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Title: Forward modeling of high-frequency, glacio-eustatic, depositional sequences: An example from Middle Pennsylvanian shelf carbonates of the SW Paradox basin, Honaker Trail, Utah

Conference · · AAPG Bulletin (American Association of Petroleum Geologists); (USA)
OSTI ID:6755082
;  [1];  [2]
  1. Exxon Production Co., Houston, TX (USA)
  2. State Univ. of New York, Stony Brook (USA)

Middle Pennsylvanian (Desmoinesian) shelf carbonates in the southwest Paradox basin display three superimposed orders of stratigraphic cyclicity with a systematic, vertical succession of facies, parasequence, and sequence stacking patterns. Fifth-order parasequences (34 parasequences in 645 ft section; averaging 20 ft thick, 40 k.y. duration) are grouped into fourth-order sequences (averaging 100 ft thick approximately 400 ky. duration), which in turn vertically stack to define a third-order accommodation cycle ({>=} 650 ft thick 2.4 m.y. duration). Fifth-order parasequences are comprised of shallowing-upward packages of dominantly subtidal shelf carbonates with sharp parasequence boundaries (exposure or flooding surfaces). Fifth-order parasequences are packaged into fourth-order sequences (type 1) bounded by regionally correlative subaerial exposure surfaces. These type 1 sequences contain a downdip, basinally restricted lowstand wedge of evaporites and quartz clastics, a regionally correlative transgressive shaly mudstone (condensed section), and a highstand systems tract composed of thinning-upward, aggradational, fifth-order parasequences. Systematic variation in the thickness of fourth-order sequences (thinning followed by upward thickening), as well as the number of fifth-order parasequences/sequences (decreasing followed by increasing number), define a third-order accommodation trend, which is also regionally correlative. High-frequency parasequences and sequences are interpreted as aggradational allocycles generated in response to glacio-eustatic sea level fluctuations driven by Milankovitch climatic forcing. The fifth-order parasequences record the earth's orbital eccentricity cycle (mean period of 41 ky.), and the fourth-order sequences result from the long eccentricity cycle (mean period of 413 k.y.).

OSTI ID:
6755082
Report Number(s):
CONF-900605-; CODEN: AABUD
Journal Information:
AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:5; Conference: Annual convention and exposition of the American Association of Petroleum Geologists, San Francisco, CA (USA), 3-6 Jun 1990; ISSN 0149-1423
Country of Publication:
United States
Language:
English