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Sedimentary and Structural Evolution of the Neogene Salinas Basin, California: Implications for Burial History Modeling of a Strike-Slip Basin

Menotti, Tess; Meisling, Kristian; and Graham, Stephan A.
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We present a tectonic and sedimentary history of the southern Salinas Basin based on new 3-D seismic reflection data, integrated with well log and outcrop-based mapping. Our interpretation has implications for framing a greater understanding of the development of basins along transform plate margins. Our interpretation provides a basis for including burial due to sedimentation and structural deformation in one-dimensional (1-D) burial history models of the Salinas Basin. Inferences of relative timing of subsidence, deposition, uplift and inversion episodes provide constraints on burial history scenarios.

Located in the Coast Ranges of central California, the Salinas Basin records a Neogene history that has been largely controlled by Pacific/North-American plate interactions along the San Andreas strike-slip system. The southern Salinas Basin contains over 3 km (~10,000 ft) of mid-late Miocene Monterey Formation. This thickness is attributed to the tectonic history of the region, including mid-Miocene subsidence due to transtension, and subsequent phases of transpression, as well as both syn- and post-Monterey Fm deposition. Prior surface stratigraphic and structural mapping is integrated with our observations of the geometry of subsurface stratigraphic packages and structural deformation revealed by 3-D seismic reflection data. We see seismic evidence for an early-mid Miocene transtensional phase, followed by multiple episodes of transpression, which ultimately led to partial inversion of the basin. Transtensional basement faults provided a mechanism for initial accommodation in the early-mid Miocene. A shift toward a compressional phase in late Miocene led to formation of at least one detachment that soles out within the sedimentary section, perhaps in a mechanically weak stratigraphic zone. This detachment cuts upsection and ramps up over basement fault blocks, eventually joining and inverting along antecedent extensional faults. This faulting ceased prior to the early Pliocene, as evidenced by an over-lapping, southeast-prograding clinoform package. We also see stratigraphic evidence for transpressional fold growth during deposition of the Monterey Fm, which ceased by the early Pliocene. A transpressional phase at least as young as late Pliocene is documented by uplifted and broadly folded Neogene strata, including the Pliocene clinoform package. These observations provide conceptual basis for 1-D burial history models using PetroMod® basin modeling software.

 

AAPG Search and Discovery Article #90162©2013 Pacific Section AAPG, SPE and SEPM Joint Technical Conference, Monterey, California, April 19-25, 2013