Computer Science
Scientific paper
Mar 1996
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996e%26psl.139..223a&link_type=abstract
Earth and Planetary Science Letters, vol. 139, Issue 1-2, pp.223-238
Computer Science
11
HolsnØ, Y Island Norway, Garnet Group, Pseudotachylyte, Lower Crust, Earthquakes, Deformation, Elsevier: Holsnøy Island Norway, Garnet Group, Pseudotachylyte, Lower Crust, Earthquakes, Deformation
Scientific paper
Syn-eclogite facies pseudotachylytes of the Bergen Arcs, western Norway, were formed during co-seismic faulting at a depth of 60 km during Caledonian continent collision, concurrent with fluid-induced partial eclogitization of Precambrian anorthositic granulites. The pseudotachylytes contain the high-pressure assemblage omphacite, garnet and kyanite and formed in the metastable granulites at the border of eclogitized areas. Rock volumes corresponding to outcrops of 100 m 2 in area were shattered by pseudotachylytes associated with ultramylonites, cataclasites and shear zones. The granulite facies garnets, unzoned and inclusion-free away from the pseudotachylyte veins, display planar and curved fractures, brecciation and melting with decreasing distance from the veins. Sieve-textured garnet developed by the disintegration of granulite facies garnet, crystallization of eclogite facies mineral inclusions and welding together of garnet fragments. Fractured granulite facies garnets trend to more almandine-rich compositions, with variable grossular contents. In the pseudotachylyte veins, a second generation of minute (10-200 m) euhedral or dendritic garnets has a higher ratio than the granulite facies garnet and a wide range in grossular content (Grs 11 -Grs 89 ), suggesting rapid growth and cooling. Fracturing of garnet and its preferential disappearance in the pseudotachylyte show that garnet has a relatively low fracture toughness. Seismic faulting caused enhanced reaction rates during ongoing fluid-induced eclogitization of the deep crust by increasing the surface to volume ratio of garnet and its dislocation density. The sudden volume reduction associated with eclogitization of metastable crust may have nucleated further faulting and pseudotachylyte formation.
Austrheim Håkon
Boundy Theresa M.
Erambert Muriel
No associations
LandOfFree
Garnets recording deep crustal earthquakes does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Garnets recording deep crustal earthquakes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Garnets recording deep crustal earthquakes will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1645833