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Title: Grasslands, silicate weathering and diatoms: Cause and effect

Diatoms are silica-limited, photosynthetic, single-celled eukaryotes that today occupy a wide variety of habitats both in freshwater and marine environments. Ultimately the silica they use is derived from the weathering of silicates on land. Although marine diatoms first appear in the Jurassic, the fossil record shows a remarkable correlation between the Mid-Miocene appearance of widespread grasslands and the drastic increase in diatom-rich deposits in freshwater, as well as in marine environments throughout the world. Grasses actively weather silicates, accumulating soluble silica into their leaves. Decomposing grasses release this soluble silica into the soil from whence it is transported into lakes and oceans and made available to diatoms. Grasses also probably increased chemical weathering, and hence the release of soluble silica, in previously weakly vegetated semi-arid areas. Increased weathering of silicates also led to cooler climates as evidenced by the Mid-Miocene [delta][sup 18]O record. The author suggests that the Tertiary expansion of grasslands is responsible for the explosive increase in diversity and abundance of diatoms in the oceans and freshwaters of the Mid-Miocene.
Authors:
 [1]
  1. (Columbia Univ., Palisades, NY (United States). Dept. of Geological Sciences)
Publication Date:
OSTI Identifier:
5011276
Report Number(s):
CONF-9303210--
Journal ID: ISSN 0016-7592; CODEN: GAAPBC
Resource Type:
Conference
Resource Relation:
Journal Name: Geological Society of America, Abstracts with Programs; (United States); Journal Volume: 25:3; Conference: 27. annual Geological Society of America (GSA) North-Central Section meeting, Rolla, MO (United States), 29-30 Mar 1993
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 59 BASIC BIOLOGICAL SCIENCES; DIATOMS; POPULATION DYNAMICS; GEOLOGIC DEPOSITS; BIOGEOCHEMISTRY; PALEONTOLOGY; SILICON OXIDES; UPTAKE; DECOMPOSITION; GRAMINEAE; RANGELANDS; ALGAE; CHALCOGENIDES; CHEMICAL REACTIONS; CHEMISTRY; CHROMOPHYCOTA; ECOSYSTEMS; GEOCHEMISTRY; LILIOPSIDA; MAGNOLIOPHYTA; OXIDES; OXYGEN COMPOUNDS; PLANTS; SILICON COMPOUNDS; TERRESTRIAL ECOSYSTEMS 580000* -- Geosciences; 550500 -- Metabolism