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Showing 1 to 14 of 14 for “"Radiometric dating"”.
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The Paleolimnology of Irondequoit Bay: Trophic History Inferred from Sedimentary Diatom Assemblages
… test. These tests include diatom analysis, radiometric dating and sediment chemistry. Using these three tests the author was able to determine the condition of diatoms, the time period tested, and the water quality respectively. The research suggests that the diversity of diatoms found …
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Geochemical investigations of the late early Cambrian extinctions
… by the CIEs. However, uncertainties in radiometric dating of the LIP and the regional variations of the CIEs make it difficult to establish a causal relationship. In this study, we conducted a multi-proxy geochemical analysis of the Shady Dolomite Formation in southwestern Virginia, USA, …
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Applied Geochemistry, Geochronology and Biostratigraphy: Case Studies from the 38th Parallel Structures in Missouri and Orange Basin, Offshore Western South Africa
… and particulate organic matter) and radiometric dating of impact spherules were used to constrain age and a relationship between these enigmatic structures and infer their paleoenvironmental conditions. Novel melting damages, unique to impact, were documented in the palynomorphs in …
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Mafic volcanism in the Colorado Plateau/Basin-and-Range Transition Zone, Hurricane, Utah
… of vesicular basalt, bombs and agglutinate. Radiometric dating and geologic relationships demonstrate that the HVF formed over a period of at least 100,000 years. In the upper crust, magma probably rose along joints in sedimentary rocks because chains of volcanic vents follow joint …
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Arsenic mobility in a changing northern climate: Implications for geochemical baselines and long-term stability of contaminants in lake systems
… organic matter (OM) type and quantity), and radiometric dating (14C and 210Pb) to determine the influence of past and present climate warming on the long-term stability of As in lakes surrounding Tundra Mine. The findings of this study demonstrate baseline As concentrations in lake sediments …
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The Middle Fork Plutonic Complex: a plutonic association of coeval peralkaline and metaluminous magmas in the north-central Alaska Range
… - biotite granite (HB granite). K-Ar and Rb-Sr radiometric dating of rock types shows that they are coeval. Their close spatial and temporal relationships led to complex magmatic interactions. Calculated initial ⁸⁷Sr/⁸⁶Sr for gabbro and diorite group around 0.705 to 0.706. HB granites are …
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Shearing on the Great Glen Fault: Kinematic and Microstructural Evidence Preserved at Different Crustal Levels
… on the GGF by 425 Ma. Strike-slip offset post-dating overlying Devonian sedimentary basins is likely only a few tens of kilometers, requiring substantial (100s of kms) Silurian-aged strike-slip movement on the GGF in most plate reconstruction models for the Caledonian mountain belt, now exposed …
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Late Holocene Logistical and Residential Settlement in Interior Santa Rosa Island, California: A Comparative Analysis of Four Rockshelter Sites
… each hypothesis, I use four lines of evidence: radiometric dating (radiocarbon), faunal analysis (primarily marine fauna), stable isotopic data from Mytilus californianus shell, and geospatial analysis (Euclidian distance and Hot Spot analysis). The first hypothesis is that during the late …
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An investigation of the tufa deposits at Ga-Mohana Hill in the Northern Cape, South Africa: palaeoenvironmental context for Late pleistocene and holocene human occupation in the Southern Kalahari
… springs and streams. They are amenable to radiometric dating, and conditions during their formation can be investigated through geochemical proxies, such as carbon and oxygen isotopes. In this study, I use the tufa deposits at Ga-Mohana Hill, and their association with the archaeological …
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Benthic foraminiferal change and depositional history across the Cretaceous – Paleogene (K/Pg) boundary in the Brazos River area, Texas
… in some sections. Geochemical analysis and radiometric dating have confirmed these as volcanic ashes, with extracted zircons giving a date of 65.95+0.04 Ma. These ash bands are located in Maastrichtian mudstones just below the K/Pg boundary and the recorded date is, within error, that of the …
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The late holocene evolution of coastal wetlands in Argyll, Western Scotland
… may have influenced the reliability of the radiometric dating methods. Marsh sediment geochemistry also serves as a useful proxy for identifying compositional variability over the period of marsh development investigated. Dating of the Argyll saltmarsh cores indicates that over the period …
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EVOLUTION OF THE EASTERN ALPS FROM THE PALEOZOIC ONWARD: CONSTRAINTS AND INSIGHTS FROM THE (ULTRA)BASIC ECLOGITIC COMPLEX OF MILCHENKAR ÖTZTAL-STUBAI COMPLEX (EASTERN ALPS, TYROL, AUSTRIA)
… existence of an eclogitic event in the OSC pre-dating the widespread anatectic plutonism of Ordovician age. This would be consistent with a protracted active margin scenario for the Proto-Alpine Cadomian terranes (e.g., von Raumer et al., 2013) in those times, also supported by …
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INNOVATIVE AND CONVENTIONAL APPROACHES TO DETRITAL ZIRCON PROVENANCE ANALYSIS: LOOKING TO THE PAST, PRESENT, AND FUTURE
… lattice while excluding Pb, making it ideal for radiometric dating. Inexpensive and time-efficient U/Pb age acquisition techniques make zircon the mineral of choice for a majority of provenance studies. </p> <p>The sedimentary basins between the Yangtze River and Red River have long been used to …
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Quantifying crystalline exhumation in the Himalaya
… stage and thus a stacking of Indian Plate units. Radiometric dating of zircon, titanite and rutile by U-Pb and amphibole and micas by Ar-Ar reveal peak pressure conditions at 47-48 Ma. With a maximum exhumation rate of 14 cm/a these rocks reached the crust-mantle boundary at 40-35 km within 1 Ma. …