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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 49 (1965)

Issue: 7. (July)

First Page: 1088

Last Page: 1088

Title: Inter- and Intra-Sequence Faunal Distribution Patterns in the Sacramento Valley Cretaceous: ABSTRACT

Author(s): Gary L. Peterson

Article Type: Meeting abstract

Abstract:

The Cretaceous stratal succession of the Sacramento Valley, California, includes 5 unconformity-bounded sequences designated, in ascending order, Sequences A through E (Peterson, 1964). All are present on the western side of Sacramento Valley. Northward, in the Ono area, Sequences A through D crop out, but at nearby Horsetown only B and D are present. The Redding succession includes Sequences D and E, but at all other exposures on the eastern side of Sacramento Valley, only E is present. Each sequence is almost entirely clastic and wedge-shaped, with the thickest portion toward the west and the thinnest toward the east. Each sequence oversteps the underlying stratal units toward the east where, except for C, each rests on rocks of the Nevadan complex.

Each sequence contains an essentially discrete assemblage of larger marine invertebrates (dominantly Mollusca), having in common only a few species with those either subjacent or suprajacent. Within each sequence, faunas are further distributed so that almost all megafossils occur in the eastern and basal portions; the western portions thus contain few megafossils except near the bases of A and D. The Buchia crassicollis fauna and the Hertleinites aguila and Shasticrioceras poninte zones occur in Sequence A of Neocomian age. Sequence B, of late Aptian and Albian age, contains the Gabbioceras wintunium, Acanthohopiites gardneri, A. reesidei, Leconteites lecontei, Beudanticeras hulenense, Oxytropidoceras packardi, and Mortoniceras hulenanum zones. Sequence C, of Cenomanian age, contains an unnamed fauna. Sequence D, of Turonian age, contains the Glycymeris pacificus fauna, and Sequence E, of Senonian age, contains the Glycymeris veatchii fauna. The bases of A, B, and D (and possibly all) are temporally variant and transgressive from west to east.

Apparently these 5 sequences, together with their distribution and thickness relations, discrete faunas, intra-sequence faunal distribution patterns, and age relations, are the physical and biostratigraphic manifestations of 5 successive transgressive-regressive episodes and probably are related to diastrophism generated toward the east.

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Copyright 1997 American Association of Petroleum Geologists