7 research outputs found
Distribution, Microfabric, and Geochemical Characteristics of Siliceous Rocks in Central Orogenic Belt, China: Implications for a Hydrothermal Sedimentation Model
Marine siliceous rocks are widely distributed in the central orogenic belt (COB) of China and have a close connection to the geological evolution and metallogenesis. They display periodic distributions from Mesoproterozoic to Jurassic with positive peaks in the Mesoproterozoic, CambrianāOrdovician, and CarboniferousāPermian and their deposition is enhanced by the tensional geological settings. The compressional regimes during the Jinning, Caledonian, Hercynian, Indosinian, and Yanshanian orogenies resulted in sudden descent in their distribution. The siliceous rocks of the Bafangshan-Erlihe ore deposit include authigenic quartz, syn-depositional metal sulphides, and scattered carbonate minerals. Their SiO2 content (71.08ā95.30%), Ba (42.45ā503.0āppm), and Ī£REE (3.28ā19.75āppm) suggest a hydrothermal sedimentation origin. As evidenced by the Al/(Al + Fe + Mn), Sc/Th, (La/Yb)N, and (La/Ce)N ratios and Ī“Ce values, the studied siliceous rocks were deposited in a marginal sea basin of a limited ocean. We suggest that the Bafangshan-Erlihe area experienced high- and low-temperature stages of hydrothermal activities. The hydrothermal sediments of the former stage include metal sulphides and silica, while the latter was mainly composed of silica. Despite the hydrothermal sedimentation of the siliceous rocks, minor terrigenous input, magmatism, and biological activity partly contributed to geochemical features deviating from the typical hydrothermal characteristics
Distribution, Microfabric, and Geochemical Characteristics of Siliceous Rocks in Central Orogenic Belt, China: Implications for a Hydrothermal Sedimentation Model
Marine siliceous rocks are widely distributed in the central orogenic
belt (COB) of China and have a close connection to the geological
evolution and metallogenesis. They display periodic distributions from
Mesoproterozoic to Jurassic with positive peaks in the Mesoproterozoic,
Cambrian-Ordovician, and Carboniferous-Permian and their deposition is
enhanced by the tensional geological settings. The compressional regimes
during the Jinning, Caledonian, Hercynian, Indosinian, and Yanshanian
orogenies resulted in sudden descent in their distribution. The
siliceous rocks of the Bafangshan-Erlihe ore deposit include authigenic
quartz, syn-depositional metal sulphides, and scattered carbonate
minerals. Their SiO2 content (71.08-95.30%), Ba (42.45-503.0 ppm), and
Sigma REE (3.28-19.75 ppm) suggest a hydrothermal sedimentation origin.
As evidenced by theAl/(Al + Fe + Mn), Sc/Th, (La/Yb)(N), and (La/Ce)(N)
ratios and delta Ce values, the studied siliceous rocks were deposited
in a marginal sea basin of a limited ocean. We suggest that the
Bafangshan-Erlihe area experienced high-and low-temperature stages of
hydrothermal activities. The hydrothermal sediments of the former stage
include metal sulphides and silica, while the latter was mainly composed
of silica. Despite the hydrothermal sedimentation of the siliceous
rocks, minor terrigenous input, magmatism, and biological activity
partly contributed to geochemical features deviating from the typical
hydrothermal characteristics