one publication added to basket [77951] | Multistage hydrothermal alteration of gabbroic rocks from the failed Mathematician Ridge
In: Earth and Planetary Science Letters. Elsevier: Amsterdam. ISSN 0012-821X; e-ISSN 1385-013X, more
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Keywords |
Earth sciences > Geology > Lithology Metamorphism > Hydrothermal alteration Rocks > Igneous rocks > Gabbros ISE, Mathematician Ridge Marine/Coastal |
Abstract |
Oxygen isotopic, mineralogical and fluid inclusion data are presented for fresh and hydrothermally altered gabbroic rocks from the failed Mathematician Ridge. The Mathematician Ridge, though initially a fast-spreading ridge presently has a deep central rift valley more typical of slow-spreading rifts. The inner rift walls expose rare plutonic rocks uncomplicated by proximity to deep large-offset fracture zones. Undeformed Mathematician Ridge gabbros preserve most of the original texture and phase compositions and have been only slightly mineralogically or isotopically modified by post-crystallization hydrothermal alteration. Metagabbros have been subjected to a pervasive ductile deformation and recrystallization to foliated rocks composed of aluminous amphibole, low-calcium plagioclase and ilmenite. Oxygen isotope and phase chemical data suggest this event began at temperatures of up to 700 degree C, water-rock ratios of less than one, and produced modified seawater fluids with isotopic compositions of 3.5-6.0 ppt. |
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