San Joaquin Basin 2018

The purpose of the field trip was to investigat the Kreyenhagen-Temblor(!) and essential elements of other petroleum systems in the western San Joaquin Basin, California.  During the course of one day, we were able to see all elements of that petroleum system, exposed due to geologically recent uplift/erosion. We explored Big Tar Canyon, a valley near Reef Ridge on the skyline. This ridge is held up by the Temblor Formation of Miocene age. The Kreyenhagen source rock is presently buried in excess of 3 kilometers beneath the cultivated field in the valley floor. Some of the highlights included seeing an active seep of Kreyenhagen-sourced oil near the top of the Kreyenhagen Formation. It was also exciting to study the lithology and the fossils. Down the canyon to the west is the Coalinga oil field Oyster Reef in the estuarine facies of the middle Temblor Formation on Cartwheel Ridge. And we looked for insects stuck in the brea or tar sands of Quaternary age very near the Coalinga oil field production!