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Pulverized quartz clasts in gouge of the Alhama de Murcia fault (Spain): Evidence for coseismic clast pulverization in a matrix deformed by frictional sliding

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Rodríguez Escudero, Emilio and Martínez Díaz, José J. and Giner Robles, Jorge L. and Tsige Aga, Meaza and Cuevas Rodríguez, Jaime (2020) Pulverized quartz clasts in gouge of the Alhama de Murcia fault (Spain): Evidence for coseismic clast pulverization in a matrix deformed by frictional sliding. Geology, 48 (3). pp. 283-287. ISSN 0091-7613, ESSN: 1943-2682

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Official URL: https://pubs.geoscienceworld.org/gsa/geology/article/48/3/283/579993/Pulverized-quartz-clasts-in-gouge-of-the-Alhama-de



Abstract

The fault gouge of the Alhama de Murcia fault (southeast Spain) shows a texture that resembles a mylonite, including a prominent foliation, S-C fabric, and isoclinal folds. It also embeds a large number of isolated pulverized quartz clasts (PQCs). Structural analysis indicates that the gouge fabric was mainly developed by slow frictional sliding along phyllosilicate-lined Riedel shear bands during continued shearing. In contrast, the PQCs show tensile fracture network features that are typically reported in seismically pulverized rocks found along seismogenic faults. This suggests that quartz-clast pulverization was due to a transient dilatational mechanism rather than shearing. We propose that the PQCs are the result of a rapid confined stress drop related to transient tensile stresses during coseismic ruptures that interrupt creep faulting along the gouge zone. The present study suggests that there is probably a large amount of evidence for paleoseismicity in fault rocks that is currently overlooked.


Item Type:Article
Uncontrolled Keywords:Betic Cordillera, Europe, faults, framework silicates, Iberian Peninsula, metamorphic rocks, quartz, schists, silica minerals, silicates, Southern Europe, Spain
Subjects:Sciences > Geology > Geodynamics
ID Code:60365
Deposited On:06 May 2020 10:18
Last Modified:06 May 2020 10:18

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