Paleogeology

Paleogeology, Paleoclimate, in relation to Evolution of Life on Earth

hydrothermal metamorphism

Hydrothermal metamorphism results from the interaction of a rock with high-temperature fluids, producting metamorphic and metasomatic reactions that depend upon temperature and compositional differences between the country rock and the invading fluid.

The hydrothermal fluid may be:
● magmatic (originating in an intruding magma)
● circulating groundwater
● ocean water

Convective circulation of saline in ocean floor basalts produces extensive hydrothermal metamorphism adjacent to spreading centers and in other submarine volcanic areas. Patterns of hydrothermal alteration are used as guides in the search for deposits of valuable metallic ores.

[links: images: pyritized rocks (form a halo around the copper deposit) and result from percolation of chemically-reactive hot groundwaters through the strata]

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. . . stratifying since 10/06/06