T118 Geochemical Signatures of Fluid-Rock Interaction: Earth Surface Weathering to Hydrothermal Systems II

Wednesday, 28 October 2020
10:00 AM - 12:00 PM
Meeting Rooms

EVOLVING GEOCHEMISTRY OF SERPENTINITE-HOSTED WATERS

Paper number: T118-7
Program: Technical Sessions
Time: 11:30 AM – 11:45 AM

Authors

  • Dawn Cardace Presenting Author
    University of Rhode Island, Kingston, RI

Abstract

Serpentinization is a long duration, expansive geologic process exhibiting punctuated equilibrium characteristics. Olivine and pyroxene minerals in parent rocks alter to serpentine-dominated assemblages; overall, ferrous iron is oxidized and hydrogen in molecular water is reduced to diatomic hydrogen, generating daughter materials generally more hydrated, oxidized, and diverse when compared to parent materials. Depending on tectonic history and weathering patterns, sequential, distinct periods of water-rock interaction imprint mineralogically in the host rock and drive changes in the geochemistry of through-flowing waters. I propose that these be viewed in the context of quasi-stable systems within a punctuated equilibrium framework. Geochemical modeling results support this framework, and field and analytical observations (XRD data, thin section analyses) of Coast Range Ophiolite ultramafic units (Lower Lake, CA locality) serve as a case study. Wide-reaching implications for elemental cycling, gas evasion, and support of the resident chemosynthetic biosphere are considered.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-357283

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