Hydrocarbons Associated with Fluid Venting Process in Monterey Bay, California

by T. D. Lorenson, K. A. Kvenvolden, F. D. Hostettler, R. J. Rosenbauer, J. B. Martin, and D. L. Orange

Site Map

Poster Layout

Introduction

Index Map

Cold Seep Hydrocarbon Gases

Sediment Hydrocarbons

Cooperators

Credits

Caveat

Data

Smooth Ridge Samples

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Three separate clam colonies were sampled for sediment gases and pore water chemistry on two separate occasions. Sediment near carbonate crusts and ridges was also sampled once. Methane and ethane concentrations are shown as blue and red bars, respectively, with the carbon isotopic composition of methane. The majority of hydrocarbon gas is methane. Ethane concentrations are relatively high for surficial marine sediment, occurring only within the clam colonies. Trace amounts of propane, butane, and pentane were also noted. These gases commonly appear in thermogenic fluids which may migrate up from depths of 2-3 kilometers along conduits.