Controls on the formation of early diagenetic dolomite, Monterey Formation, California

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6877336

Compton, J S; Siever, R

The clayey siliceous and phosphatic Monterey Formation in the Santa Maria basin contains 1 to 40 wt % dolomite, whose stratigraphic occurrence is relatable to sediment composition which in turn is dependent on climatic variations. Early dolomite is commonly associated with laminated, organic-rich, calcareous, phosphatic sediment in which organic carbon, pyritic sulfur, V, and Cu are positively correlated. The amounts of organic matter and calcite affect the extent of early dolomite precipitation. Bacterial degradation of sediment organic matter reduces sulfate to H/sub 2/S and increases the carbonate alkalinity, highly supersaturating pore waters with respect to dolomite. Mg transport by diffusion from overlying sea water constrains the bulk of the dolomite to have formed during early diagenesis, in agreement with field evidence of precompaction origin. Ultimately Monterey sediment composition was influenced by the effects of climatic oscillations on surface water productivity. Global temperature decrease accelerates atmospheric and oceanic circulation and O/sub 2/ renewal rates to deep waters and deepens the carbonate compensation depth (CCD), thereby limiting organic matter and calcite preservation. Organic-rich sediment forms both in upwelling regions because of high surface productivity and infringement of an expanded O/sub 2/-minimum zone, and in basins where circulation is restricted by topography. Calcite content depends on the silica/calcite ratio of the surface productivity and on the CCD and basin bathymetry.

• Research Organization: Harvard Univ., Cambridge, MA (USA)
• OSTI ID: 6877336
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580100* -- Geology & Hydrology-- (-1989)
580400 -- Geochemistry-- (-1989)
ALKALINE EARTH METAL COMPOUNDS
CALCITE
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CALIFORNIA
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CHALCOGENIDES
CHEMISTRY
DIAGENESIS
DOLOMITE
FEDERAL REGION IX
GEOCHEMISTRY
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
GEOLOGY
IRON COMPOUNDS
IRON SULFIDES
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MINERALOGY
MINERALS
NORTH AMERICA
ORGANIC MATTER
OXYGEN COMPOUNDS
PALEOCLIMATOLOGY
PALEONTOLOGY
PRECIPITATION
PYRITE
SEASONAL VARIATIONS
SEDIMENTARY BASINS
SEDIMENTS
SEPARATION PROCESSES
STRATIGRAPHY
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
SULFUR CONTENT
TRANSITION ELEMENT COMPOUNDS
USA
VARIATIONS