T27 Challenges in Tectonics: Planetary Evolution in Four Dimensions—The New Global Tectonics

Sunday, 22 October 2017
8:00 AM - 12:00 PM
Tahoma 4

A FOUR-DIMENSIONAL MODEL OF CRETACEOUS DEPOSITIONAL GEOMETRY AND SEDIMENT FLUX IN THE NORTHERN GREAT VALLEY FOREARC, CALIFORNIA

Paper number: T27-4
Program: Technical Sessions
Time: 8:50 AM – 9:05 AM

Authors

Abstract

The Great Valley forearc records Jurassic-Eocene sedimentation along the western margin of North America during eastward subduction of the Farallon plate and development of the Sierra Nevada magmatic arc. This study presents the first 4-D basin model of the northern Great Valley forearc designed to reconstruct its depositional history from the Tithonian through the Maastrichtian. Using >1200 boreholes, we identify the tops of 13 horizons and produce a new series of isopach maps and cross-sections that highlight the spatial and temporal variability along and across the basin. The model shows the southward deepening of the basin during the Cretaceous and eastward onlapping of basin strata onto the Sierra Nevada basement. In addition, the model presents the first basement map of the entire Sacramento sub-basin, highlighting its topography at the onset of deposition of the Great Valley Group. Minimum volume estimates for sedimentary basin fill reveal episodic periods of flux, with peak sedimentation corresponding to deposition of the Sites Sandstone in the Coniacian. Comparison of these results with flux estimates from magmatic source regions shows a slight offset in the timing of peak sedimentation, likely reflecting the residence time from pluton emplacement to erosion in the neighboring basin. This model provides the foundation for the first 4D subsidence analysis on an ancient forearc basin, which in turn will yield insight into the mechanisms driving development of accommodation space along convergent margins.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-297669

© Copyright 2017 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.