منابع مشابه
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...
متن کاملSi isotope variability in Proterozoic cherts
We report Si-isotopic compositions of 75 sedimentologically and petrographically characterized chert samples with ages ranging from 2600 to 750 Ma using multi-collector inductively coupled plasma mass spectrometry. dSi values of the cherts analyzed in this study show a 7& range, from 4.29 to +2.85. This variability can be explained in part by (1) simple mixing of silica derived from continental...
متن کاملSediment mixing in the tropical Pacific and radiolarian stratigraphy
[1] The reworking of older radiolarian microfossils into near-surface sediments of the tropical Pacific has long been the source of confusion for the development of radiolarian stratigraphy and of puzzlement over the mechanism(s) that could effect such pervasive reworking. Widespread dissolution “pits” in the sediments of the tropical Pacific are believed to be associated with hydrothermal circ...
متن کاملthe u.s. policy in central asia and its impact on the colored revolutions in the region (the case study of tulip revolution in kyrgyzstan)
چکیده ندارد.
15 صفحه اولDating carbonaceous matter in archean cherts by electron paramagnetic resonance.
Ancient geological materials are likely to be contaminated through geological times. Thus, establishing the syngeneity of the organic matter embedded in a mineral matrix is a crucial step in the study of very ancient rocks. This is particularly the case for Archean siliceous sedimentary rocks (cherts), which record the earliest traces of life. We used electron paramagnetic resonance (EPR) for a...
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ژورنال
عنوان ژورنال: Geological Magazine
سال: 1902
ISSN: 0016-7568,1469-5081
DOI: 10.1017/s0016756800181658