--> Stratigraphy and Distribution of Lithofacies Associations in a Structurally Confined Turbidite System: The Upper Modelo Formation in Eastern Ventura Basin, California
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Pacific Section AAPG, SPE and SEPM Joint Technical Conference

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Stratigraphy and Distribution of Lithofacies Associations in a Structurally Confined Turbidite System: The Upper Modelo Formation in Eastern Ventura Basin, California

Greg Gordon1 and David Pyles2

1Aera Energy
2Chevron Center of Research Excellence at the Colorado School of Mines

April 29, 2014 Tuesday 4:00 P.M. Pacific Section AAPG, SPE and SEPM Joint Technical Conference, Bakersfield, California

Abstract

Outcrops of the Miocene upper Modelo Formation in the eastern Ventura basin, California, represent a longitudinal transect through a fault-controlled deepwater depositional system, from proximal structural terraces, through a submarine canyon, to the Previous HitbasinNext Hit Previous HitfloorNext Hit and Previous HitbasinNext Hit margin. This study area is divided into three regions based on geographic location, stratigraphic character, and interpreted paleogeographic environment: Region 1 (Feeder System), Region 2 (Proximal Previous HitBasinNext Hit Previous HitFloorNext Hit), and Region 3 (Medial-Distal Previous HitBasinNext Hit Previous HitFloorNext Hit). Region 1 contains interpreted syndepositionally active normal faults (e.g., Devil Canyon fault) near the proximal basin margin; these faults are associated with abrupt changes in depositional environments, lithofacies associations, paleobathymetry, and stratigraphic thickness. The adjacent submarine canyon was an area of bypass, yet there are sand-rich submarine channels located within it. This area has a relatively low net-sandstone content overall. Isopach maps reveal that gross thickness is greatest near the interpreted canyon mouth. In Region 2, a proximal-Previous HitbasinNext Hit-Previous HitfloorNext Hit fairway located immediately basinward of the canyon contains the highest sandstone content in the basin. This fairway comprises a number of channel complexes, mostly characterized by amalgamated, medium-grained-to-pebbly sandstone lithofacies. In Region 3, gradual changes in proportions of lithofacies associations result from subtle variations in the gradient of the Previous HitbasinNext Hit Previous HitfloorTop near the lateral/distal basin margin, as interpreted from the isopach map. In this area, channel complexes comprising structureless, amalgamated sandstone overlie thin-to-medium bedded, “dirty” sandstones deposited at the fringes of lobes. This upward architectural pattern is interpreted to result from an outwardly expanding depocenter through time.

AAPG Datapages/Search and Discovery © 2014 Pacific Section AAPG, SPE and SEPM Joint Technical Conference, Bakersfield, California, April 27-30, 2014