Nature
Figueroa Sulfide is a small Jurassic hydrothermal vent deposit in California’s San Rafael Mountains, preserved in the Franciscan Complex and dating to about 185 to 181 million years ago. Formed in a deep-sea, subduction-related setting, it includes a sulfide lens with a silicified core surrounded by altered volcanic and sedimentary rocks later modified by tectonic and chemical change. Its greatest importance is scientific rather than economic: fossils and pyrite molds preserve an ancient chemosynthetic vent community that included brachiopods, gastropods, and vestimentiferan tubes. The site contains the oldest confirmed record of Siboglinidae and offers one of the oldest known examples of this type of ecosystem.
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Santa Ynez, California · United States