar basalt collected by Chang’e-5. Radiometric dating using lead isotopes indicated that the rocks formed from magma that erupted about 2 billion years ago, later than other volcanic lunar samples. The abundance of extinct radioactive elements in the rock is too low for radioactive heating to have produced the magma. Another, thus far unknown, source must be responsible for the late lunar volcanism. —KTS