Fault rocks within the blueschist metabasalts of the Diamante–Terranova unit (southern Italy): potential fossil record of intermediate-depth subduction earthquakes
Abstract We report the first evidence of fault rocks (FRs) developed during high-pressure/low-temperature (HP/LT) subduction-related metamorphism, within quartz+epidote pods embedded in the glaucophane–lawsonite-bearing ophiolitic metabasalts of the Diamante–Terranova unit (Calabria, Italy). FRs occ...
Published in: | Geological Magazine |
---|---|
Main Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Cambridge University Press (CUP)
2019
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1017/s0016756819000062 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756819000062 |
id |
crcambridgeupr:10.1017/s0016756819000062 |
---|---|
record_format |
openpolar |
spelling |
crcambridgeupr:10.1017/s0016756819000062 2024-03-03T08:49:07+00:00 Fault rocks within the blueschist metabasalts of the Diamante–Terranova unit (southern Italy): potential fossil record of intermediate-depth subduction earthquakes Vitale, Stefano Fedele, Lorenzo Tramparulo, Francesco D’Assisi Prinzi, Ernesto Paolo 2019 http://dx.doi.org/10.1017/s0016756819000062 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756819000062 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Geological Magazine volume 156, issue 10, page 1771-1782 ISSN 0016-7568 1469-5081 Geology journal-article 2019 crcambridgeupr https://doi.org/10.1017/s0016756819000062 2024-02-08T08:39:00Z Abstract We report the first evidence of fault rocks (FRs) developed during high-pressure/low-temperature (HP/LT) subduction-related metamorphism, within quartz+epidote pods embedded in the glaucophane–lawsonite-bearing ophiolitic metabasalts of the Diamante–Terranova unit (Calabria, Italy). FRs occur as relic injections appearing as thin dark seams, locally showing an internal foliation characterized by tabular, curvilinear and meander-like shapes, and consist of very fine grains of glaucophane and titanite, locally including survivor clasts of epidote and lawsonite. Some boudinaged veins show glaucophane fibres in the boudin necks, marking a clear HP/LT syn-metamorphic origin at c . 30 km depth. The injected FRs can be alternatively interpreted either as pseudotachylytes or as fluidized ultracataclasites. Although subsequent recrystallization largely obliterated primary diagnostic features, the occurrence of (i) different-coloured flow streaks, characterized by alternating layers of glaucophane and titanite, (ii) well-developed flow folds and (iii) corroded epidote survivor crystals could indicate a viscous flow of molten material characterized by a non-uniform chemical composition. With this in mind, we support the hypothesis that these fine-grained veins were originally pseudotachylytes generated by the frictional melting of the glaucophane-rich layers of the Diamante–Terranova metabasalts, likely related to seismic events occurring during the Eocene along thrust faults within the subducting oceanic Ligurian lithosphere. The lack of evidence for pseudotachylyte relics in the metabasalt source rock argues for a selective preservation, largely dependent on the efficient mechanical shielding action of the stiffer quartz+epidote pods. Article in Journal/Newspaper Terranova Cambridge University Press Diamante ENVELOPE(-48.500,-48.500,-82.667,-82.667) Geological Magazine 156 10 1771 1782 |
institution |
Open Polar |
collection |
Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
topic |
Geology |
spellingShingle |
Geology Vitale, Stefano Fedele, Lorenzo Tramparulo, Francesco D’Assisi Prinzi, Ernesto Paolo Fault rocks within the blueschist metabasalts of the Diamante–Terranova unit (southern Italy): potential fossil record of intermediate-depth subduction earthquakes |
topic_facet |
Geology |
description |
Abstract We report the first evidence of fault rocks (FRs) developed during high-pressure/low-temperature (HP/LT) subduction-related metamorphism, within quartz+epidote pods embedded in the glaucophane–lawsonite-bearing ophiolitic metabasalts of the Diamante–Terranova unit (Calabria, Italy). FRs occur as relic injections appearing as thin dark seams, locally showing an internal foliation characterized by tabular, curvilinear and meander-like shapes, and consist of very fine grains of glaucophane and titanite, locally including survivor clasts of epidote and lawsonite. Some boudinaged veins show glaucophane fibres in the boudin necks, marking a clear HP/LT syn-metamorphic origin at c . 30 km depth. The injected FRs can be alternatively interpreted either as pseudotachylytes or as fluidized ultracataclasites. Although subsequent recrystallization largely obliterated primary diagnostic features, the occurrence of (i) different-coloured flow streaks, characterized by alternating layers of glaucophane and titanite, (ii) well-developed flow folds and (iii) corroded epidote survivor crystals could indicate a viscous flow of molten material characterized by a non-uniform chemical composition. With this in mind, we support the hypothesis that these fine-grained veins were originally pseudotachylytes generated by the frictional melting of the glaucophane-rich layers of the Diamante–Terranova metabasalts, likely related to seismic events occurring during the Eocene along thrust faults within the subducting oceanic Ligurian lithosphere. The lack of evidence for pseudotachylyte relics in the metabasalt source rock argues for a selective preservation, largely dependent on the efficient mechanical shielding action of the stiffer quartz+epidote pods. |
format |
Article in Journal/Newspaper |
author |
Vitale, Stefano Fedele, Lorenzo Tramparulo, Francesco D’Assisi Prinzi, Ernesto Paolo |
author_facet |
Vitale, Stefano Fedele, Lorenzo Tramparulo, Francesco D’Assisi Prinzi, Ernesto Paolo |
author_sort |
Vitale, Stefano |
title |
Fault rocks within the blueschist metabasalts of the Diamante–Terranova unit (southern Italy): potential fossil record of intermediate-depth subduction earthquakes |
title_short |
Fault rocks within the blueschist metabasalts of the Diamante–Terranova unit (southern Italy): potential fossil record of intermediate-depth subduction earthquakes |
title_full |
Fault rocks within the blueschist metabasalts of the Diamante–Terranova unit (southern Italy): potential fossil record of intermediate-depth subduction earthquakes |
title_fullStr |
Fault rocks within the blueschist metabasalts of the Diamante–Terranova unit (southern Italy): potential fossil record of intermediate-depth subduction earthquakes |
title_full_unstemmed |
Fault rocks within the blueschist metabasalts of the Diamante–Terranova unit (southern Italy): potential fossil record of intermediate-depth subduction earthquakes |
title_sort |
fault rocks within the blueschist metabasalts of the diamante–terranova unit (southern italy): potential fossil record of intermediate-depth subduction earthquakes |
publisher |
Cambridge University Press (CUP) |
publishDate |
2019 |
url |
http://dx.doi.org/10.1017/s0016756819000062 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756819000062 |
long_lat |
ENVELOPE(-48.500,-48.500,-82.667,-82.667) |
geographic |
Diamante |
geographic_facet |
Diamante |
genre |
Terranova |
genre_facet |
Terranova |
op_source |
Geological Magazine volume 156, issue 10, page 1771-1782 ISSN 0016-7568 1469-5081 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1017/s0016756819000062 |
container_title |
Geological Magazine |
container_volume |
156 |
container_issue |
10 |
container_start_page |
1771 |
op_container_end_page |
1782 |
_version_ |
1792506264084807680 |