Biogeochemical signatures preserved in ancient siliceous sediments; new perspectives to Triassic radiolarian bedded chert compositions

Biogeochemical signatures preserved in ancient siliceous sediments; new perspectives to Triassic radiolarian bedded chert compositions

Major and minor elements of successively collected 70 Middle Triassic radiolarian bedded cherts from the Mino Belt in central Japan were studied. In order to reveal pre-diagenetic, primary geochemical signatures related to marine biogeochemical cycles, composite data of chert-shale couplets in addition to raw data were examined. The results show that Mn, Cu, Sr, Ba and P were supplied significa...

Cosmic Spherules from Triassic Deep-sea Sediments in Japan

Introduction: Cosmic spherules are subspherical to spherical particles of <1 mm diameter which are produced by melting of interplanetary dust and large objects during atmospheric entry. Although cosmic spherules are known principally from the ice sheets of polar regions and Cenozoic deep-sea sediments [1-3], a few spherules older than Mesozoic were recovered from the sedimentary rocks of pelagi...

The Igneous End Member Compositions Preserved in Gale Crater Sediments

Magnetite dissolution in siliceous sediments

[1] Magnetite dissolution, and consequent loss of magnetization, is widely observed in reducing sedimentary environments, where the decrease in Eh-pH values with depth is driven by bacterially mediated degradation of organic carbon. We have observed low magnetizations in sediments with elevated pore water silica concentrations that arise from diagenesis of biogenic silica and/or silicic volcani...

New Perspectives on Biogeochemical Exploration

Significant refinements of biogeochemical methods applied to mineral exploration have been made over the past quarter century, with advances on all continents. Databases from surveys around the world provide enhanced information on which species and tissues to collect from all major climatic environments, and how, why and when to sample. Recent commercialization of sophisticated new ICPMS analy...