Готові списки джерел за темами / U-Pb CA-TIMS

Добірка наукової літератури з теми "U-Pb CA-TIMS"

Автор: Grafiati

Опубліковано: 10 грудня 2022

Оновлено: 28 січня 2023

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Статті в журналах з теми "U-Pb CA-TIMS"

Peterman, Emily M., James M. Mattinson, and Bradley R. Hacker. "Multi-step TIMS and CA-TIMS monazite U–Pb geochronology." Chemical Geology 312-313 (June 2012): 58–73. http://dx.doi.org/10.1016/j.chemgeo.2012.04.006.

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Magee Jr., Charles W., Simon Bodorkos, Christopher J. Lewis, James L. Crowley, Corey J. Wall, and Richard M. Friedman. "Examination of the accuracy of SHRIMP U–Pb geochronology based on samples dated by both SHRIMP and CA-TIMS." Geochronology 5, no. 1 (January 11, 2023): 1–19. http://dx.doi.org/10.5194/gchron-5-1-2023.

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Abstract. Estimations of the reproducibility of U–Pb ages from SHRIMP (Sensitive High-Resolution Ion MicroProbe) instruments are based on data from studies that are nearly 2 decades old. Since that time, refinement of analytical procedures and operational improvements have reduced the historically identified uncertainties of SHRIMP U–Pb analysis. This paper investigates 36 SHRIMP thermal ionisation mass spectrometry (TIMS) double-dated “real-world” geologic samples from a variety of igneous rock types to better understand both geological and analytical sources of disagreement between the two dating methods. Geoscience Australia's (GA) use of high-precision chemical abrasion thermal ionisation mass spectrometry (CA-TIMS) for chronostratigraphy in Australian sedimentary basins has produced a substantial selection of precisely dated zircons, which we can use to cross-correlate the SHRIMP and CA-TIMS ages throughout the Phanerozoic. A total of 33 of the 36 ages were reported with external SHRIMP uncertainties less than 1 % (95 % confidence). Six of eight cases where the CA-TIMS age was outside the SHRIMP uncertainty envelope were in samples where the 95 % confidence interval of the reported SHRIMP age was below 0.66 % uncertainty, suggesting that SHRIMP analyses of untreated zircon with smaller uncertainties are probably overoptimistic. The mean age offset between SHRIMP and TIMS ages is 0.095 %, but the distribution appears bimodal. Geological explanations for age discrepancies between SHRIMP and CA-TIMS are suggested by considering intrusive and extrusive age results separately. All but one sample where the SHRIMP age is more than 0.25 % older are volcanic. This offset could be explained by the better single-grain age resolution of TIMS, allowing identification and exclusion of antecrysts from the eruptive population, while SHRIMP does not have a sufficient single-grain precision to deconvolve these populations – leading to an apparent older SHRIMP age. In contrast, SHRIMP ages from plutonic rocks – particularly plutonic rocks from the early Paleozoic – are typically younger than the CA-TIMS ages from the same samples, most likely reflecting Pb loss from non-chemically abraded SHRIMP zircons, while chemical abrasion of zircons prior to TIMS analysis destroyed or corrected these areas of Pb loss.

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von Quadt, A., D. Gallhofer, M. Guillong, I. Peytcheva, M. Waelle, and S. Sakata. "U–Pb dating of CA/non-CA treated zircons obtained by LA-ICP-MS and CA-TIMS techniques: impact for their geological interpretation." J. Anal. At. Spectrom. 29, no. 9 (2014): 1618–29. http://dx.doi.org/10.1039/c4ja00102h.

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Chemical Abrasion Isotope-Dilution Thermal Ionization Mass Spectrometry (CA-ID-TIMS) is known as a high precision technique for resolving lead loss and improving the interpretation of U–Pb zircon age data.

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Herriott, Trystan M., James L. Crowley, Mark D. Schmitz, Marwan A. Wartes, and Robert J. Gillis. "Exploring the law of detrital zircon: LA-ICP-MS and CA-TIMS geochronology of Jurassic forearc strata, Cook Inlet, Alaska, USA." Geology 47, no. 11 (September 23, 2019): 1044–48. http://dx.doi.org/10.1130/g46312.1.

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Abstract Uranium-lead (U-Pb) geochronology studies commonly employ the law of detrital zircon: A sedimentary rock cannot be older than its youngest zircon. This premise permits maximum depositional ages (MDAs) to be applied in chronostratigraphy, but geochronologic dates are complicated by uncertainty. We conducted laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) and chemical abrasion–thermal ionization mass spectrometry (CA-TIMS) of detrital zircon in forearc strata of southern Alaska (USA) to assess the accuracy of several MDA approaches. Six samples from Middle–Upper Jurassic units are generally replete with youthful zircon and underwent three rounds of analysis: (1) LA-ICP-MS of ∼115 grains, with one date per zircon; (2) LA-ICP-MS of the ∼15 youngest grains identified in round 1, acquiring two additional dates per zircon; and (3) CA-TIMS of the ∼5 youngest grains identified by LA-ICP-MS. The youngest single-grain LA-ICP-MS dates are all younger than—and rarely overlap at 2σ uncertainty with—the CA-TIMS MDAs. The youngest kernel density estimation modes are typically several million years older than the CA-TIMS MDAs. Weighted means of round 1 dates that define the youngest statistical populations yield the best coincidence with CA-TIMS MDAs. CA-TIMS dating of the youngest zircon identified by LA-ICP-MS is indispensable for critical MDA applications, eliminating laser-induced matrix effects, mitigating and evaluating Pb loss, and resolving complexities of interpreting lower-precision, normally distributed LA-ICP-MS dates. Finally, numerous CA-TIMS MDAs in this study are younger than Bathonian(?)–Callovian and Oxfordian faunal correlations suggest, highlighting the need for additional radioisotopic constraints—including CA-TIMS MDAs—for the Middle–Late Jurassic geologic time scale.

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Ivanova, A. A., E. B. Salnikova, A. B. Kotov, L. F. Syritso, and Yu V. Plotkina. "U–Pb (CA-ID-TIMS) Geochronological Studies of High-Uranium Metamict Zircons." Doklady Earth Sciences 498, no. 1 (May 2021): 384–87. http://dx.doi.org/10.1134/s1028334x21050068.

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Doughty, P. Ted, and K. R. Chamberlain. "Protolith age and timing of Precambrian magmatic and metamorphic events in the Priest River complex, northern Rockies." Canadian Journal of Earth Sciences 45, no. 1 (January 1, 2008): 99–116. http://dx.doi.org/10.1139/e07-067.

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U–Pb dating of detrital zircons, magmatic zircons, and metamorphic zircon overgrowths and titanites from the Priest River complex, USA, reveal the ages of high-grade metasedimentary rocks, intrusive ages of associated igneous rocks, and the timing of Precambrian metamorphic events. Sensitive high-mass resolution ion microprobe (SHRIMP) U–Pb dates of detrital zircons from the Hauser Lake gneiss and Gold Cup Quartzite are predominately Paleoproterozoic with some Archean grains. The Hauser Lake gneiss contains detrital zircons with nearly concordant ages as young as 1511 Ma. Isotope dilution – thermal ionization mass spectrometry (ID–TIMS) and chemical abrasion – thermal ionization mass spectrometry (CA–TIMS) dating of magmatic zircon from amphibolites in the Hauser Lake Gneiss yield 1470–1430 Ma crystallization ages based on discordant data, with Cretaceous lower intercepts. The U–Pb zircon systematics are very complex and reflect multiple periods of magmatic and metamorphic growth. A combination of mechanical abrasion, chemical abrasion (CA–TIMS), and SHRIMP methods were required to identify the major geochronological components. These data, in addition to one Nd model age, strengthen correlations between the Hauser Lake Gneiss and the lower Belt–Purcell Supergroup and the Gold Cup Quartzite with the Neihart Quartzite, which underlies the Belt–Purcell Supergroup. Four SHRIMP-dated metamorphic zircon overgrowths give concordant Grenville dates with a weighted average of 1127 ± 110 Ma. This Grenville-aged metamorphic event is recorded by many isotopic systems in the Belt–Purcell basin and reflects a static thermal event, possibly driven by magmatism at depth.

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Park, Yuem, Nicholas L. Swanson-Hysell, Scott A. MacLennan, Adam C. Maloof, Mulubrhan Gebreslassie, Marissa M. Tremblay, Blair Schoene, et al. "The lead-up to the Sturtian Snowball Earth: Neoproterozoic chemostratigraphy time-calibrated by the Tambien Group of Ethiopia." GSA Bulletin 132, no. 5-6 (October 17, 2019): 1119–49. http://dx.doi.org/10.1130/b35178.1.

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Abstract The Tonian-Cryogenian Tambien Group of northern Ethiopia is a mixed carbonate-siliciclastic sequence that culminates in glacial deposits associated with the first of the Cryogenian glaciations—the Sturtian “Snowball Earth.” Tambien Group deposition occurred atop arc volcanics and volcaniclastics of the Tsaliet Group. New U-Pb isotope dilution–thermal ionization mass spectrometry (ID-TIMS) dates demonstrate that the transition between the Tsaliet and Tambien Groups occurred at ca. 820 Ma in western exposures and ca. 795 Ma in eastern exposures, which is consistent with west to east arc migration and deposition in an evolving back-arc basin. The presence of intercalated tuffs suitable for high-precision geochronology within the Tambien Group enable temporal constraints on stratigraphic data sets of the interval preceding, and leading into, the Sturtian glaciation. Recently discovered exposures of Sturtian glacial deposits and underlying Tambien Group strata in the Samre Fold-Thrust Belt present the opportunity to further utilize this unique association of tuffs and carbonate lithofacies. U-Pb ID-TIMS ages from zircons indicate that Tambien Group carbonates were deposited from ca. 820 Ma until 0–2 m.y. before the onset of the Sturtian glaciation, making the group host to a relatively complete carbonate stratigraphy leading into this glaciation. New δ13C and 87Sr/86Sr data and U-Pb ID-TIMS ages from the Tambien Group are used in conjunction with previously published isotopic and geochronologic data to construct newly time-calibrated composite Tonian carbon and strontium isotope curves. Tambien Group δ13C data and U-Pb ID-TIMS ages reveal that a pre-Sturtian sharp negative δ13C excursion (referred to as the Islay anomaly in the literature) precedes the Sturtian glaciation by ∼18 m.y., is synchronous in at least two separate basins, and is followed by a prolonged interval of positive δ13C values. The composite Tonian 87Sr/86Sr curve shows that, following an extended interval of low and relatively invariant values, inferred seawater 87Sr/86Sr rose ca. 880–770 Ma, then subsequently decreased leading up to the ca. 717 Ma initiation of the Sturtian glaciation. These data, when combined with a simple global weathering model and analyses of the timing and paleolatitude of large igneous province eruptions and arc accretion events, suggest that the 87Sr/86Sr increase was influenced by increased subaerial weathering of radiogenic lithologies as Rodinia rifted apart at low latitudes. The following 87Sr/86Sr decrease is consistent with enhanced subaerial weathering of arc lithologies accreting in the tropics over tens of millions of years, lowering pCO2 and contributing to the initiation of the Sturtian glaciation.

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Catlos, Elizabeth J., Darren F. Mark, Stephanie Suarez, Michael E. Brookfield, C. Giles Miller, Axel K. Schmitt, Vincent Gallagher, and Anne Kelly. "Late Silurian zircon U–Pb ages from the Ludlow and Downton bone beds, Welsh Basin, UK." Journal of the Geological Society 178, no. 1 (August 14, 2020): jgs2020–107. http://dx.doi.org/10.1144/jgs2020-107.

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The Ludlow Bone Bed (Welsh Basin) is a critical stratigraphic horizon and contains a rich assemblage of fish scales. Units above provide insights into the early evolution of animal and plant life. The bed has not yet been radioisotopically dated. Here, we report 207 secondary ion mass spectrometry (SIMS) ages from 102 zircon (ZrSiO4) grains from the Ludlow (n = 2) and stratigraphically higher Downton (n = 1) bone beds. SIMS ages are middle Ordovician (471.6 ± 20.7 Ma) to late Devonian (375.7 ± 14.6 Ma, 238U–206Pb, ±1σ analytical uncertainty). Cathodoluminescence images show that the youngest ages appear affected by alteration. Chemical abrasion isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS) U–Pb geochronology was utilized to improve precision. Detrital zircon grains from Downton yield 424.91 ± 0.34/0.42/0.63 Ma and from Ludlow 424.85 ± 0.32/0.41/0.62 Ma (n = 5 each, 238U–206Pb, ±2σ analytical, tracer or systematic uncertainty). These ages provide a maximum deposition age. Results overlap the basal Přídolí age (423.0 ± 2.3 Ma) in its stratotype (Požáry Section, Reporyje, Prague, Czech Republic). The Ludlow Bone Bed marks the base of the local Downton Group, which has previously been correlated with the base of the Přídolí Series. The CA-ID-TIMS ages are older than those for other land arthropod-bearing sediments, such as the Cowie Harbour Fish Bed and Rhynie Chert.Supplementary material: An Excel file containing detailed information on the SIMS analyses, a figure showing calibration curves for AS3 standards sputtered over sessions 1 and 2, and a figure showing CA-ID-TIMS U–Pb age data (concordia and weighted mean plots) are available at https://doi.org/10.6084/m9.figshare.c.5087031

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White, Lee F., Kimberly T. Tait, Sandra L. Kamo, Desmond E. Moser, and James R. Darling. "Highly accurate dating of micrometre-scale baddeleyite domains through combined focused ion beam extraction and U–Pb thermal ionization mass spectrometry (FIB-TIMS)." Geochronology 2, no. 2 (July 7, 2020): 177–86. http://dx.doi.org/10.5194/gchron-2-177-2020.

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Abstract. Baddeleyite is a powerful chronometer of mafic magmatic and meteorite impact processes. Precise and accurate U–Pb ages can be determined from single grains by isotope dilution thermal ionization mass spectrometry (ID-TIMS), but this requires disaggregation of the host rock for grain isolation and dissolution. As a result, the technique is rarely applied to precious samples with limited availability (such as lunar, Martian, and asteroidal meteorites and returned samples) or samples containing small baddeleyite grains that cannot readily be isolated by conventional mineral separation techniques. Here, we use focused ion beam (FIB) techniques, utilizing both Xe+ plasma and Ga+ ion sources, to liberate baddeleyite subdomains directly, allowing their extraction for ID-TIMS dating. We have analysed the U–Pb isotope systematics of domains ranging between 200 and 10 µm in length and from 5 to ≤0.1 µg in mass. In total, six domains of Phalaborwa baddeleyite extracted using a Xe+ plasma FIB (pFIB) yield a weighted mean 207Pb∕206Pb age of 2060.1±2.5 Ma (0.12 %; all uncertainties 2σ), within uncertainty of reference values. The smallest extracted domain (ca. 10×15×10 µm) yields an internal 207Pb∕206Pb age uncertainty of ±0.37 %. Comparable control on cutting is achieved using a Ga+-source FIB instrument, though the slower speed of cutting limits potential application to larger grains. While the U–Pb data are between 0.5 % and 13.6 % discordant, the extent of discordance does not correlate with the ratio of material to ion-milled surface area, and results generate an accurate upper-intercept age in U–Pb concordia space of 2060.20±0.91 Ma (0.044 %). Thus, we confirm the natural U–Pb variation and discordance within the Phalaborwa baddeleyite population observed with other geochronological techniques. Our results demonstrate the FIB-TIMS technique to be a powerful tool for highly accurate in situ 207Pb∕206Pb (and potentially U–Pb in concordant materials) age analysis, allowing dating of a wide variety of targets and processes newly accessible to geochronology.

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Tapster, Simon, and Joshua W. G. Bright. "High-precision ID-TIMS cassiterite U–Pb systematics using a low-contamination hydrothermal decomposition: implications for LA-ICP-MS and ore deposit geochronology." Geochronology 2, no. 2 (December 18, 2020): 425–41. http://dx.doi.org/10.5194/gchron-2-425-2020.

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Abstract. Cassiterite (SnO2) is the most common ore phase of Sn. Typically containing 1–100 µg g−1 of uranium and relatively low concentrations of common Pb, cassiterite has been increasingly targeted for U–Pb geochronology, principally via microbeam methods, to understand the timing and durations of granite-related magmatic–hydrothermal systems throughout geological time. However, due to the extreme resistance of cassiterite to most forms of acid digestion, there has been no published method permitting the complete, closed-system decomposition of cassiterite under conditions in which the basic necessities of measurement by isotope dilution can be met, leading to a paucity of reference and validation materials. To address this a new low blank (< 1 pg Pb) method for the complete acid decomposition of cassiterite utilising HBr in the presence of a mixed U–Pb tracer, U and Pb purification, and thermal ionisation mass spectrometry (TIMS) analyses has been developed. Decomposition rates have been experimentally evaluated under a range of conditions. A careful balance of time and temperature is required due to competing effects (e.g. HBr oxidation), yet the decomposition of 500 µm diameter fragments of cassiterite is readily achievable over periods comparable to zircon decomposition. Its acid-resistant nature can be turned into an advantage by leaching common Pb-bearing phases (e.g. sulfides, silicates) without disturbing the U–Pb systematics of the cassiterite lattice. The archetypal Sn–W greisen deposit of Cligga Head, SW England, is used to define accuracy relative to chemical abrasion–isotope dilution–thermal ionisation mass spectrometry (CA-ID-TIMS) zircon U–Pb ages and demonstrates the potential of this new method for resolving high-resolution timescales (<0.1 %) of magmatic–hydrothermal systems. However, data also indicate that the isotopic composition of initial common Pb varies significantly, both between crystals and within a single crystal. This is attributed to significant fluid–rock interactions and the highly F-rich acidic nature of the hydrothermal system. At microbeam precision levels, this issue is largely unresolvable and can result in significant inaccuracy in interpreted ages. The ID-TIMS U–Pb method described herein can, for the first time, be used to properly characterise suitable reference materials for microbeam cassiterite U–Pb analyses, thus improving the accuracy of the U–Pb cassiterite chronometer as a whole.

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Дисертації з теми "U-Pb CA-TIMS"

Cappello, Mariko. "New radiometric age constraints on the Ordovician-Silurian boundary from Anticosti Island (eastern Canada) and the Siljan district (Sweden)." Thesis, 2019. http://hdl.handle.net/1828/11089.

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The transition from the end of the Ordovician to the beginning of the Silurian Period is characterized by the glaciation of the Gondwana paleocontinent, eustatic sea level change, a perturbation to the global carbon cycle and one of the ve major mass extinctions of the Phanerozoic Eon. Due to signi cant sea level fall, the Ordovician-Silurian (O-S) boundary is often marked by hiatus and exposure in the shallow marine geologic record (e.g., Copper et al. [2013]). Two locations that host stratigraphic succession close to the boudary are Anticosti Basin of Quebec (Canada, e.g., Desrochers et al. [2010]), and the carbonate mounds of the Siljan ring district (Dalarna County, Sweden, e.g., Ebbestad et al. [2015]). The exact timing and dynamics of the glaciation and mass extinction are yet to be understood. Similarly, the interplay between those events and the carbon cycle perturbation are still unclear. As a result, there is a serious need for radiometric age constraints in this crucial part of the Paleozoic Era. The acquisition of more radiometric dates, achieved in this study, aims to address the present dearth of absolute dates close to the boundary. The dates produced in this study represent the first modern geochronologic constraints on the O-S boundary, leveraging the development of the EARTHTIME initiative and the latest U-Pb dating techniques that have improved accuracy and allowed for dating of single zircon crystals at <=0.1% precision level. Here I present two new U-Pb zircon ages obtained via bentonite dating. The first bentonite, 443.61+-0.52 Ma (2, including analytical, tracer calibration and decay constant uncertainties) was collected from the base of the Lousy Cove Member, Ellis Bay Formation (Anticosti Island, Quebec, Canada). The second one, 443.28+-0.50 Ma (including analytical, tracer calibration and decay constant uncertainties) comes from a karstic void within the Boda Core Facies of the Boda Formation (Dalarna County, Sweden). U-Pb geochronology (chemical abrasion, isotope dilution, thermal ionization mass spectrometry: CA-ID-TIMS) on single zircons was used to obtain these ages. These results are the closest radiometric ages to the current O-S boundary (compared to any time constraints in the 2012 Geologic Time Scale) and allow to signifcantly reduce the uncertainty of the current age boundary (443.8+-1.5, Cohen et al. [2018]). Furthermore these absolute ages have been used to make models that explore drivers of Earth system change, such as an end-Ordovician global carbon cycle perturbation.
Graduate
2021-07-07

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Wainman, Carmine Christopher. "Controls on the geometry, stratigraphic distribution and quality of coals of Middle to Upper Jurassic strata in eastern Australia." Thesis, 2017. http://hdl.handle.net/2440/122078.

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The Middle to Upper Jurassic Walloon Coal Measures of eastern Australia host petroleum resources mostly in the form of coal bed methane. The coals accumulated at a high-latitude (>75°S) during a greenhouse epoch and occur in regionally extensive fluviolacustrine successions. Previous studies have described the spatial relationship of facies using a variety of (and sometimes ambiguously defined) stratigraphic frameworks. This was complicated by the absence of marker beds or published radiometric dates. The coal beds are thin and laterally discontinuous and their origin, which has been poorly understood, has implications for consistent stratigraphic correlations. Improved correlation techniques and an understanding of the controls on coal bed geometry should allow better prediction of: 1) the location and architecture of prospective reservoirs, and 2) gas drainage patterns around individual wells. This study aims to address these questions by building upon pre-existing notions on the evolution of eastern Australia during the Middle to Late Jurassic using an integrated approach with new sedimentologic and palynologic data, combined with precise U-Pb dating of volcanic sediments and basin subsidence studies. Zircon from twenty-eight tuffs in 12 wells across the Surat and Clarence- Moreton Basins were dated using the high-precision chemical abrasion thermal ionization mass spectrometry (CA-TIMS) technique to within an error margin of ±40 ka. In addition, two volcanogenic sandstones from one well that intersected the Birkhead Formation in the Eromanga Basin were dated using the same methodology to within ±50 ka. On a 1237 km transect, five regional datums <420 ka in duration were defined for a chronostratigraphic framework using UPb dates. The dated zircons indicate that the Walloon Coal Measures that had previously been considered as Middle Jurassic (Aalenian-Callovian) are largely of Upper Jurassic age (Oxfordian-Tithonian). The new dates also reveal the diachroneity of coal-bearing facies across eastern Australia and inconsistencies in the correlation of lithostratigraphic units. Jurassic spore-pollen units of Price (1997) were also calibrated to the geologic time-scale using the same U-Pb dates to enable chronostratigraphic horizons to be correlated between basins where volcanic sediments are absent. The first occurrences of key taxa maybe younger than originally estimated, possibly by as much as ~4.2 Ma. These interpretations require further palynological analyses to confirm the age of first occurrences in wells to due to the rarity of key spore-pollen taxa. A high-resolution investigation on the roles of accommodation creation and climate on coal bed geometry suggest that, although subsidence was important in determining the abundance of coal, the climatic patterns contributed towards their thin, discontinuous character. Although the Walloon Coal Measures were deposited at high latitudes (>75°S), the coals originated from peats that accumulated in mires that experienced a warm temperate climate. Rapid and frequent climate change in the polar region may have limited the window of opportunity for thick, widespread coals to develop. New sedimentological and palynological data from the Surat Basin substantially revises interpretations of the environments of deposition. Sedimentary facies and spore-pollen assemblages confirm deposition in a predominately fluviolacustrine setting. However, the identification of tidally-influenced facies, acritarchs and dinoflagellate cysts (a first for Jurassic-aged strata in the basin) indicate periods of brackish water conditions. Marine incursions may have come from the north and the east during time of high eustatic sea-level during the Jurassic. Palaeogeographic reconstructions over 13 Ma reveal extensive fluviolacustrine systems draining from an eroding orogenic belt into proximal estuarine complexes. Allocyclic controls revealed by incised valleys and the deposition of transgressive estuarine facies strongly suggests the accumulation of coal (peat) was unlikely to be coeval with clastic sedimentation because of frequent changes in base level. This study illustrates that a multidisciplinary approach (notably the acquisition of precise U-Pb dates from volcanic sediments and the recognition of subtle indicators of marine influences) can be used to elucidate complex continental successions over large geographic areas. These type of studies will help in the search for subtle oil and gas reservoirs and better calculation of resource and reserve numbers. They may also be of use in better understanding sedimentary mineral resources and groundwater aquifer systems.
Thesis (Ph.D.) -- University of Adelaide, Australian School of Petroleum, 2018

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Частини книг з теми "U-Pb CA-TIMS"

Hodgin, Eben B., Francis A. Macdonald, Paul Karabinos, James L. Crowley, and Douglas N. Reusch. "A reevaluation of the tectonic history of the Dashwoods terrane using in situ and isotope-dilution U-Pb geochronology, western Newfoundland." In New Developments in the Appalachian-Caledonian- Variscan Orogen. Geological Society of America, 2022. http://dx.doi.org/10.1130/2021.2554(10).

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ABSTRACT Synthesis of the Ordovician Taconic orogeny in the northern Appalachians has been hindered by along-strike variations in Laurentian, Gondwanan, and arc-generated tectonic elements. The Dashwoods terrane in Newfoundland has been interpreted as a peri-Laurentian arc terrane that collided with the Laurentian margin at the onset of the Taconic orogeny, whereas along strike in New England, the More-town terrane marks the leading edge of peri-Gondwanan arcs. The peri-Laurentian affinity of the Dashwoods terrane hinges on the correlation of its oldest metasedimentary rocks with upper Ediacaran to Lower Ordovician rift-drift deposits of the Laurentian Humber margin in western Newfoundland. Here, we report U-Pb dates and trace-element geochemistry on detrital zircons from metasedimentary rocks in the southern Dashwoods terrane that challenge this correlation and provide new insights into the Taconic orogeny. Based on age and trace-element geochemistry of detrital zircons analyzed by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) and chemical abrasion–isotope dilution–thermal ionization mass spectrometry (CA-ID-TIMS), we identified ca. 462–445 Ma sedimentary packages with a mixed provenance consisting of Laurentian, Gondwanan, and arc-derived Cambrian–Ordovician sources. These deposits overlap in age with Upper Ordovician strata of the Badger Group of the Exploits subzone, which also contain Laurentian detritus. We infer dominantly east-directed transport of Laurentian detritus from the Taconic collision zone across a postcollisional arc–back-arc complex at ca. 462–455 Ma followed by dominantly west-directed transport of detritus from the Red Indian Lake arc at ca. 455–445 Ma. Our analysis of zircon inheritance from Dashwoods igneous rocks suggests that 1500–900 Ma Laurentian crystalline basement of the Humber margin is an unlikely source of Dashwoods inherited zircon. Instead, a more cosmopolitan Laurentian inheritance may be best explained as sourced from subducted Laurentian sediment. Our results demonstrate that the sampled metasedimentary units from the southern Dashwoods terrane do not correlate with rift-drift strata of the Humber margin as previously proposed, nor with the basement of the Moretown terrane; yet, these Middle to Upper Ordovician successions suggest the potential for an alternative plate-tectonic model in which the Taconic orogeny may have been initiated by collision of Gondwanan arc terranes that closed the main tract of the Iapetus Ocean along the Baie Verte–Brompton Line.

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Mattinson, James M., and Clifford A. Hopson. "New high-precision CA-TIMS U-Pb zircon plateau ages for the Point Sal and San Simeon ophiolite remnants, California Coast Ranges." In Special Paper 438: Ophiolites, Arcs, and Batholiths: A Tribute to Cliff Hopson, 103–12. Geological Society of America, 2008. http://dx.doi.org/10.1130/2008.2438(02).

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Rabayrol, Fabien, Craig J. R. Hart, Richard M. Friedman, and Richard A. Spikings. "Diachronous Magmatic and Cu-Au-Mo Metallogenic Responses to Slab Roll-Back Initiation from Northwest Anatolia to the Balkans, Western Tethyan Eocene Magmatic Belt." In Tectonomagmatic Influences on Metallogeny and Hydrothermal Ore Deposits: A Tribute to Jeremy P. Richards (Volume I), 17–28. Society of Economic Geologists, 2021. http://dx.doi.org/10.5382/sp.24.02.

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Анотація:

ABSTRACT The Bursa mineral district in northwest Anatolia (Turkey) is an emerging prospective area for porphyry Cu-Mo (Au-Re) mineralization along the Western Tethyan Eocene magmatic belt that links the Balkan to Lesser Caucasus regions along the southern Black Sea coast. Field observations as well as time constraints on mineralized magmas of the Bursa district are limited. Additionally, the tectonic setting of Eocene magmatism in northwest Turkey is controversial and includes either Neotethyan slab roll-back or break-off scenario. We show that the Bursa mineral district consists of porphyry Cu-Mo, skarn Cu, and rare epithermal Au-Ag deposits, prospects, and occurrences on the footwall of the Eskişehir fault, south of the İzmir-Ankara-Erzincan suture zone. The porphyry prospects are hosted within porphyritic dioritic, granodioritic, and granitic rocks that were altered by potassic and phyllic assemblages and quartz-sulfide vein stockwork zones. Our new CA-TIMS and LA-ICP-MS U-Pb and 40Ar/39Ar ages indicate that porphyry mineralization of the Bursa district formed between 51 and 46 Ma and thus before the porphyry and epithermal Cu-Au mineralization of the Biga (~43–39 Ma) and Rhodope districts (~35–31 Ma) and the Serbo-Macedonian belt (~36–22 Ma). Therefore, we interpret that Eocene magmatism and associated Cu-Au-Mo mineralization migrated westward along the western part of the Western Tethyan Eocene magmatic belt. This migration, which is specific to the Eocene period, represents a second-order and diachronous response to the first-order southward magmatic front migration and roll-back initiation of the Hellenic slab beneath the Balkan-Aegean-western Anatolian region since the Late Cretaceous.

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Тези доповідей конференцій з теми "U-Pb CA-TIMS"

Ivanova, Anna, and Ekaterina Salnikova. "U-Pb (CA-ID-TIMS) geochronological studies of the metamict zircons." In Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.5236.

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Thompson, Margaret D., and Jahandar Ramezani. "MID-SILURIAN CAPE ANN PLUTON, NE MASSACHUSETTS: U-PB CA-TIMS GEOCHRONOLOGY AND LINGERING LITHOTECTONIC QUESTIONS." In 51st Annual Northeastern GSA Section Meeting. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016ne-271834.

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Messori, Fabio, Maria Ovtcharova, Johannes Zieger, Gerd Geyer, Ulf Linnemann, Mandy Hofmann, and Patricia Vickers-Rich. "New high precision U-Pb CA-ID-TIMS zircon ages from the Terminal Ediacaran in Namibia." In Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.7132.

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Grosswiler, Kate, and Brian Kelley. "A U-PB CA-ID-TIMS DATE FOR THE WRANGELLIA LARGE IGNEOUS PROVINCE IN THE KLUANE RANGE, YUKON." In GSA Connects 2022 meeting in Denver, Colorado. Geological Society of America, 2022. http://dx.doi.org/10.1130/abs/2022am-383332.

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Tian, Hepeng, Majie Fan, Kevin R. Chamberlain, Lowell Waite, and Robert J. Stern. "ZIRCON LA-ICPMS AND CA-TIMS U-PB DATES OF LATE PALEOZOIC VOLCANIC TUFFS IN THE MIDLAND BASIN, WEST TEXAS." In 54th Annual GSA South-Central Section Meeting 2020. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020sc-343618.

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Griffis, Neil, Roland Mundil, C. Brenhin Keller, Isabel P. Montañez, John L. Isbell, Nicholas D. Fedorchuk, Bastien Linol, Roberto Iannuzzi, Fernando Vesely, and Qing-zhu Yin. "DECIPHERING AGE DISPERSION IN HIGH-RESOLUTION CA-TIMS U-PB ZIRCON ANALYSIS: EXAMPLES FROM THE CARBONIFEROUS-PERMIAN PARANÁ AND KAROO BASINS." In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-305834.

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Memeti, Vali, Melissa Chambers, Michael P. Eddy, and Blair Schoene. "PROTRACTED MAGMATIC K-FELDSPAR MEGACRYST GROWTH REVEALED WITH CA-ID-TIMS-TEA U-PB ZIRCON GEOCHRONOLOGY IN THE TUOLUMNE INTRUSIVE COMPLEX, CALIFORNIA." In GSA Annual Meeting in Phoenix, Arizona, USA - 2019. Geological Society of America, 2019. http://dx.doi.org/10.1130/abs/2019am-340901.

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Eberth, David A., Jahandar Ramezani, Eric M. Roberts, Raymond R. Rogers, Dennis R. Braman, and David C. Evans. "BIOSTRATIGRAPHIC IMPORTANCE OF THE NEW CA-TIMS U-PB GEOCHRONOLOGY FOR THE BELLY RIVER GROUP AT DINOSAUR PROVINCIAL PARK (CAMPANIAN, ALBERTA, CANADA)." In Rocky Mountain Section - 69th Annual Meeting - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017rm-292286.

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Crowley, James L., Mark D. Schmitz, John S. Myers, and Jesse B. Walters. "CA-TIMS U-PB DATES FROM HADEAN ZIRCON FROM THE JACK HILLS, AUSTRALIA: IMPROVING THE ACCURACY OF AGES OF METAMORPHOSED DETRITAL ZIRCON." In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-303687.

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Chan, Christine, Noah M. McLean, Ren A. Thompson, Amy Gilmer, Joseph Andrew, and A. Kate Souders. "TIMESCALES OF MAGMATISM DURING LARGE-SCALE EXTENSION: NEW CA-TIMS U-PB ZIRCON GEOCHRONOLOGY OF LATE-MIOCENE INTRUSIONS, CENTRAL DEATH VALLEY, CALIFORNIA." In GSA Connects 2021 in Portland, Oregon. Geological Society of America, 2021. http://dx.doi.org/10.1130/abs/2021am-367511.

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