Joint Meeting Pacific Section, AAPG & Cordilleran Section GSA April 29–May 1, 2005, San José, California
Outcrop Characterization of Channelized Deep-Water Deposits, Carmelo Formation, Point Lobos State Reserve, Northern California
Steven Springhorn, Ryan Alward, Morgan Sullivan, Bryan Demucha, Sean Spaeth, Margaret Skartvedt-Forte, and Nick Lawlor
Department of Geological and Environmental Sciences, California State Univ, Chico, CA 95929, [email protected]
The purpose of this research was to characterize the vertical and lateral changes in the fill of individual deep-water channels which comprise the Carmelo Formation at Point Lobos State Reserve, south of Carmel, California. This information can be used to provide geostatistical data required to construct geologic (aquifer/reservoir) models to better understand and predict fluid flow in subsurface sandstones. This was accomplished by measuring detailed stratigraphic sections at extremely close spacing (approximately 12 meters) and correlating individual beds between each section to construct a detailed stratigraphic panel. Facies proportions, bed thicknesses/lengths data and channel dimensions were then collected and analized. The outcrop of the Carmelo Formation exposed at “The Slot” is composed of compensationally stacked, erosionally confined channels. Individual channels are 10 to 20 meters thick and estimated to be 100's of meters in width. Based on this analysis channels have width to thickness ratios of 15:1 to 20:1. These channel-fills also display distinct lateral facies variations in facies. Channel-axis deposits are dominated by tractively deposited, normally graded, clast supported conglomerate and lesser amounts of shale clast conglomerate. These deposits grade laterally into non-amalgamated, thick-bedded massive sandstones which represent channel off-axis deposits. The channel margin deposits consist of interbedded thick- to medium-bedded massive sandstones, thin-bedded sandstones and shales. Slump deposits are also locally present and are probably related channel margin failure. This research was supported by a research grant from ChevronTexaco.
Posted with permission of The Geological Society of America; abstract also online (http://gsa.confex.com/gsa/2005CD/finalprogram/abstract_85596.htm). © Copyright 2005 The Geological Society of America (GSA).