Exhumation dynamics of high‑pressure metamorphic rocks from the Voltri Unit, Western Alps: constraints from phengite Rb–Sr geochronology
| Autor: | Paul G. Starr, Laura Federico, Andrew J. Smye, Marco Scambelluri, Spencer Mark Seman |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
geography
geography.geographical_feature_category 010504 meteorology & atmospheric sciences Subduction Metamorphic rock Bedrock Geochemistry Metamorphism engineering.material Eclogite · Subduction · Rb–Sr geochronology · Phengite · Exhumation · Alps 010502 geochemistry & geophysics 01 natural sciences Phengite Geophysics Geochemistry and Petrology Geochronology engineering Celadonite Eclogite Geology 0105 earth and related environmental sciences |
| Popis: | The Voltri Unit and adjacent Tertiary Piedmont Basin, Western Alps, preserve complementary bedrock and sedimentary archives of Alpine subduction and exhumation. Combined PT modeling and phengite Rb–Sr geochronology of bedrock and clast samples shows that Fe–Ti metagabbros and metasediments preserve a record of protracted high-pressure metamorphism, between ~ 50 and ~ 40 Ma. Bedrock and clast Fe–Ti metagabbros yield similar eclogite-facies peak conditions, between 23 and 25 kbar, 510–530 °C; phengite, zoned in celadonite content, with cores > 3.5 Si c.p.f.u. and rims 10 Myr until subduction ceased on arrival of the European continent into the orogenic wedge. As shear tractions on the plate interface are considered to exceed available buoyancy forces for exhumation, we suggest that syn-subduction exhumation occurred along the wedge-plate interface. |
| Databáze: | OpenAIRE |
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