The significance of galena Pb model ages and the formation of large Pb-Zn sedimentary deposits
نویسندگان
چکیده
In an attempt to clarify the significance of Pb model ages in Pb-Zn sedimentary deposits, we report high-precision isotopic compositions for 64 galenas and 52 K-feldspars, former from ores latter separated granites. All samples are Spain French Pyrenees. Lead galena is unequivocal continental origin. With few exceptions, systematically exceed emplacement by up 400 Ma, a gap which well outside uncertainties ~ 30 Ma assigned model. The histogram new isotope data shows prominent peaks at 94 ± 38 392 39 Ma. When consolidated with literature examined 3-dimensional space, cluster analysis identifies five groups. occur, order decreasing peak intensity, 395 40 (Middle Devonian), 90 34 Cretaceous), 613 42 (Neoproterozoic), two minor 185 + 26 (Jurassic) 313 41 (Upper Carboniferous). To large extent, centered around these correspond distinct localities. do not coincide any Betic, Variscan, or Pan-African tectonic events, main episodes that shaped Iberian geology, but instead match well-known global oceanic anoxic events. It argued surges metals weathered surfaces scorched during events accumulated combined water masses unoxidized marine sulfide released submarine hydrothermal activity precipitate primary stock. Frozen require black shales source final ores. sulfides were later remobilized large-scale convective circulation basinal fluids. K-feldspar those correlate magmatic ages. suggested they reflect local Paleozoic sediments surrounding individual plutons. While isotopes can be used as regional provenance tool, such approach requires considered fully space.
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ژورنال
عنوان ژورنال: Chemical Geology
سال: 2021
ISSN: ['0009-2541', '1872-6836']
DOI: https://doi.org/10.1016/j.chemgeo.2021.120444