Fission track age of Transantarctic Mountain microtektites

The Zhuguangshan complex hosts the main uranium production area in South China. We report (U-Th)/He and fission track thermochronological data from Triassic–Jurassic mineralized and non-mineralized granites and overlying Cambrian and Cretaceous sandstone units from the Lujing uranium ore field (LUOF) to constrain the upper crustal tectono-thermal evolution of the central Zhuguangshan complex. Two Cambrian sandstones yield reproducible zircon (U-Th)/He (ZHe) ages of 133–106 Ma and low effective uranium (eU) content (270–776 ppm). One Upper Cretaceous sandstone and seven Mesozoic granites are characterized by significant variability in ZHe ages (154–83 Ma and 167–36 Ma, respectively), which show a negative relationship with eU content (244–1098 ppm and 402–4615 ppm), suggesting that the observed age dispersion can be attributed to the effect of radiation damage accumulation on 4He diffusion. Correspondence between ZHe ages from sandstones and granites indicates that surrounding sedimentary rocks and igneous intrusions supplied sediment to the Cretaceous–Paleogene Fengzhou Basin lying adjacent to the LUOF. The concordance of apatite fission track (AFT) central ages (61–54 Ma) and unimodal distributions of confined track lengths of five samples from different rock units suggest that both sandstone and granite samples experienced a similar cooling history throughout the entire apatite partial annealing zone (~110–60 °C). Apatite (U-Th-Sm)/He (AHe) ages from six non-mineralized samples range from 67 to 19 Ma, with no apparent correlation to eU content (2–78 ppm). Thermal history modeling of data suggests that the LUOF experienced relatively rapid Early Cretaceous cooling. In most samples, this was followed by the latest Early Cretaceous–Late Cretaceous reheating and subsequent latest Late Cretaceous–Recent cooling to surface temperatures. This history is considered as a response to the transmission of far-field stresses, involving alternating periods of regional compression and extension, related to paleo-Pacific plate subduction and subsequent rollback followed by Late Paleogene–Recent India–Asia collision and associated uplift and eastward extrusion of the Tibetan Plateau. Thermal history models are consistent with the Fengzhou Basin having been significantly more extensive in the Late Cretaceous–Early Paleogene, covering much of the LUOF. Uranium ore bodies which may have formed prior to the Late Cretaceous may have been eroded by as much as ~1.2 to 4.8 km during the latest Late Cretaceous–Recent denudation.

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Tectonic Evolution of the SE West Siberian Basin (Russia): Evidence from Apatite Fission Track Thermochronology of Its Exposed Crystalline Basement

Minerals ◽

10.3390/min11060604 ◽

2021 ◽

Vol 11 (6) ◽

pp. 604

Author(s):

Evgeny V. Vetrov ◽

Johan De Grave ◽

Natalia I. Vetrova ◽

Fedor I. Zhimulev ◽

Simon Nachtergaele ◽

...

Keyword(s):

Tectonic Evolution ◽

Fission Track ◽

Analytical Data ◽

Tectonic Activity ◽

Apatite Fission Track ◽

Tectonic Processes ◽

Basement Rocks ◽

Fission Track Thermochronology ◽

History Of ◽

West Siberian Basin

The West Siberian Basin (WSB) is one of the largest intracratonic Meso-Cenozoic basins in the world. Its evolution has been studied over the recent decades; however, some fundamental questions regarding the tectonic evolution of the WSB remain unresolved or unconfirmed by analytical data. A complete understanding of the evolution of the WSB during the Mesozoic and Cenozoic eras requires insights into the cooling history of the basement rocks as determined by low-temperature thermochronometry. We presented an apatite fission track (AFT) thermochronology study on the exposed parts of the WSB basement in order to distinguish tectonic activation episodes in an absolute timeframe. AFT dating of thirteen basement samples mainly yielded Cretaceous cooling ages and mean track lengths varied between 12.8 and 14.5 μm. Thermal history modeling based on the AFT data demonstrates several Mesozoic and Cenozoic intracontinental tectonic reactivation episodes affected the WSB basement. We interpreted the episodes of tectonic activity accompanied by the WSB basement exhumation as a far-field effect from tectonic processes acting on the southern and eastern boundaries of Eurasia during the Mesozoic–Cenozoic eras.

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Using Fission-Track Radiography Coupled with Scanning Electron Microscopy for Efficient Identification of Solid-Phase Uranium Mineralogy at a Former Uranium Pilot Mill (Grand Junction, Colorado)

Geosciences ◽

10.3390/geosciences11070294 ◽

2021 ◽

Vol 11 (7) ◽

pp. 294

Author(s):

Raymond H. Johnson ◽

Susan M. Hall ◽

Aaron D. Tigar

Keyword(s):

Fission Track ◽

Solid Phase ◽

Nuclear Research ◽

Thin Sections ◽

Nuclear Research Reactor ◽

Elemental Data ◽

Individual Grains ◽

Scanning Electron ◽

Section Sample

At a former uranium pilot mill in Grand Junction, Colorado, mine tailings and some subpile sediments were excavated to various depths to meet surface radiological standards, but residual solid-phase uranium below these excavation depths still occurs at concentrations above background. The combination of fission-track radiography and scanning electron microscope energy-dispersive X-ray spectroscopy (SEM-EDS) provides a uniquely efficient and quantitative way of determining mineralogic associations of uranium that can influence uranium mobility. After the creation of sample thin sections, a mica sheet is placed on those thin sections and irradiated in a nuclear research reactor. Decay of the irradiated uranium creates fission tracks that can be viewed with a microscope. The fission-track radiography images indicate thin section sample areas with elevated uranium that are focus areas for SEM-EDS work. EDS spectra provide quantitative elemental data that indicate the mineralogy of individual grains or grain coatings associated with the fission-track identification of elevated uranium. For the site in this study, the results indicated that uranium occurred (1) with coatings of aluminum–silicon (Al/Si) gel and gypsum, (2) dispersed in the unsaturated zone associated with evaporite-type salts, and (3) sorbed onto organic carbon. The Al/Si gel likely formed when low-pH waters were precipitated during calcite buffering, which in turn retained or precipitated trace amounts of Fe, As, U, V, Ca, and S. Understanding these mechanisms can help guide future laboratory and field-scale efforts in determining long-term uranium release rates to groundwater.

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Exhumation history of late Mesozoic intrusions in the Tongling–Xuancheng area of the Lower Yangtze region, eastern China: Evidence from zircon (U–Th)/He and apatite fission track thermochronology

Ore Geology Reviews ◽

10.1016/j.oregeorev.2021.104220 ◽

2021 ◽

pp. 104220

Author(s):

Yongsheng Wang ◽

Qiao Bai ◽

Ziqiang Tian ◽

Sanming Lu ◽

Jianshe Li ◽

...

Keyword(s):

Fission Track ◽

Eastern China ◽

Apatite Fission Track ◽

Late Mesozoic ◽

Lower Yangtze Region ◽

Fission Track Thermochronology ◽

History Of ◽

Lower Yangtze ◽

Exhumation History

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Prehistorical Obsidian Sources in the Island of Lipari (Aeolian Islands)

Open Archaeology ◽

10.1515/opar-2020-0119 ◽

2020 ◽

Vol 6 (1) ◽

pp. 393-402

Author(s):

Maria Clara Martinelli ◽

Mauro Coltelli ◽

Marco Manni ◽

Letizia Bonizzoni ◽

Alessandra Guglielmetti ◽

...

Keyword(s):

Fission Track ◽

Scientific Research ◽

Raw Material ◽

Neolithic Period ◽

Study Analysis ◽

Geological Samples ◽

Aeolian Islands ◽

Methodological Aspects ◽

And Diffusion ◽

Age Determinations

AbstractThis research project concerns the study, analysis and dating of obsidian flows on the island of Lipari, in relation to the population of the Aeolian Islands, during the Neolithic period.The collection, processing and diffusion of Lipari obsidian characterise the Neolithic population of Lipari and the entire Mediterranean. By improving the knowledge of supply methods in the territory, it will be possible to formulate hypotheses on the chronology of the sources, the ways of collecting the raw material and on the mobility of the Neolithic communities in the Aeolian Islands. The scientific research is divided into two main topics: the first concerns the analytical and methodological aspects of archaeological and geological studies of Lipari obsidian; the second, the formation of obsidian at Lipari, their sources and lithological characteristics. Throughout the duration of this study we will perform new age determinations of Neolithic obsidian artefacts and geological samples, directly with the method of fission track, and indirectly dating paleo soils using the radiocarbon method.

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