Paleo-environmental interpretation of Paleocene Sepultura Formation in type locality, Mesa La sepultura, Baja California, Mexico
Conference
·
· AAPG Bull.; (United States)
OSTI ID:6639440
The Sepultura Formation in its type locality consists of two major lithostratigraphic units. The basal A unit overlies the Cretaceous Rosario Formation. It consists predominantly of fine-grained, poorly consolidated sandstones; some conglomerates; and thin beds of well-consolidated lenticular fossiliferous sandstones, which show some cyclic sedimentation. The poorly consolidated sandstones contain glauconitic layers; abundant shark teeth, benthic forams, and ostracods; and sparse mollusks, brachiopods, and Ophiomorpha-like trace fossils. These faunas indicate deposition in nearshore shallow waters. The interbedded consolidated lenticular sandstones probably indicate storm-induced deposition below wave base. This mechanism is assumed to be responsible for the high concentration of fossils consisting predominantly of unworn molluscan shells, scaphopods, echinoid spines, corals, and forams. In places, the elongated shells of Turritella pachecoensis show a preferential orientation to the southwest. At the top of the unit, a poorly fossiliferous red conglomerate indicates deltaic conditions. Overlying the conglomerate is unit B which shows a change in the sedimentary environment. It consists of a calcareous shallowing upward sequence of nodular to massive algal limestone with caliche at top. The microfossils of this unit show glauconitization in places, and consist, in addition to algal fragments, of forams, microscopic mollusks, and some ostracods and calcispherules from shallow waters (less than 30 m deep).
- Research Organization:
- Museo Regional Universitario, Mexicali (Mexico)
- OSTI ID:
- 6639440
- Report Number(s):
- CONF-8804144-
- Conference Information:
- Journal Name: AAPG Bull.; (United States) Journal Volume: 72:3
- Country of Publication:
- United States
- Language:
- English
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Fri May 01 00:00:00 EDT 1987
· AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States)
·
OSTI ID:5999898
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·
Sun Mar 31 23:00:00 EST 1985
· Am. Assoc. Pet. Geol., Bull.; (United States)
·
OSTI ID:5857613
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·
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· Geol. Soc. Am., Abstr. Programs; (United States)
·
OSTI ID:6454990
Related Subjects
02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
CLAYS
CONGLOMERATES
CRETACEOUS PERIOD
DEPOSITION
DEVELOPING COUNTRIES
FOSSILS
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGY
LATIN AMERICA
LITHOLOGY
MESOZOIC ERA
MEXICO
NORTH AMERICA
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
STRATIGRAPHY
020200* -- Petroleum-- Reserves
Geology
& Exploration
CLAYS
CONGLOMERATES
CRETACEOUS PERIOD
DEPOSITION
DEVELOPING COUNTRIES
FOSSILS
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGY
LATIN AMERICA
LITHOLOGY
MESOZOIC ERA
MEXICO
NORTH AMERICA
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
STRATIGRAPHY