Journal articles: 'Carbonate U-Pb dating'

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Tartèse, Romain, and Ian C. Lyon. "In situ U–Pb dating of 4 billion-year-old carbonates in the martian meteorite Allan Hills 84001." Geochronology 4, no. 2 (December 6, 2022): 683–90. http://dx.doi.org/10.5194/gchron-4-683-2022.

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Abstract. In situ carbonate U–Pb dating studies have proliferated dramatically in recent years. Almost all these studies have targeted relatively young terrestrial calcite up to Carboniferous in age. To assess the robustness of the carbonate U–Pb chronometer in deep time, we carried out in situ U–Pb analyses in magnesite–ankerite–calcite carbonates in the martian meteorite Allan Hills (ALH) 84001. Carbonates in ALH 84001 formed at ca. 3.94 Ga, and there is little evidence that much happened to this rock since then, making it an ideal sample to test the robustness of the U–Pb system in old carbonates. We obtained a concordant date of 3941 ± 49/110 Ma (n=14, MSWD = 2.0), which is identical to the step-leaching Rb/Sr date determined previously. These results thus confirm that old carbonates are amenable to U–Pb dating in samples that have had a relatively simple history post-carbonate formation.

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Roberts, Nick M. W., Kerstin Drost, Matthew S. A. Horstwood, Daniel J. Condon, David Chew, Henrik Drake, Antoni E. Milodowski, et al. "Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb carbonate geochronology: strategies, progress, and limitations." Geochronology 2, no. 1 (April 9, 2020): 33–61. http://dx.doi.org/10.5194/gchron-2-33-2020.

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Abstract. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb geochronology of carbonate minerals, calcite in particular, is rapidly gaining popularity as an absolute dating method. The high spatial resolution of LA-ICP-MS U–Pb carbonate geochronology has benefits over traditional isotope dilution methods, particularly for diagenetic and hydrothermal calcite, because uranium and lead are heterogeneously distributed on the sub-millimetre scale. At the same time, this can provide limitations to the method, as locating zones of radiogenic lead can be time-consuming and “hit or miss”. Here, we present strategies for dating carbonates with in situ techniques, through imaging and petrographic techniques to data interpretation; our examples are drawn from the dating of fracture-filling calcite, but our discussion is relevant to all carbonate applications. We review several limitations to the method, including open-system behaviour, variable initial-lead compositions, and U–daughter disequilibrium. We also discuss two approaches to data collection: traditional spot analyses guided by petrographic and elemental imaging and image-based dating that utilises LA-ICP-MS elemental and isotopic map data.

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Beranoaguirre, Aratz, Iuliana Vasiliev, and Axel Gerdes. "In situ LA-ICPMS U–Pb dating of sulfates: applicability of carbonate reference materials as matrix-matched standards." Geochronology 4, no. 2 (September 6, 2022): 601–16. http://dx.doi.org/10.5194/gchron-4-601-2022.

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Abstract. Recent developments in analytical capabilities in the field of in situ laser ablation mass spectrometry (LA-ICPMS) have expanded the applications of U–Pb geochronometers in low-U minerals such as carbonates or garnets. The rapid evolution of the technique relies on well-characterized matrix-matched reference materials. In this article, we explore the suitability of using carbonate as an “almost-matrix-matched reference material” for in situ U–Pb dating of sulfates. For such purpose, we have used the astrochronologically dated gypsum and anhydrite samples deposited during the Messinian Salinity Crisis (5.97–5.33 Ma) and compared these dates with the U–Pb ages obtained by LA-ICPMS. Although the majority of the samples failed due to the elevated common Pb content and low 238U/204Pb ratios, five of the samples showed a higher dispersion on U/Pb ratios. The obtained dates in four of these samples are comparable with the expected ages, while another gave an unexpected younger age, each of them with 6 %–11 % of uncertainty. The pit depth of the spots showed that the sulfates ablate similar to carbonates, so the offset due to the crater geometry mismatch or downhole fractionation can be assumed to be negligible. To sum up, the bias between the U–Pb and expected cyclostratigraphic ages, if any, is included in the uncertainty, and thus the results obtained here suggest that carbonate reference material is currently the best option for standardization of in situ U–Pb sulfate analyses.

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Rasbury, E. Troy, Theodore M. Present, Paul Northrup, Ryan V. Tappero, Antonio Lanzirotti, Jennifer M. Cole, Kathleen M. Wooton, and Kevin Hatton. "Tools for uranium characterization in carbonate samples: case studies of natural U–Pb geochronology reference materials." Geochronology 3, no. 1 (February 16, 2021): 103–22. http://dx.doi.org/10.5194/gchron-3-103-2021.

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Abstract. Laser ablation U–Pb analyses of carbonate (LAcarb) samples has greatly expanded the potential for U–Pb dating to a variety of carbonate-producing settings. Carbonates that were previously considered impossible to date using isotope dilution methods may preserve radiogenic domains that can be dated using spatially resolved laser ablation geochronology techniques. Work is ongoing to identify reference materials and to consider best practices for LAcarb. In this study we apply standard and emerging characterization tool sets on three natural samples with the dual goal of enhancing the study of carbonates and establishing a new set of well-characterized natural reference materials for LAcarb studies. We start with the existing carbonate reference material WC-1 from the Permian Reef Complex of Texas, building on the published description to offer a deeper look at U and associated trace elements. We consider a tufa sample from the Miocene Barstow Formation of the Mojave Block, California, as a possible secondary calcite reference material due to its well-behaved U–Pb systematics. There are currently no natural dolomite standards. We present an unusual dolomite sample with very well-behaved U–Pb systematics from the Miocene of the Turkana Basin of Kenya as a possible dolomite reference material for LAcarb dating. In addition to using X-ray fluorescence (XRF) mapping and spectroscopy to better understand U in these natural samples, we have analyzed multiple aliquots of each of them for 87Sr/86Sr by thermal ionization mass spectrometry (TIMS). The Sr isotope compositions are analytically homogeneous within petrographically homogeneous regions of all three samples, and thus these materials could be used as Sr isotope standards as well. While not part of the current contribution, this combination could streamline simultaneous LA analyses of 87Sr/86Sr and U–Pb geochronology.

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Winter, Bryce L., and Clark M. Johnson. "UPb dating of a carbonate subaerial exposure event." Earth and Planetary Science Letters 131, no. 3-4 (April 1995): 177–87. http://dx.doi.org/10.1016/0012-821x(95)00026-9.

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Vetrova, N. I., E. V. Vetrov, and E. F. Letnikova. "СHEMOSTRATIGRAPHY OF THE CARBONATE DEPOSITS OF THE KINTEREP FORMATION IN NORTHWESTERN SALAIR: FIRST DATA." Geology and mineral resources of Siberia, no. 2 (June 2022): 10–23. http://dx.doi.org/10.20403/2078-0575-2022-2-10-23.

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The results of geochemical, isotope-geochemical (Sr, C, O) surveys of the Kinterep Formation carbonate deposits of Northwestern Salair and U-Pb dating (LA-ICP-MS) of zircons were given. Carbonate rocks represented by pure limestones are characterized by normal values of δ18OSMOW from 19.8 to 23.8 ‰ and δ13 CPDB from –0.7 to +0.9, the isotopic composition of Sr (87Sr/86Sr ratio) varies in a narrow range from 0.708486 to 0.708582.Using Sr and C isotope chemostratigraphy and U-Pb dating of zircons, age limits (525-510 Ma) were determined for the formation time of carbonate deposits of the Kinterep Formation. The first data of isotope chemostratigraphy in combination with the results of geochronological studies made it possible to compare the limestones of the Kinterep Formation of Northwestern Salair with carbonate sections of Siberia and Central Asia.

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Woodhead, Jon, and Joseph Petrus. "Exploring the advantages and limitations of in situ U–Pb carbonate geochronology using speleothems." Geochronology 1, no. 1 (December 5, 2019): 69–84. http://dx.doi.org/10.5194/gchron-1-69-2019.

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Abstract. The recent development of methods for in situ U–Pb age determination in carbonates has found widespread application, but the benefits and limitations of the method over bulk analysis (isotope dilution – ID) approaches have yet to be fully explored. Here we use speleothems – cave carbonates such as stalagmites and flowstones – to investigate the utility of in situ dating methodologies for “challenging” matrices with typically low U and Pb contents and predominantly late Cenozoic ages. Using samples for which ID data have already been published, we show that accurate ages can be obtained for many speleothem types by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Consideration of our own and literature data suggest that most carbonates with >1 ppm uranium and a few hundred parts per billion of Pb should be good targets for in situ methodologies, regardless of age. In situ analysis often provides a larger spread in U∕Pb ratios, which can be advantageous for isochron construction, but isochron ages rarely achieve the ultimate precision of ID analyses conducted on the same samples simply because signal sizes are dramatically reduced. LA analysis is faster than ID and thus will play a significant role in reconnaissance studies. The major advantage of the in situ methodology appears to be the potential for successful dating outcomes in sample types requiring high spatial-resolution analysis or those with a high common-Pb component where LA approaches may facilitate identification of the most radiogenic regions for analysis.

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Letnikova, E. F., A. A. Zhdanov, A. V. Ivanov, A. V. Maslov, A. E. Izokh, A. F. Letnikova, and N. G. Soloshenko. "Sr-ISOTOPIC COMPOSITION OF PALEOOCEAN WATER ON THE BORDER OF 960 Ma (DATA FOR NIZHNY TUNGUSKA FORMATION OF TURUKHAN UPLIFT OF SIBERIAN PLATFORM)." Доклады Российской академии наук. Науки о Земле 513, no. 1 (November 1, 2023): 66–76. http://dx.doi.org/10.31857/s2686739723600960.

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At the boundary of the Meso- and Neoproterozoic, Grenville collision events were widely manifested on the margins of ancient continental blocks. Most of the sedimentary sequences that had accumulated by that time had undergone significant thermal–metamorphic changes. In many ways, this is the main reason for the lack of isotopic data for carbonate deposits in the interval of 1200–900 Ma in world practice. Sr–isotopic composition in carbonate rocks with an age of 980–920 Ma was determined in the only section of the World – the Huainan Formation of the North China Platform with accumulation time determined by U–Pb dating of detrital zircon grains. In the upper part of the Nizhny Tunguska suite of the Turukhansk uplift, among carbonate deposits, we established the presence of altered volcanic rocks, as well as weathering crust products along them – poor bauxite and chamosite ores. Based on U–Pb zircon isotope dating, the age of the volcanic rocks is 964 Ma. For the least altered limestones of the upper part of the Nizhny Tungusska Formation, received 87Sr/86Sr values are 0.70532–0.70578, which are close enough to those found in the rocks of the Huainan Formation. Geochronological age of the studied limestones gives us more correct data. These data can be used to refine the previously proposed configuration of the Sr–isotopic composition variation curve in the Early Neoproterozoic. The Nizhny Tunguska Formation is the only carbonate section of the Early Neoproterozoic in the world with correctly geochronologically substantiated dating (based on zircon from subsynchronous volcanic rocks). This compares favorably with the Huainan formation.

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Wei, Zhenquan, Jinfeng Ma, Gaowen He, Lifeng Zhong, Limin Zhang, and Bin Zhao. "Laser In Situ U–Pb Isotope Dating of Carbonate Rocks in Weijia Guyot in the Western Pacific Ocean and Its Geological Significance." Journal of Marine Science and Engineering 12, no. 5 (April 28, 2024): 737. http://dx.doi.org/10.3390/jmse12050737.

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Shallow-water carbonate rocks constitute a crucial component of large guyots, arising in distinct environments and harboring valuable insights into the evolutionary stages of seamount islands as well as the tectonic conditions of the underlying oceanic plate. Laser Ablation Multi-Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) was used to conduct in situ U–Pb isotope dating of carbonate minerals with low uranium content collected from Weijia Guyot. This dating approach yielded crucial evidence for the vertical development of the seamount. Our study indicates that shallow-water carbonate rocks in Weijia Guyot had a temporal range between 91 My and 137 My. The carbonate rocks underwent two growth phases, Hauterivian to Barremian and Cenomanian to Turonian, with a hiatus of approximately 20 My. Since the Hauterivian age, the shield volcano of Weijia Guyot is essentially complete, with its seamount top exposed at or near sea level and receiving its first stage of shallow-water carbonate sedimentation. Based on the dating of both shallow-water carbonate rocks and hawaiite within the Weijia Guyot, it is inferred that approximately 10 My elapsed from shield-building volcanism to late alkalic volcanism. During the Turonian age, the main reason for the second phase of shallow-water carbonate rocks in the seamounts was the regional tectonic uplift triggered by the drift of the Weijia Guyot along with the Pacific Plate toward the Society hotspot.

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Drost, Kerstin, David Chew, Joseph A. Petrus, Frank Scholze, Jon D. Woodhead, Joerg W. Schneider, and David A. T. Harper. "An Image Mapping Approach to U-Pb LA-ICP-MS Carbonate Dating and Applications to Direct Dating of Carbonate Sedimentation." Geochemistry, Geophysics, Geosystems 19, no. 12 (December 2018): 4631–48. http://dx.doi.org/10.1029/2018gc007850.

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Lenoir, Louise, Thomas Blaise, Andréa Somogyi, Benjamin Brigaud, Jocelyn Barbarand, Claire Boukari, Julius Nouet, Aurore Brézard-Oudot, and Maurice Pagel. "Uranium incorporation in fluorite and exploration of U–Pb dating." Geochronology 3, no. 1 (April 19, 2021): 199–227. http://dx.doi.org/10.5194/gchron-3-199-2021.

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Abstract. The age of ore deposits constitutes a decisive element in understanding their formation. Deciphering their precise chronology may be a challenge in the absence of mineral phases that can be dated by conventional geochronometers. Fluorite is very common either as the major or accessory mineral in a wide variety of ores and may provide information regarding the origin and timing of mineralizing fluid flows. In this contribution, we explore U–Pb dating on fluorite crystals from the world-class carbonate strata-bound fluorite ore of Pierre-Perthuis in Burgundy (Morvan massif, France). The uranium distribution within fluorite is mapped using induced fission-track and synchrotron radiation X-ray fluorescence nano-imaging, showing that higher U content is measured in an overgrowth of fluorite (Flog) as a discrete band. Preservation of a micrometer-thick zonation in U, associated with other substituted elements such as Sr, Y, Fe and Zr, implies that neither solid-state diffusion nor dissolution–recrystallization occurred. These U-bearing external fluorite overgrowths contain solid inclusions of about 30 µm globular pyrite crystals with a mean δ34S of −23.6 ± 0.4 ‰V-CDT. We propose that the U incorporation in the fluorite lattice results from the development of a redox front during bacterial sulfate reduction. Flog generation sampled and analyzed by laser ablation–inductively coupled plasma mass spectrometry (LA-ICP-MS) on four different crystals provides identical U–Pb ages within the limits of analytical uncertainty. Considered altogether, these four crystals yield an age estimate of 40.0 ± 1.7 Ma, not corrected for matrix-related elemental fractionation. Our results show that fluorite LA-ICP-MS U–Pb geochronology has potential for dating distinct crystal growth stages, although further research should be conducted to evaluate its accuracy.

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Engel, John, Roland Maas, Jon Woodhead, Jan Tympel, and Alan Greig. "A single-column extraction chemistry for isotope dilution U-Pb dating of carbonate." Chemical Geology 531 (January 2020): 119311. http://dx.doi.org/10.1016/j.chemgeo.2019.119311.

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Nuriel, Perach, Jörn-Frederik Wotzlaw, Maria Ovtcharova, Anton Vaks, Ciprian Stremtan, Martin Šala, Nick M. W. Roberts, and Andrew R. C. Kylander-Clark. "The use of ASH-15 flowstone as a matrix-matched reference material for laser-ablation U − Pb geochronology of calcite." Geochronology 3, no. 1 (January 14, 2021): 35–47. http://dx.doi.org/10.5194/gchron-3-35-2021.

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Abstract. Latest advances in laser ablation inductively coupled plasma mass spectrometer (LA-ICPMS) allow for accurate in situ U−Pb dating of carbonate material, with final age uncertainties usually >3 % 2σ. Cross-laboratory reference materials (RMs) used for sample-bracketing are currently limited to WC1 calcite with an age of 254.4±6.5 (2σ). The minimum uncertainty on any age determination with the LA-ICPMS method is therefore ≥2.5 %, and validation by secondary RMs is usually performed on in-house standards. This contribution presents a new reference material, ASH-15, a flowstone that is dated here by isotope dilution (ID) thermal ionization mass spectrometry (TIMS) analysis using 37 sub-samples, 1–7 mg each. Age results presented here are slightly younger compared to previous ID isotope ratio mass spectrometry (IRMS) U−Pb dates of ASH-15 but within uncertainties and in agreement with in situ analyses using WC1 as the primary RM. We provide new correction parameters to be used as primary or secondary standardization. The suggested 238U∕206Pb apparent age, not corrected for disequilibrium and without common-lead anchoring, is 2.965±0.011 Ma (uncertainties are 95 % confidence intervals). The new results could improve the propagated uncertainties on the final age with a minimal value of 0.4 %, which is approaching the uncertainty of typical ID analysis on higher-U materials such as zircon. We show that although LA-ICPMS spot analyses of ASH-15 exhibit significant scatter in their isotopic ratios, the down-hole fractionation of ASH-15 is similar to that of other reference materials. This high-U (≈1 ppm) and low-Pb (<0.01 ppm) calcite is most appropriate as a reference material for other speleothem-type carbonates but requires more-sensitive ICP-MS instruments such as the new generation of single-collector and multi-collector ICP-MS. Reference materials with high-Pb and low-U or both low-U and low-Pb compositions are still needed to fully cover the compositional range of carbonate material but may introduce analytical challenges.

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Davis, D. W., C. N. Sutcliffe, A. M. Thibodeau, J. Spalding, D. Schneider, A. Cruden, J. Adams, A. Parmenter, M. Jensen, and Z. Zajacz. "Hydrochronology of a proposed deep geological repository for low- and intermediate-level nuclear waste in southern Ontario from U–Pb dating of secondary minerals: response to Silurian and Cretaceous events." Canadian Journal of Earth Sciences 57, no. 4 (April 2020): 464–76. http://dx.doi.org/10.1139/cjes-2019-0004.

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A record of fluid flow has been documented within a Paleozoic carbonate platform sequence by U–Pb dating of calcite in veins and vugs from rock core sampled through a shallowly dipping sequence of sedimentary rocks beneath the Bruce nuclear site, Ontario, Canada. Secondary calcite from >650 m deep Ordovician carbonate rocks yields a Silurian age of 434 ± 5 Ma possibly related to infiltration of seawater from overlying evaporitic basins as well as hydrothermal solutions that infiltrated from below. In contrast, near-surface Devonian rocks mostly give vein infill ages over the range of 80–100 Ma with evidence for younger infill down to 50 Ma. Vein calcite samples previously dated from surface outcrops of Ordovician carbonate exposed up to 500 km to the east yielded similar U–Pb ages. Coincidence of near-surface vein calcite ages indicates widespread vein emplacement synchronous with a change in direction of motion of the North American plate as well as possible erosional unroofing following passage of the region over the Great Meteor hotspot approximately 125 Myr ago. Deeper carbonate formations have remained apparently impermeable to post-Paleozoic disturbance despite these perturbations.

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Kaurova, O. K., G. V. Ovchinnikova, and I. M. Gorokhov. "U-Th-Pb systematics of precambrian carbonate rocks: Dating of the formation and transformation of carbonate sediments." Stratigraphy and Geological Correlation 18, no. 3 (June 2010): 252–68. http://dx.doi.org/10.1134/s0869593810030032.

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Bonev, Nikolay, Petyo Filipov, Raya Raicheva, Massimo Chiaradia, and Robert Moritz. "Detrital zircon age and Sr isotopic constraints for a Late Palaeozoic carbonate platform in the lower Rhodope thrust system, Pirin, SW Bulgaria." Geological Magazine 156, no. 12 (October 29, 2019): 2117–24. http://dx.doi.org/10.1017/s0016756819001183.

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AbstractWe focused on the Pirin–Pangeon–Thasos carbonate sequence of the Rhodope thrust system, combining Sr isotopes from marble with U–Pb dating of detrital zircons from interlayered schists with outcrop near the villages of Ilindentsi and Petrovo in Bulgaria. The youngest zircon age at Ilindentsi is 266 Ma, i.e. Middle Permian, while the youngest zircon at Petrovo yielded an age of 290 Ma, i.e. Early Permian. Strontium isotopes range from 0.707420 to 0.707653, and are consistent with a Middle Permian maximum depositional age. Middle Permian sedimentation of this carbonate platform most likely occurred along the Eurasian margin rather than the Gondwana margin.

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Mottram, C. M., D. A. Kellett, T. Barresi, H. Zwingmann, M. Friend, A. Todd, and J. B. Percival. "Syncing fault rock clocks: Direct comparison of U-Pb carbonate and K-Ar illite fault dating methods." Geology 48, no. 12 (August 19, 2020): 1179–83. http://dx.doi.org/10.1130/g47778.1.

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Abstract The timing of slip on brittle faults in Earth’s upper crust is difficult to constrain, and direct radiometric dating of fault-generated materials is the most explicit approach. Here we make a direct comparison between K-Ar dating of fault gouge clay (authigenic illite) and U-Pb dating of carbonate slickenfibers and veins from the same fault. We have dated fault generated materials from the Big Creek fault, a northwest-striking, dextral strike-slip fault system in Yukon Territory, Canadian Cordillera. Both methods yielded dates at ca. 73 Ma and ca. 60–57 Ma, representing at least two periods of fault slip that form part of a complex fault and fluid-flow history. The Cretaceous result lies within previous indirect estimates for major slip on the fault. The Paleocene–Eocene result coincides with the estimated timing of slip of the nearby Tintina and Denali faults, which are crustal-scale, northwest-striking dextral faults, indicating Big Creek fault reactivation during regional faulting. The coincidence of periods of carbonate-crystallizing fracturing and fluid flow with intervals of seismic, gouge-generating slip supports the fault valve model, where fault strength is mediated by fluid pressures, and fluid emplacement requires seismic pumping in otherwise impermeable aseismic fault zones. The reproducibility of slip periods for distinct fault-generated materials using different decay systems indicates that these methods provide complimentary results and can be reliably applied to date brittle fault slip, opening new opportunities for investigating fault conditions with associated mineralizing fluid events.

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Kim, Ha, Seongsik Hong, Chaewon Park, Jihye Oh, Jonguk Kim, and Yungoo Song. "Principle and Application of 'Image-mapping' in-situ U-Pb Carbonate Age-dating." Economic and Environmental Geology 56, no. 2 (April 30, 2023): 115–23. http://dx.doi.org/10.9719/eeg.2023.56.2.115.

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Montano, Damaris, Marta Gasparrini, Axel Gerdes, Giovanna Della Porta, and Richard Albert. "In-situ U-Pb dating of Ries Crater lacustrine carbonates (Miocene, South-West Germany): Implications for continental carbonate chronostratigraphy." Earth and Planetary Science Letters 568 (August 2021): 117011. http://dx.doi.org/10.1016/j.epsl.2021.117011.

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Zou, Yu, Donghua You, Bo Chen, Huamin Yang, Zhixing Tian, Dongna Liu, and Liyu Zhang. "Carbonate U-Pb Geochronology and Clumped Isotope Constraints on the Origin of Hydrothermal Dolomites: A Case Study in the Middle Permian Qixia Formation, Sichuan Basin, South China." Minerals 13, no. 2 (February 3, 2023): 223. http://dx.doi.org/10.3390/min13020223.

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Reservoirs in the dolomites of the Middle Permian Qixia Formation in the Sichuan Basin are currently important oil and gas exploration objects in China. However, the questions concerning the sources of the dolomitized fluids and the control factors of the Qixia hydrothermal dolomites remain unclear. In this study, the original hydrothermal dolomites (the replacement dolomites (RDs) and saddle dolomites (SDs)) from the Qixia Formation in the southwestern Sichuan Basin (the PR1 well and Baoxing section) were mainly examined using novel in situ carbonate U-Pb dating with clumped isotopes (∆47). Our results show that the U-Pb ages of the latest SDs from the PR1 well (located in the middle zone of the Emeishan large igneous province (ELIP) and distanced from the Orogenic Belt of Longmenshan) are 257.9–251.0 Ma, coincident with the period of main activity of the ELIP. Combined with the previous U-Pb dating, we propose that the high-temperature T∆47 (82.2–108.4 °C and 127.5–205.9 °C) recorded for SDs from the PR1 well and Baoxing section may have responded to ELIP activity and Longmenshan orogeny activity, respectively. In addition, in the entire southwestern Sichuan Basin, the RDs and SDs yield similar δ13C and δ18O values, indicating that the dolomites were formed by hydrothermal fluids of similar sources, with marine hydrothermal fluids being a highly possible source. Finally, this study proposes a new hydrothermal dolomite genesis model for the Qixia Formation, emphasizing that the formation of hydrothermal dolomites mainly depends on the proximity to tectonic thermal events in space and time.

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Jin, Xiao-Ye, Jian-Xin Zhao, Yue-Xing Feng, Albert H. Hofstra, Xiao-Dong Deng, Xin-Fu Zhao, and Jian-Wei Li. "CALCITE U-Pb DATING UNRAVELS THE AGE AND HYDROTHERMAL HISTORY OF THE GIANT SHUIYINDONG CARLIN-TYPE GOLD DEPOSIT IN THE GOLDEN TRIANGLE, SOUTH CHINA." Economic Geology 116, no. 6 (September 1, 2021): 1253–65. http://dx.doi.org/10.5382/econgeo.4870.

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Abstract The ages of Carlin-type gold deposits in the Golden Triangle of South China have long been questioned due to the general lack of minerals unequivocally linked to gold deposition that can be precisely dated using conventional radiogenic isotope techniques. Recent advances in U-Pb methods show that calcite can be used to constrain the ages of hydrothermal processes, but few studies have been applied to ore deposits. Herein, we show that this approach can be used to constrain the timing of hydrothermal activity that generated and overprinted the giant Shuiyindong Carlin-type gold deposit in the Golden Triangle. Three stages of calcite (Cal-1, Cal-2, and Cal-3) have been recognized in this deposit based on crosscutting relationships, cathodoluminescence colors, and chemical (U, Pb, and rare earth element [REE]) and isotope (C, O, Sr) compositions. Cal-1 is texturally associated with ore-stage jasperoid and disseminated Au-bearing arsenian pyrite in hydrothermally altered carbonate rocks, which suggests it is synmineralization. Cal-2 fills open spaces and has a distinct orange cathodoluminescence, suggesting that it precipitated during a second fluid pulse. Cal-1 and Cal-2 have similar carbonate rock-buffered chemical and isotopic compositions. Cal-3 occurs in veins that often contain realgar and/or orpiment and are chemically (low U, Pb, and REE) and isotopically (higher δ13C, lower δ18O and Sri values) distinct from Cal-1 and Cal-2, suggesting that it formed from a third fluid. U-Pb isotope analyses, by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) for U-rich Cal-1 and Cal-2 and by LA-multicollector (MC)-ICP-MS for U-poor Cal-3, yield well-defined age constraints of 204.3 to 202.6, 191.9, and 139.3 to 137.1 Ma for Cal-1, Cal-2, and Cal-3, respectively. These new ages suggest that the Shuiyindong gold deposit formed in the late Triassic and was overprinted by hydrothermal events in the early Jurassic and early Cretaceous. Given the association of Cal-3 with orpiment and realgar, and previous geochronologic studies of several other major gold deposits in the Golden Triangle, we infer that the latest stage of calcite may be associated with an early Cretaceous regional gold metallogenic event. Combined with existing isotopic ages in the region, these new ages lead us to propose that Carlin-type gold deposits in the Golden Triangle formed during two metallogenic episodes in extensional settings, associated with the late Triassic Indochina orogeny and early Cretaceous paleo-Pacific plate subduction. This study shows that the calcite U-Pb method can be used to constrain the timing of Carlin-type gold deposits and successive hydrothermal events.

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Scharf, Andreas, Christopher M. Bailey, Robert Bolhar, Frank Mattern, and Uwe Ring. "Post-obduction listwaenite genesis in the Oman Mountains inferred from structural analysis and U-Pb carbonate dating." Earth and Planetary Science Letters 595 (October 2022): 117756. http://dx.doi.org/10.1016/j.epsl.2022.117756.

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SHEN, Anjiang, Anping HU, Ting CHENG, Feng LIANG, Wenqing PAN, Yuexing FENG, and Jianxin ZHAO. "Laser ablation in situ U-Pb dating and its application to diagenesis-porosity evolution of carbonate reservoirs." Petroleum Exploration and Development 46, no. 6 (December 2019): 1127–40. http://dx.doi.org/10.1016/s1876-3804(19)60268-5.

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Ivanov, A. V., E. F. Letnikova, S. I. Shkolnik, A. V. Maslov, and N. I. Vetrova. "EARLY CAMBRIAN DEPOSITS OF THE CONTINENTAL MARGIN (SOUTH OF TUVA, TEREGTIG FORMATION): RESULTS OF U–Pb DATING OF DETRITAL ZIRCONS AND Sr-CHEMOSTRATIGRAPHY." Доклады Российской академии наук. Науки о Земле 512, no. 2 (October 1, 2023): 165–73. http://dx.doi.org/10.31857/s2686739722602034.

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The sedimentation interval (530–520 Ma) of the Teregtig Formation deposits in southern Tuva is estimated based on U–Pb dating of detrital zircons from terrigenous deposits and Sr-chemostratigraphy of carbonate rocks. The main source area for clastic material, containing a large amount of detrital zircon grains, were rocks with an age of 580 Ma. The presence of a wide diversity of Precambrian detrital zircons indicates that sedimentation of the Teregtig Formation took place within a block of continental crust with a long evolutionary history. The presence of numerous chromites in their matrix indicates that the rocks of the Agardag ophiolite complex were also part of the eroded land during the accumulation of conglomerates of the Teregtig Formation.

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Liang, Enyun, Dezhi Huang, Guangqian Zeng, Gengyin Liu, Guangjun Zou, Peng Luo, and Di Chen. "Metallogenesis of the Bawang Sn-Zn Polymetallic Deposit, Wuxu Ore Field, Guangxi, South China: U-Pb Dating and C-O-S-Pb Isotopic Constraints." Minerals 12, no. 2 (January 25, 2022): 137. http://dx.doi.org/10.3390/min12020137.

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The Bawang deposit, located in the west of Wuxu ore field, southern section of the Nandan-Hechi metallogenic belt, is a medium-sized tin–zinc polymetallic deposit. Its genesis has been a matter of debate because of lacking constraints from isotope geology. In this study, LA-MC-ICP-MS U-Pb dating of cassiterite and C-O-S-Pb isotope analyses of monominerals were used to investigate the mineralization age and source of the ore-forming minerals in the Bawang deposit. LA-ICP-MS U–Pb dating of cassiterite yielded ages of 93.1 ± 4.8 Ma and 85.3 ± 6.3 Ma, indicating that the mineralization occurred in the early Late Cretaceous. The δ13CPDB and δ18OSMOW values of calcites at the ore stage range between −0.41‰ and 0.44‰ (average = −11‰) and between 13.8‰ and 15.40‰ (average = 14.59‰), respectively. This shows that ore fluid sources were a mixture of those derived from magma and stratum. Pyrite and sphalerite have uniform δ34S values (−4.45‰~−2.20‰), indicating that sulfur is also derived from the mixing of magmatic hydrothermal and stratum fluids. The Pb isotopic composition of sulfide (206Pb/204Pb = 18.4055~18.7625, 207Pb/204Pb = 15.6745~15.7209, 208Pb/204Pb = 38.6232~39.0370) is consistent with the granite of the same age, indicating that ore-forming metals are mainly derived from magmatic hydrothermal solution. The Bawang deposit is a hydrothermal vein-type deposit in the external contact zone of Late Cretaceous granite, controlled by tectonic fractures, and formed by the interaction of magmatic hydrothermal fluid and carbonate rock. There may be large skarn-type ore bodies in the deep part. The results of this study provide insights into the research and exploration of similar deposits in Nandan-Hechi metallogenic belt and in the Youjiang Basin.

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Zhang, Haowei, Jian Wang, Ahmed Mansour, Jianyong Zhang, Hengye Wei, Xiugen Fu, Lijun Shen, Shaoyun Xiong, Mohamed S. Ahmed, and Thomas Gentzis. "New Age Constraints of the Bilong Co Oil Shale in the Qiangtang Basin, Northern Tibet: Evidence from In Situ U–Pb Dating and Palaeontology." Minerals 14, no. 3 (February 28, 2024): 246. http://dx.doi.org/10.3390/min14030246.

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The Bilong Co oil shale is one of the most significant source rocks in the Mesozoic Qiangtang Basin (Northern Tibet); however, its absolute chronology remains controversial. In this study, in situ carbonate U–Pb isotope dating analysis was carried out for the first time. Detailed field geological investigations yielded some age-diagnostic ammonites, enabling a re-evaluation of the stratigraphic age of the Bilong Co oil shale. A total of 61 spots of U–Pb isotope dating from the middle part of the Bilong Co oil shale section suggests an average age of 181 ± 13 Ma. Elemental geochemistry and diagenetic analysis indicate that the proposed age represents the early deposition of the calcite, and the oil shale was deposited during the Early Jurassic time. This estimated age is further supported by the newly discovered ammonite assemblage of Hildoceratidae–Tiltoniceras sp. at the top part of the oil shale section, which confirms the deposition of the oil shale during the Toarcian age of the late Early Jurassic. Consequently, the Bilong Co oil shale can be assigned to the Quse Formation, which is attributed to the Lower Jurassic rather than the Middle Jurassic. The re-assessment of the stratigraphic age of the Bilong Co oil shale is of great significance for regional evaluation and exploration activities of hydrocarbon source rock layers in the Qiangtang Basin as well as for global stratigraphic correlation of the late Early Jurassic Toarcian oceanic anoxic event.

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Rochelle-Bates, N., N. M. W. Roberts, I. Sharp, U. Freitag, K. Verwer, A. Halton, E. Fiordalisi, et al. "Geochronology of volcanically associated hydrocarbon charge in the pre-salt carbonates of the Namibe Basin, Angola." Geology 49, no. 3 (November 20, 2020): 335–40. http://dx.doi.org/10.1130/g48019.1.

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Abstract In volcanic rifted margins, the timing of hydrocarbon charge is difficult to predict, but is important in understanding fluid genesis. We investigated whether igneous activity was linked to hydrocarbon charge in the prolific South Atlantic pre-salt petroleum system. To do this, we applied in situ carbonate U-Pb geochronology, a relatively novel tool for dating hydrocarbon migration, to bituminous veins in pre-salt travertines from the rifted onshore Namibe Basin (Angola). To test if fluid flow was synchronous with known volcanic pulses, we also obtained new 40Ar/39Ar geochronology from a nearby volcanic complex. Bitumen is associated with calcite in a first generation of veins and vugs, and with dolomite in younger veins. The dated calcite veins yielded a pooled U-Pb age of 86.2 ± 2.4 Ma, which overlaps the volcanism 40Ar/39Ar age of 89.9 ± 1.8 Ma. The overlapping dates and the localized bitumen occurrence around the dated volcanic center show a clear genetic relationship between Late Cretaceous igneous activity and hydrocarbon charge. The dolomite was dated at 56.8 ± 4.8 Ma, revealing a previously unknown Paleocene/Eocene fluid-flow phase in the basin.

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Jiang, Yong. "Middle-Late Jurassic chronology and source-to-sink system of the Sikeshu section in the southern margin of the Junggar Basin, Xinjiang." Advances in Engineering Technology Research 3, no. 1 (November 8, 2022): 133. http://dx.doi.org/10.56028/aetr.3.1.133.

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With the improvement of isotopic testing technology, high-precision dating methods such as SHRIMP or LA-ICP-MS of detrital zircon have been used to analyze and infer the formation age of sedimentary basins, the source of detrital materials, and the tectonic background of the formation and widely used. The LA-ICP-MS zircon U-Pb dating method was used to study the detrital zircon in the Middle-Late Jurassic sandstone in the Sikeshu section of the southern margin of the Junggar Basin, Xinjiang. The results show that the detrital zircon ages are mainly 270~447Ma,240~440Ma,245~432Ma, and 286~360Ma. There are also several ancient zircon ages, mainly 945~1080Ma. Combined with zircon mineralogical characteristics, CL images, Th/U ratio, sandstone petrographic characteristics, and regional chronological data, the primary provenance of the Middle-Late Jurassic sandstone is mainly from the Yilinghabilga Mountains in the North Tianshan, and Carboniferous-Permian volcanic rocks, pyroclastic rocks and Carboniferous granites exposed in the Borokonu Mountains of the Central Tianshan Mountains. By comparing the age changes between the four sampling points, the change process of the North Tianshan-Middle Tianshan source-sink system is obtained. From west to east, the upper Devonian glutamate, the Middle Devonian carbonate, and the large granite bodies of the Carboniferous series constituted the early watershed. From the middle to late period of the Toutunhe Formation to the Xishanyao Formation, from east to west, the Cambrian and Silurian carbonate rocks and the large granites and other rocks formed the late water line.

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Pomiès, C., B. Hamelin, J. Lancelot, and R. Blomqvist. "207 Pb/ 206 Pb and 238 U/ 230 Th dating of uranium migration in carbonate fractures from the Palmottu uranium ore (southern Finland)." Applied Geochemistry 19, no. 3 (March 2004): 273–88. http://dx.doi.org/10.1016/s0883-2927(03)00134-3.

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Piccione, Gavin, E. Troy Rasbury, Brent A. Elliott, J. Richard Kyle, Steven J. Jaret, Alvin S. Acerbo, Antonio Lanzirotti, Paul Northrup, Kathleen Wooton, and Randall R. Parrish. "Vein fluorite U-Pb dating demonstrates post–6.2 Ma rare-earth element mobilization associated with Rio Grande rifting." Geosphere 15, no. 6 (November 8, 2019): 1958–72. http://dx.doi.org/10.1130/ges02139.1.

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Abstract Numerous studies have documented rare-earth element (REE) mobility in hydrothermal and metamorphic fluids, but the processes and timing of REE mobility are rarely well constrained. The Round Top laccolith in the Trans-Pecos magmatic province of west Texas, a REE ore prospect, has crosscutting fractures filled with fluorite and calcite along with a variety of unusual minerals. Most notably among these is an yttrium and heavy rare-earth element (YHREE) carbonate mineral, which is hypothesized to be lokkaite based on elemental analyses. While the Round Top laccolith is dated to 36.2 ± 0.6 Ma based on K/Ar in biotite, U-Pb fluorite and nacrite ages presented here clearly show the mineralization in these veins is younger than 6.2 ± 0.4 Ma (the age of the oldest fluorite). This discrepancy in dates suggests that fluids interacted with the laccolith to mobilize REE more than 30 m.y. after igneous emplacement. The timing of observed REE mobilization overlaps with Rio Grande rift extension, and we suggest that F-bearing fluids associated with extension may be responsible for initial mobilization. A later generation of fluids was able to dissolve fluorite, and we hypothesize this later history involved sulfuric acid. Synchrotron spectroscopy and laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) U-Pb dating of minerals that record these fluids offer tremendous potential for a more fundamental understanding of processes that are important not only for REE but other ore deposits as well.

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Godeau, Nicolas, Pierre Deschamps, Abel Guihou, Philippe Leonide, Anthony Tendil, Axel Gerdes, Bruno Hamelin, and Jean-Pierre Girard. "U-Pb dating of calcite cement and diagenetic history in microporous carbonate reservoirs: Case of the Urgonian Limestone, France." Geology 46, no. 3 (January 24, 2018): 247–50. http://dx.doi.org/10.1130/g39905.1.

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32

Guillong, Marcel, Jörn-Frederik Wotzlaw, Nathan Looser, and Oscar Laurent. "Evaluating the reliability of U–Pb laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) carbonate geochronology: matrix issues and a potential calcite validation reference material." Geochronology 2, no. 1 (June 30, 2020): 155–67. http://dx.doi.org/10.5194/gchron-2-155-2020.

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Abstract. We document that the reliability of carbonate U–Pb dating by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is improved by matching the aspect ratio of the LA single-hole drilling craters and propagating long-term excess variance and systematic uncertainties. We investigated the impact of different matrices and ablation crater geometries using U–Pb isotope analyses of one primary (WC-1) and two secondary reference materials (RMs). Validation RMs (VRMs) include a previously characterised one (ASH-15D) and a new candidate (JT), characterised by ID-TIMS (intercept age: 13.797±0.031 Ma) with excellent agreement to pooled LA-ICP-MS measurements (13.75±0.11 | 0.36 Ma), a U concentration of approx. 1 µg g−1 and 238U∕206Pb ratios from 5 to 460, defining the isochron well. Differences in ablation crater depth to diameter ratios (aspect ratio) introduce an offset due to downhole fractionation and/or matrix effects. This effect can be observed either when the crater size between U–Pb RM and the sample changes or when the ablation rate for the sample is different than for the RM. Observed deviations are up to 20 % of the final intercept age depending on the degree of crater geometry mismatch. The long-term excess uncertainty was calculated to be in the range of 2 % (ASH-15D) to 2.5 % (JT), and we recommend propagating this uncertainty into the uncertainty of the final results. Additionally, a systematic offset to the ID-TIMS age of 2 %–3 % was observed for ASH-15D but not for JT. This offset might be due to different ablation rates of ASH-15D compared to the primary RM or remaining matrix effects, even when the aspect ratios chosen are similar.

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Zaccaria, Daria, Noemi Vicentini, Maria Grazia Perna, Gianluigi Rosatelli, Victor V. Sharygin, Emma Humphreys-Williams, Will Brownscombe, and Francesco Stoppa. "Lamprophyre as the Source of Zircon in the Veneto Region, Italy." Minerals 11, no. 10 (September 30, 2021): 1081. http://dx.doi.org/10.3390/min11101081.

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Discrete zircons, up to 9 mm in length, occur in alluvial deposits from the Veneto area. They are likely derived from the disaggregation of lamprophyric rocks belonging to a regional, pervasive dyke-swarm. Zircon and REE phases occur in both alkaline lamprophyres and connate calcite-bearing felsic lithics and their debris in lamprophyre breccia. We present 36 new complete U–Pb and trace element analyses of zircons and associated inclusions. We used a statistical approach on a larger dataset using new and literature data to evaluate the confidence figure to give an estimation of age of zircons. Inclusions suggest a genetic link with an S–CO2–ZrO–BaO–SrO–CaO-rich fluid/melt possibly associated with carbonate-rich alkaline parental magma and a metasomatised mantle source. This paper confirms the importance of calcite–syenite and lamprophyre genetic link and zircon magmatic origin, in contrast with hydrothermal and metamorphic zircons. U–Pb dating by LA-ICP-MS provides time constrains (40.5–48.4 Ma, Lutetian), consistent with the age of the alkaline magmatic event. Trace element data indicate a link to anorogenic magmatism associated with mantle upwelling. Complex zoning is highlighted by cathodoluminescence images. The Veneto zircons are helpful for regional geological information and may have commercial potential as a critical resource for green technologies.

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LIATI, ANTHI, NIKOS SKARPELIS, and GEORGIA PE-PIPER. "Late Miocene magmatic activity in the Attic-Cycladic Belt of the Aegean (Lavrion, SE Attica, Greece): implications for the geodynamic evolution and timing of ore deposition." Geological Magazine 146, no. 5 (July 15, 2009): 732–42. http://dx.doi.org/10.1017/s0016756809006438.

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AbstractNumerous post-metamorphic Miocene granitoids occur in the area of Lavrion, SE Attica, at the western end of the Attic-Cycladic Belt of the Aegean. U–Pb ion microprobe-dating (SHRIMP) of zircon from a granitoid sill in the hanging-wall of a regional detachment fault reveals two distinct ages: (1) 11.93 ± 0.41 Ma, obtained from inherited zircon cores with metamorphic characteristics (homogeneous cathodoluminescence, low Th/U ratios) and granulite-type (round/resorbed) morphology. This age is interpreted as the time of a likely granulite-facies metamorphism of the precursor rock. (2) 8.34 ± 0.20 Ma, obtained by oscillatory zoned zircon domains with cathodoluminescence and Th/U characteristics typical for magmatic origin. This age is interpreted as the crystallization time of the granitoid sills. Although a granulite-facies metamorphic event has not been recognized so far for rocks of the Attic-Cycladic Belt, it seems to be the most plausible hypothesis to explain both the zircon systematics and age results. This hypothesis is consistent with an extensional regime predominating in the Aegean from Late Miocene times onwards. A possible granulite-facies metamorphism can be related to magmatic underplating at the initial stages of extension, setting an upper age of c. 12 Ma for the operation of the detachment fault. The 8.34 ± 0.20 Ma zircon crystallization age is, statistically, marginally different to a previous K–Ar feldspar date of hornblende-bearing dykes (9.4 ± 0.3 Ma) and identical to a 8.27 ± 0.11 Ma K–Ar biotite date of the main granitoid stock in the area, thus being generally consistent with prior age constraints from the region. Operation of the detachment fault in the Lavrion area is therefore bracketed between c. 11.9 Ma and at least 8.3 Ma. This time range is in line with the time of operation of detachment faults suggested previously for the Cycladic islands. Carbonate-hosted replacement-type massive sulphide Pb–Zn–Ag ores are spatially associated with the detachment fault and related extensional structures in the Basal Unit. Therefore, these Pb–Zn–Ag ores probably also formed within the above time span of c. 11.9 to at least 8.3 Ma. U–Pb ion microprobe (SHRIMP) dating of zircon from an orthogneiss within the metaclastic subunit of the Basal Unit in Lavrion yielded a protolith age of 240 ±4 Ma, consistent with ages of Triassic volcanism elsewhere in Greece.

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Feng, Yuexing, Dunyi Liu, Jianxin Zhao, Wenqing Pan, and Ting Cheng. "<italic>In-situ</italic> LA-MC-ICPMS U-Pb dating method for low-uranium carbonate minerals." Chinese Science Bulletin 65, no. 2-3 (December 10, 2019): 150–54. http://dx.doi.org/10.1360/tb-2019-0355.

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Mundil, Roland, Peter Brack, Martin Meier, Hans Rieber, and Felix Oberli. "High resolution UPb dating of Middle Triassic volcaniclastics: Time-scale calibration and verification of tuning parameters for carbonate sedimentation." Earth and Planetary Science Letters 141, no. 1-4 (June 1996): 137–51. http://dx.doi.org/10.1016/0012-821x(96)00057-x.

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Liu, Xin, Nansheng Qiu, and Qianqian Feng. "The thermal history of Permian carbonate strata reconstructed with clumped isotopes and U–Pb dating: Eastern Sichuan Basin, SW China." Marine and Petroleum Geology 163 (May 2024): 106767. http://dx.doi.org/10.1016/j.marpetgeo.2024.106767.

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Henneberg, Mareike, Jolien Linckens, Michael Schramm, Jörg Hammer, Axel Gerdes, and Gernold Zulauf. "Structural evolution of continental and marine Permian rock salt of the North German Basin: constraints from microfabrics, geochemistry and U–Pb ages." International Journal of Earth Sciences 109, no. 7 (August 9, 2020): 2369–87. http://dx.doi.org/10.1007/s00531-020-01905-w.

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Abstract Analyzing the dynamics of microstructural response on natural deformation in rock salt, we present microfabric, EBSD, geochemical and U–Pb data, obtained from Permian salt formations of the Kiel-Honigsee salt wall in Northern Germany. The samples were recovered from deep drillings, which penetrated through an overturned rock salt sequence of both Rotliegend and Zechstein deposits. The bromide concentration in halite indicates a continental and marine origin for the Rotliegend and Zechstein deposits, respectively. Despite intense deformation, relics of early diagenetic fabrics are still preserved. Deformation of the impure Rotliegend rock salt was accommodated by pressure solution and hydrofracturing as is indicated by the microfabrics and bromide concentration in halite. Fractures in siliciclastic domains were filled with fibrous halite and deformed by subgrain rotation recrystallization (SGR). Fluid-rich Zechstein rock salt, on the other hand, was deformed by formation of subgrains and grain boundary migration (GBM). The distribution of mineral phases and fluids had a significant impact on the fabric evolution and on strain localization. U–Pb dating of carbonate phases of the Rotliegend sequence yielded Permian depositional ages and Jurassic to Cretaceous deformation ages, the latter related to diapiric ascent. The combination of results traces a dynamic evolution of the rock fabric inside the diapir structure driven by locally active deformation processes that can be correlated with early stages of halite deposition and diagenesis and syntectonic fabric reorganization related to diapirism in an extensional setting.

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Wang, Mengqi, Jingwen Mao, Huishou Ye, and Hongying Li. "The Age of Hubi Copper (Cobalt) Ore Mineralization in the Zhongtiao Mountain Area, Southern Margin of the Trans-North China Orogen: New Constraints from U-Pb Dating of Rutile and Monazite." Minerals 12, no. 3 (February 25, 2022): 288. http://dx.doi.org/10.3390/min12030288.

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The Hubi copper (cobalt) ore district, one of the largest typical examples of the sediment-hosted stratiform type in the Zhongtiao Mountain area, is located on the southern margin of the Trans-North China Orogen within the North China Craton (NCC) and has a copper reserve of 0.79 Mt. Mineralization is mainly hosted by the Zhongtiao Group, a sequence of metasedimentary rocks deposited from ~2168 Ma to ~2059 Ma. Subsequently, a collisional orogeny (Trans-North China Orogen) occurred at ~1.85 Ga. The absolute age of mineralization has not been well constrained due to the lack of suitable minerals for dating. Rutile and monazite are common accessory minerals and are intergrown with Cu mineralization in Cu-bearing veins in the Hubi-type copper (cobalt) deposits. This study presents the first new LA-ICP-MS U-Pb ages of hydrothermal rutile and monazite for the Tongmugou and Laobaotan copper (cobalt) deposits in the ore district, which yield lower intercept rutile U-Pb ages of 1815 ± 30 Ma (Mean Squared Weighted Deviation, MSWD = 5.0) and 1858 ± 27 Ma (MSWD = 5.2) for Tongmugou and 1876 ± 30 Ma (MSWD = 5.9) for Laobaotan. Monazite crystals separated from Cu-bearing carbonate veins within the orebody of Tongmugou yield a weighted mean 207Pb/206Pb age of 1856 ± 14 Ma (MSWD = 1.9), which is close to that of rutile within error. Mineralogical observations and geochemical characteristics suggest that both monazite and rutile crystallized in the hydrothermal fluid system and are closely related to Cu sulfide mineralization. Therefore, their nearly identical U-Pb isotope age of ca. 1850 Ma directly reflects the timing of metamorphic hydrothermal Cu mineralization. This age is indistinguishable from that of metamorphism during the collisional orogeny (Trans-North China Orogen) that led to the final amalgamation of the Eastern and Western Blocks. According to previous studies, the primary sedimentary mineralization of the Hubi-type copper (cobalt) deposits was synchronous with the deposition of the Zhongtiao Group. From the perspective of mineralization age, both the Congolese–Zambian Copperbelt and the Hubi copper (cobalt) ore district experienced early preorogenic sedimentary diagenetic mineralization and late metamorphic hydrothermal mineralization related to orogenesis, and the Hubi-type copper (cobalt) deposits may also be some of the oldest sediment-hosted stratiform-type deposits in the world. Moreover, this metamorphic hydrothermal Cu mineralization spread throughout the Zhongtiao Mountain area.

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Guo, Qian, Shun Guo, Yueheng Yang, Qian Mao, Jiangyan Yuan, Shitou Wu, Xiaochi Liu, and Kyaing Sein. "Multiple growth of zirconolite in marble (Mogok metamorphic belt, Myanmar): evidence for episodes of fluid metasomatism and Zr–Ti–U mineralization in metacarbonate systems." European Journal of Mineralogy 36, no. 1 (January 5, 2024): 11–29. http://dx.doi.org/10.5194/ejm-36-11-2024.

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Abstract. Fluid infiltration into (meta-)carbonate rocks is an important petrologic process that induces metamorphic decarbonation and potential mineralization of metals or nonmetals. The determination of the infiltration time and the compositional features of reactive fluids is essential to understand the mechanism and process of fluid–rock interactions. Zirconolite (ideal formula: CaZrTi2O7) is an important U-bearing accessory mineral that can develop in metasomatized metacarbonate rocks. In this study, we investigate the occurrence, texture, composition, and chronology of various types of zirconolite from fluid-infiltrated reaction zones in dolomite marbles from the Mogok metamorphic belt, Myanmar. Three types of zirconolite are recognized: (1) the first type (Zrl-I) coexists with metasomatic silicate and oxide minerals (forsterite, spinel, phlogopite) and has a homogeneous composition with high contents of UO2 (21.37 wt %–22.82 wt %) and ThO2 (0.84 wt %–1.99 wt %). (2) The second type (Zrl-II) has textural characteristics similar to those of Zrl-I. However, Zrl-II shows a core–rim zonation with a slightly higher UO2 content in the rims (average of 23.5 ± 0.4 wt % (n=8)) than the cores (average of 22.1 ± 0.3 wt % (n=8)). (3) The third type (Zrl-III) typically occurs as coronas around baddeleyite and coexists with polycrystalline quartz. Zrl-III has obviously lower contents of UO2 (0.88 wt %–5.3 wt %) than those of Zrl-I and Zrl-II. All types of zirconolite have relatively low rare earth element (REE) contents (< 480 µg g−1 for ΣREE). Microtextures and compositions of the three zirconolite types, in combination with in situ zirconolite U–Pb dating using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), reveal episodic fluid infiltration and element mobilization in the dolomite marbles. The first-stage infiltration occurred at ∼ 35 Ma, leading to the formation of Mg-rich silicates and oxides and accessory minerals (Zrl-I, baddeleyite, and geikielite). The reactive fluid was characterized by high contents of Zr, Ti, U, and Th. After that, some Zrl-I grains underwent a local fluid-assisted dissolution–precipitation process, which produced a core–rim zonation (i.e., the Zrl-II type). The final stage of fluid infiltration, recorded by the growth of Zrl-III after baddeleyite, took place at ∼ 19 Ma. The infiltrating fluid of this stage had relatively lower U contents and higher SiO2 activities than the first-stage infiltrating fluid. This study illustrates that zirconolite is a powerful mineral that can record repeated episodes (ranging from 35 to 19 Ma) of fluid influx, metasomatic reactions, and Zr–Ti–U mineralization in (meta-)carbonates. This mineral not only provides key information about the timing of fluid flow but also documents the chemical variation in reactive fluids. Thus, zirconolite is expected to play a more important role in characterizing the fluid–carbonate interaction, orogenic CO2 release, and the transfer and deposition of rare metals.

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Liu, Lijuan, Jeremy P. Richards, Robert A. Creaser, S. Andrew DuFrane, Karlis Muehlenbachs, and Peter B. Larson. "Geology and age of the Morrison porphyry Cu–Au–Mo deposit, Babine Lake area, British Columbia." Canadian Journal of Earth Sciences 53, no. 9 (September 2016): 950–78. http://dx.doi.org/10.1139/cjes-2015-0231.

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The Morrison porphyry Cu–Au–Mo deposit is genetically and spatially related to Eocene plagioclase–hornblende–biotite porphyry intrusions. One porphyry intrusion yielded a U–Pb age of 52.54 ± 1.05 Ma. Mineralization occurs in three stages: (1) vein-type and disseminated chalcopyrite and minor bornite (associated with potassic alteration and gold mineralization); (2) vein-type molybdenite (associated with weak phyllic alteration); and (3) polymetallic sulfide–carbonate veins (dolomite ± quartz–sphalerite–galena–arsenopyrite–chalcopyrite, associated with weak sericite–carbonate alteration). Re–Os dating of molybdenite yielded ages of 52.54 ± 0.22 and 53.06 ± 0.22 Ma, similar to the age of the host porphyry intrusion. Stage 1 vein fluids were predominantly of magmatic origin: Th = 400–526 °C; salinity = 39.8–47.8 wt.% NaCl equiv.; δ18Ofluid = 3.7‰–6.3‰; disseminated chalcopyrite–pyrite δ34SCDT = 0.2‰ and −0.8‰ (CDT, Canyon Diablo Troilite). Stage 2 fluids were a mixture of magmatic and meteoric water: Th = 320–421 °C; salinity = 37.0–43.1 wt.% NaCl equiv.; δ18Ofluid values range from 0.3‰ to 3.4‰; molybdenite and pyrite δ34SCDT = −2.1‰ and −1.2‰. Stage 3 fluids were predominantly of meteoric water origin: Th = 163–218 °C; salinity = 3.1–3.9 wt.% NaCl equiv.; δ18Ofluid = −2.3‰ to 3.9‰ for early vein quartz, and 1.1‰ to 6.1‰ for late vein dolomite; sphalerite and pyrite δ34SCDT = −7.1‰ to −5.6‰. Morrison is interpreted to be a typical porphyry Cu–Au–Mo deposit related to a calc-alkaline to a high-K calc-alkaline diorite to granodiorite intrusive suite, generated in a continental arc in response to early Eocene subduction of the Kula–Farallon plate beneath North America.

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He, Xi-Heng, Xiao-Hua Deng, Leon Bagas, Jing Zhang, Chao Li, and Wen-Dong Zhang. "Geology, geochronology, and fluid inclusion studies of the Xiaorequanzi volcanogenic massive sulphide Cu–Zn deposit in the East Tianshan Terrane, China." Canadian Journal of Earth Sciences 57, no. 12 (December 2020): 1392–410. http://dx.doi.org/10.1139/cjes-2019-0067.

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The Xiaorequanzi Cu–Zn deposit is in the westernmost part of East Tianshan Terrane in northwestern China. The deposit is unique in the region being a volcanogenic massive sulphide (VMS) deposit located near a zone (or belt) containing giant late Paleozoic porphyry Cu deposits. Aiming to better understand the genesis of the mineral deposits in the terrane and their tectonic setting, we report our findings of detailed studies on fluid inclusion microthermometry, Re–Os dating of chalcopyrite from the massive ore, and U–Pb dating of zircons from the host volcanic rocks. There are two sulphide stages with early pyrite succeeded by chalcopyrite–sphalerite, which are hydrothermally overprinted and supergene enriched. The hydrothermal overprinting is characterised by quartz–sulphide veins crossed by carbonate-rich quartz veins. Quartz from the chalcopyrite–sphalerite stage is characterised by primary fluid inclusions containing H2O–NaCl(–CO2) and homogenise at 228–392 °C with a salinity of 2.2–13.3 wt.% NaCl equiv. Secondary fluid inclusions related to the hydrothermal overprinting homogenise at 170–205 °C with a salinity of 2.7–12.1 wt.% NaCl equiv. Fluid inclusions in the quartz–sulphide stage of the hydrothermal overprinting contain H2O–NaCl with homogenisation temperatures of 164–281 °C and salinities in ranging from 2.9 to 12.4 wt.% NaCl equiv. Fluid inclusion in the quartz–calcite stage contain H2O–NaCl with homogenisation temperatures of 122–204 °C with salinities of 1.4–12.4 wt.% NaCl equiv. These characteristics are like those of the secondary fluid inclusions in the VMS mineralisation. Combining these findings with H–O isotopic data from previous studies, we propose that the primary mineralising fluid is magmatic in origin. Tuff hosting the mineralisation yields a SHRIMP U–Pb zircon age of 352 ± 5 Ma, which is interpreted as the age of the tuff, and a porphyritic felsite dyke intruding the tuff yields a SHRIMP U–Pb zircon date of 345 ± 6 Ma, interpreted as the emplacement age of the dyke. Chalcopyrite from the main orebody at Xiaorequanzi yields a Re–Os isochron age of 336 ± 13 Ma with an initial 187Os/188Os ratio of 0.25 ± 0.55 (MSWD = 12). Given that the VMS deposit is a syngenetic deposit, we regard the upper ca. 349 Ma limit of the Re–Os date as the approximate age of the chalcopyrite. The three dates are the same within error, and the upper limit of the Re–Os date of ca. 349 is taken as the age of the volcanic, dyke, and mineralisation. The volcanic rocks around the Xiaorequanzi deposit have been previously classified as calc–alkaline to high-K calc–alkaline enriched in large-ion lithophile elements and depleted in high-field-strength elements, which are characteristics indicative of a forearc setting. It is suggested that VMS mineralisation formed in a forearc setting related to the north-directed subduction of the Palaeo-Kangguer or North Tianshan oceanic plates.

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43

Zheng, Jiang, Long Wen, Yuhui Ge, Gang Zhou, Ya Zhang, Wei Yan, Huan Jiang, Zili Zhang, and Aihua Xi. "U–Pb Dating of Fibrous Dolomite in the Hydrothermal Dolostone of the Dengying Formation, Central Sichuan Basin, and Its Response to Supercontinent Breakup." Minerals 13, no. 10 (October 23, 2023): 1353. http://dx.doi.org/10.3390/min13101353.

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Super-deep drilling in the central Sichuan Basin encountered volcanic rocks of the Suxiong Formation, which are overlain by multiple hydrothermal alterations within the upper section of the Ediacaran Dengying Formation. This provides an excellent research opportunity to understand the pre-Cambrian hydrothermal activity and geological evolution of the western margin of the Yangtze Craton. Observations revealed the development of a series of hydrothermal dolomite aggregates characterized by the presence of brown sphalerite within fractures and pores of the carbonate rock. Microscopically, the dolomite exhibited fibrous columnar crystallization, forming radial bands with a gradual decrease in crystallization intensity from the center to the periphery. Cathodoluminescence analysis revealed the presence of approximately eight dolomite bands within the aggregate. U–Pb dating from the inner to outer bands yielded isotopic ages of 781 ± 12 Ma for the second band, 683 ± 12 Ma for the fifth, 562 ± 12 Ma for the sixth, and 545.4 ± 6.9 Ma for the seventh. The in situ rare earth element (REE) distribution patterns of the 781 and 683 Ma dolomite bands exhibited similarities. They both showed low total REE content (∑REE), with significant fractionation between light and heavy REEs. Additionally, they exhibited negative anomalies in cerium (Ce) and europium (Eu), while heavy REEs were relatively enriched. The dolomite bands at 562 and 545 Ma also exhibited similar REE characteristics, with low ∑REE and weak fractionation between light and heavy REEs. They also displayed distinct negative anomalies in Ce and Eu, indicating similar distribution patterns. These findings suggested that formation of the banded hydrothermal dolostone occurred during different tectonic events, and the presence of heavy REE-enriched hydrothermal fluids suggested a deep-seated origin. This study has provided preliminary evidence that the Dengying Formation, previously considered to be of the Ediacaran age, has undergone multiple episodes of deep-seated fluid infiltration and alteration since the Mesoproterozoic Era. Importantly, these events coincide with the rifting of the Rodinia and Pannotia supercontinents, aligning with their respective timeframes. This finding raises questions regarding the stratigraphic division and correlation of the formations in the deeply buried core area of the basin.

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Salih, Namam, Howri Mansurbeg, Philippe Muchez, Axel Gerdes, and Alain Préat. "Hydrothermal Fluids and Cold Meteoric Waters along Tectonic-Controlled Open Spaces in Upper Cretaceous Carbonate Rocks, NE-Iraq: Scanning Data from In Situ U-Pb Geochronology and Microthermometry." Water 13, no. 24 (December 13, 2021): 3559. http://dx.doi.org/10.3390/w13243559.

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The Upper Cretaceous carbonates along the Zagros thrust-fold belt “Harir-Safin anticlines” experienced extensive hot brine fluids that produced several phases of hydrothermal cements, including saddle dolomites. Detailed fluid inclusion microthermometry data show that saddle dolomites precipitated from hydrothermal (83–160 °C) and saline fluids (up to 25 eq. wt.% NaCl; i.e., seven times higher than the seawater salinity). The fluids interacted with brine/rocks during their circulation before invading the Upper Cretaceous carbonates. Two entrapment episodes (early and late) of FIs from the hydrothermal “HT” cements are recognized. The early episode is linked to fault-related fractures and was contemporaneous with the precipitation of the HT cements. The fluid inclusions leaked and were refilled during a later diagenetic phase. The late episode is consistent with low saline fluids (0.18 and 2.57 eq. wt.% NaCl) which had a meteoric origin. Utilizing the laser ablation U-Pb age dating method, two numerical absolute ages of ~70 Ma and 3.8 Ma are identified from calcrete levels in the Upper Cretaceous carbonates. These two ages obtained in the same level of calcrete indicate that this unit was twice exposed to subaerial conditions. The earlier exposure was associated with alveolar and other diagenetic features, such as dissolution, micritization, cementation, while the second calcrete level is associated with laminae, pisolitic, and microstromatolite features which formed during the regional uplifting of the area in Pliocene times. In conclusion, the hydrothermal-saddle dolomites were precipitated from high temperature saline fluids, while calcrete levels entrapped large monophase with very low salinity fluid inclusions, indicative for a low temperature precipitation from water with a meteoric origin.

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Sun, Yong-gang, Bi-le Li, Qing-feng Ding, Yuan Qu, Cheng-ku Wang, Lin-lin Wang, and Qing-lin Xu. "Mineralization Age and Hydrothermal Evolution of the Fukeshan Cu (Mo) Deposit in the Northern Great Xing’an Range, Northeast China: Evidence from Fluid Inclusions, H–O–S–Pb Isotopes, and Re–Os Geochronology." Minerals 10, no. 7 (June 30, 2020): 591. http://dx.doi.org/10.3390/min10070591.

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The Fukeshan Cu (Mo) deposit is a newfound porphyry deposit in the northern Great Xing’an Range (GXR), northeast China. In this paper, we present results of chalcopyrite Re–Os geochronology, microthermometry of the fluid inclusions (FIs), and isotopic (H–O–S–Pb) compositions of the Fukeshan Cu (Mo) deposit. Its ore-forming process can be divided into sulfide-barren quartz veins (A vein; stage I), quartz + chalcopyrite + pyrite veins (B vein; stage II), quartz + polymetallic sulfide veins (D vein; stage III), and barren quartz + carbonate ± pyrite veins (E vein; stage IV), with Cu mineralization mainly occurred in stage II. Three types of FIs are identified in this deposit: liquid-rich two-phase (L-type) FIs, vapor-rich two-phase (V-type) FIs, daughter mineral-bearing three-phase (S-type) FIs. The homogenization temperatures of primary FIs hosted in quartz of stages I–IV are 381–494 °C, 282–398 °C, 233–340 °C, and 144–239 °C, with salinities of 7.2–58.6, 4.8–9.9, 1.4–7.9, and 0.9–3.9 wt. % NaCl equivalent, respectively. FIs microthermometry and H–O isotope data suggest that the ore-forming fluids were magmatic in origin and were gradually mixed with meteoric water from stages II to IV. Sulfur and lead isotope results indicate that the ore-forming materials of the Fukeshan Cu (Mo) deposit were likely to have originated from Late Jurassic intrusive rocks. The available data suggest that fluid cooling and incursions of meteoric water into the magmatic fluids were two important factors for Cu precipitation in the Fukeshan Cu (Mo) deposit. Chalcopyrite Re–Os dating yielded an isochron age of 144.7 ± 5.4 Ma, which is similar to the zircon U–Pb age of the quartz diorite porphyry, indicating that Late Jurassic quartz diorite porphyry and Cu mineralization occurred contemporaneously.

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Park, Adrian F., Steven J. Hinds, Christopher R. M. McFarlane, Brandan Boucher, Matthew R. Stimson, and Perry Clark. "Petrography, geochemistry, age, and stratigraphic significance of the Mississippian Boyd Creek tuff, southern New Brunswick, Canada." Atlantic Geoscience 60 (March 6, 2024): 015–35. http://dx.doi.org/10.4138/atlgeo.2024.002.

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The Boyd Creek tuff consists of two pyroclastic flow deposits and more widespread air-fall tuff within a Mississippian red bed sequence located in outcrop and boreholes around Weldon and Pre d’en Haut, Albert and Westmorland counties, New Brunswick. Long recognized as an important stratigraphic marker, it has been placed in either the Tournaisian Weldon Formation or Visean Hillsborough Formation by previous workers, with a position in the upper Tournaisian Weldon Formation being the most recent interpretation. A Visean laser ablation-inductively coupled plasma-mass spectrometry U–Pb zircon age of 336.9 ± 2.0 Ma is consistent with the interpretation that the tuff is part of the Windsor Group and within a fine-grained red and grey sequence of the Hillsborough Formation. Although the tuff is altered and contains abundant xenoliths and xenocrysts, petrography and chemistry are consistent with rhyolite or dacite composition. Its composition and age suggest that the Boyd Creek tuff is one of several volcanic units interpreted to be in the Windsor Group or its temporal equivalents, including rhyolite-trachyte lavas of Cumberland Hill (Cumberland Hill Formation, Mabou Group), tuff in carbonate-evaporite sequence at the Picadilly Mine (Penobsquis), and the red bed Shin Formation (Mabou Group) at Hurley Creek near Minto. Locating and dating other ‘ash beds’ in the Windsor Group offers a way to resolve long-standing issues of correlation in the Visean of New Brunswick and Nova Scotia.

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Milton, Jack E., Kenneth A. Hickey, Sarah A. Gleeson, Hendrik Falck, and Julien Allaz. "In Situ Monazite Dating of Sediment-Hosted Stratiform Copper Mineralization in the Redstone Copper Belt, Northwest Territories, Canada: Cupriferous Fluid Flow Late in the Evolution of a Neoproterozoic Sedimentary Basin." Economic Geology 112, no. 7 (November 1, 2017): 1773–806. http://dx.doi.org/10.5382/econgeo.2017.4529.

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Abstract The 300-km-long Redstone copper belt in the Mackenzie Mountains, Northwest Territories, Canada, is composed of a series of sediment-hosted stratiform copper (SSC) deposits hosted in Neoproterozoic fault-bounded intracontinental rift basins. Mineralization at Coates Lake, the largest of these deposits, is concentrated within microbial laminite layers in the transition zone between underlying continental red beds of the Redstone River Formation and overlying marine carbonates of the Coppercap Formation. Disseminated cupriferous sulfides (chalcopyrite, bornite, and chalcocite) form part of a late diagenetic mineral association with dolomite, K-feldspar, albite, quartz, monazite, apatite, and pyrite that partially replaced detrital and early diagenetic minerals, including calcite cements, sulfate, and earlier generations of pyrite. Bornite (± minor chalcopyrite), calcite, dolomite, quartz, K-feldspar, and albite were also deposited in rare bedding-parallel veins adjacent to the lowermost mineralized microbial laminite layer in the transition zone. The absolute timing of mineralization was constrained by in situ U-Th-Pb chemical dating of monazite from four samples hosting disseminated SSC-type mineralization. The monazite have rounded, Th-U-heavy rare earth element-rich, detrital cores surrounded by Th-U-poor, light rare earth element-S-Sr-rich rims. The rim stage of monazite growth is intergrown with and enveloped by cupriferous sulfide and is paragenetically constrained as being part of the disseminated SSC-type mineralizing event. Eleven detrital cores yielded dates between 1843 and 1025 Ma, older than the depositional age of transition zone strata previously constrained to be between 775 and 732 Ma. Ten monazite rims yielded dates between 661 and 607 Ma. A weighted average date of 635 ± 13 Ma provides a maximum estimate, and is our preferred interpretation, for the absolute age of all copper mineralization at the Coates Lake deposit. Mineralization formed approximately 100 m.y. after deposition of the host rocks, during the thermal sag phase of continental rifting. Stratigraphic reconstructions, coupled with estimates of sediment compaction, indicate that at 635 Ma the transition zone was buried by ~4 km of sediments and overlaid another ~1.7 km of sediments that formed the Redstone River and Thundercloud Formations. Mudstone and carbonate-rich units above the transition zone acted as low permeability caps that led to suprahydrostatic fluid pressures in the underlying sediments. The bedding-parallel veins indicate transient supralithostatic fluid pressures. Free convection of pore fluids began within the transition zone and underlying units once they became hydrologically isolated from overlying strata. Mineralization formed as oxidized saline pore fluids circulated through the red beds (± underlying basaltic flows and basal sedimentary detritus), stripping copper and carrying it up into the transition zone. The salinity of the pore fluids may have, at least in part, originated from cryogenic brines generated by the Sturtian (717–662 Ma) global glaciation event.

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Mundil, Roland, Peter Brack, Martin Meier, Hans Rieber, and Felix Oberli. "Erratum to “High resolution UPb dating of Middle Triassic volcaniclastics: Time-scale calibration and verification for tuning parameters for carbonate sedimentation” [Earth Planet. Sci. Lett. 141 (1996) 137–151]." Earth and Planetary Science Letters 143, no. 1-4 (September 1996): 275. http://dx.doi.org/10.1016/0012-821x(96)00147-1.

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Hao, SONG, XU ZhengQi, SONG ShiWei, NI ShiJun, ZHANG ChengJiang, YAN WenQuan, CHENG FaGui, and LI YaPing. "Geochemistry and LA-ICP-MS zircon U-Pb geochronological dating of diabase dykes and their relationship with mineralization of the carbonate-siliceous-pelitic rock type uranium deposits in Daxin-Qinjia, western Guangxi." Acta Petrologica Sinica 35, no. 9 (2019): 2845–63. http://dx.doi.org/10.18654/1000-0569/2019.09.15.

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Cruset, David, Jaume Vergés, Nuno Rodrigues, Jorge Belenguer, Enric Pascual-Cebrian, Ylènia Almar, Irene Pérez-Cáceres, et al. "U–Pb dating of carbonate veins constraining timing of beef growth and oil generation within Vaca Muerta Formation and compression history in the Neuquén Basin along the Andean fold and thrust belt." Marine and Petroleum Geology 132 (October 2021): 105204. http://dx.doi.org/10.1016/j.marpetgeo.2021.105204.

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Journal articles on the topic 'Carbonate U-Pb dating'

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