The Fluvial Geochemistry of the Rivers of Eastern Siberia and Implications for the Effect of Climate on Weathering
The dependence of weathering on climate (temperature and precipitation) forms the core of a negative feedback proposed to have maintained the Earth's atmospheric CO2 within habitable limits for most of its history. This hypothesis has not been proven from field results. Data for chemical compos...
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| Format: | Text |
| Language: | English |
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1998
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| Online Access: | http://www.dtic.mil/docs/citations/ADA363530 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA363530 |
| Summary: | The dependence of weathering on climate (temperature and precipitation) forms the core of a negative feedback proposed to have maintained the Earth's atmospheric CO2 within habitable limits for most of its history. This hypothesis has not been proven from field results. Data for chemical compositions and fluxes of periglacial rivers of the Russian Far East-the Lena, Yana, Indigirka, Kolyma, and Anadyr-were acquired and compared to the published dataset on tropical watersheds. Three broad geological divisions are made to facilitate the comparison-the stable basement shield, region of uplift and mountain building, and the sedimentary platform. In all three geologic regions no climatic effect on the rate of uptake of CO2 by aluminosilicate weathering (Phi-CO2) was observed. This appears to be due to the unique non-glacial frost shattering processes which expose fresh rock surfaces and thus overcome the effect of temperature inhibition at high-latitudes. On the tropical shields, the lateritic cover builds up due to lack of topography, seals the weathering front from the climatic agents, and lowers weathering rates. There appear to be no primary climatic effects on weathering rates on the present Earth. |
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