Image: Chromitic serpentinite (Little Port Complex, Bay of Islands Ophiolite, Middle Cambrian, 505 Ma; Springer's Hill outcrop, Lewis Hills, Newfoundland) 4

Description: Chromitic serpentinite from the Cambrian of Newfoundland, Canada. Ophiolites are fragments of oceanic lithosphere (basaltic crust + uppermost mantle) that have been metamorphosed and plastered onto the edges of continental lithospheric plates by obduction (the opposite of subduction). A classic place for seeing mantle rocks in an ophiolite is western Newfoundland. This rock is from the upper mantle portion of the Cambrian-aged Little Port Complex. It was originally a chromitic dunite, but it’s been metamorphosed - the olivine has been altered to serpentine (= yellowish-green portions of the rock). The black areas are chromite (FeCr2O4 - iron chromium oxide). The mantle rocks in this area have been inferred to represent the lower lithosphere of an ancient island arc. Geologic unit: Little Port Complex, Lewis Hills Massif, Bay of Islands Ophiolite, late Middle Cambrian, 505 Ma Locality: Springer’s Hill outcrop, Lewis Hills, western Newfoundland, eastern Canada (~vicinity of 48º 47’ 32” North latitude, 58º 26’ 38” West longitude) Some info. from: Tony Peterson (pers. comm.) Geological Association of Canada/Mineralogical Association of Canada 1988 Field Trip Guidebook B8, day 1, stop 1. Suhr & Cawood (2001) - Geological Society of America Bulletin 113(8): 1025-1038.
Title: Chromitic serpentinite (Little Port Complex, Bay of Islands Ophiolite, Middle Cambrian, 505 Ma; Springer's Hill outcrop, Lewis Hills, Newfoundland) 4
Credit: https://www.flickr.com/photos/47445767@N05/50717822783/
Author: James St. John
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License: CC BY 2.0
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