Coast Geological Society

Ventura, California

Please Join CGS on Tuesday December 18th, 2018

Thomas L. Davis, Ph.D., and State Professional Geologist, will give his talk titled:

Petroleum geology comparison of the San Andreas fault plate boundary, California, USA to the Sagaing fault plate boundary, Myanmar (Burma): structural style, oil field traps, tectonic setting, and basin development

Petroleum geology comparison of the San Andreas fault plate boundary, California, USA to the Sagaing fault plate boundary, Myanmar (Burma): structural style, oil field traps, tectonic setting and basin development


Abstract:


The San Andreas fault (SAF) and the Sagaing fault (SF) are the principal structures of seismically active transpressional plate boundaries with similar structural style, ages of deformation, and oil- trapping mechanisms. Both faults have ~300 km of post-Oligocene right-lateral slip, adjacent to fold and thrust belts developed since the late Miocene, oil fields with numerous structural traps, and actively-generating petroleum systems. The oil-rich basins along the SAF plate boundary are data-rich and concepts learned over the last 50 years can be used to explore in the Central Burma Depression (CBD) and to develop its oil fields. Along the SAF plate boundary, the results of exploration drilling, oil field development, reflection seismic data, and earthquake characteristics are consistent with development of a fold and thrust belt that results from strain-partitioning of plate motions. Within the belt are fault-related folds and thrust faults that flatten with depth, providing subthrust exploration traps with known oil source and reservoir rocks. The oil-rich CBD is deformed in a similar style and opportunities, and many of its oil field traps are fault- propagation- and detachment-origin anticlines in need of development drilling. The SF plate boundary between the Indian and Sunda (Asia) plates is comparable to the pre-Oligocene setting along the western edge of North America with similar, spatially-arranged tectonic elements. That is the Farallon and India subducting plates, California Coast Ranges and Indo-Burma Ranges fold and thrust belts and accretionary wedges, pre-Oligocene San Joaquin basin and CBD, and Sierra Nevada and Popo-Taungthanlon magmatic arcs. Temperature differences between the subducting plates may explain the differing positions of the SF and SAF in this arrangement. The petroleum potential differences between the CBD and the California oil basins result from post- Oligocene basin development, shallow-marine versus deep-marine, respectively.


Thomas L. Davis, Ph.D.
Bio:

Thomas L. Davis is a California State Professional Geologist (#4171), owner of Thomas L. Davis Geologist and President of the nonprofit Geologic Maps Foundation, Inc., researcher and author of geologic publications dealing with structural geology, active faulting and earthquakes, oil and gas fields, gas storage fields, and the petroleum potential of central and southern California, Nevada, the Indian subcontinent, and northwestern South America. Davis has a BS and PhD from the University of California. In two papers published in 1988, Jay Namson and Davis showed that the destructive 1983 Coalinga earthquake occurred on a blind-thrust-fault beneath the Coalinga anticline, that the deformed west-side of the San Joaquin basin is an seismically-active convergent wedge, the western Transverse Ranges are an active fold and thrust belt with strain-partitioning along the San Andreas plate boundary, and more generally that subsurface geology needed to be integrated with surface geology to have a more complete understanding of earthquake hazard and risk (Seismically Active Fold and Thrust Belt in the San Joaquin Valley, Central California, GSA Bulletin, v.100, p. 257- 273; and Structural Transect of the Western Transverse Ranges, California: Implications for Lithospheric Kinematics and Seismic Risk Evaluation, Geology, v.16, p.675-679). In 1989, Davis, Namson, and Bob Yerkes were the first to show that the deformed margin of the northern Los Angeles basin was underlain by an active, north-dipping blind-thrust fault system (Elysian Park) and a splay fault of this system caused the destructive 1987 Whittier Narrow earthquake (A Cross Section of The Los Angeles Area; Seismically Active Fold And Thrust Belt, The 1987 Whittier Narrows Earthquake, and Earthquake Hazard, JGR, v. 94, p.9644-9664). Again, their approach emphasized integrating surface and subsurface geology and using interpretative subsurface mapping techniques, software, and data used almost exclusively by the oil and gas industry to fully understand the geology and seismic hazards of an area. Davis and Namson interpreted that the 1994 Northridge earthquake occurred along a deep, south-dipping blind thrust fault (Pico) whose surface expression is the extensive northeast-dip of the northern Santa Susana Mountains, and the Santa Susana fault is possibly a roof thrust to a northward-directed crustal wedge (A Balanced Cross-Section of the 1994 Northridge Earthquake, Southern California; Nature, v. 372, no. 10, p.167-169). Davis continues to emphasize the need to integrate surface and subsurface geologic data to the geologic community.


Visit Thom's websites for his publications and field guidebook

Thom's personal website: www.thomasldavisgeologist.com 

Geologic Map Foundation: www.geologicmapsfoundation.org

Headline

The monthly CGS meeting is held at the Poinsettia Pavilion in Ventura!

Meeting Schedule:

6:00 - 7:00 PM: Social Hour - Snacks and Beverages 

7:00 - 7:30 PM: Dinner Service

7:30 - 8:00 PM: Announcements & Raffle

8:00 - 9:00 PM:  Main Presentation


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