TY - CHAP
T1 - In situ U-Pb zircon geochronology on metapelitic granulites of Beni Bousera (Betic-Rif system, N Morocco)
AU - Melchiorre, M.
AU - Álvarez-Valero, A. M.
AU - Vergés, J.
AU - Fernàndez, M.
AU - Belousova, E. A.
AU - El Maz, A.
AU - Moukadiri, A.
PY - 2017
Y1 - 2017
N2 - Integration of geochronological analyses of in situ zircons with the petrologi-cal study of their microstructural growth microdomains (through petrography and phase diagram modeling) yields a more precise interpretation and understanding of any geological process than the study of ages from separate zircons. This is essential especially for those rocks affected by polymetamorphic histories. We present new in situ U-Pb zircon dating from metapelitic granulites exposed in the contact with the ultramafic massif of Beni Bousera (northern Morocco, Western Mediterranean). Geo-chronological data scatter from Paleoproterozoic (1508 ± 23 Ma) to Miocene (22.9 ± 0.7 Ma), though the majority of ages range between 100 and 400 Ma, with four main peak ages clustering around 390-319, 286-264, 193, and 105 Ma. The Middle Permian (ca. 286-264 Ma) and earliest Miocene (22.9 ± 0.7 Ma) ages are constrained from a thermobarometric point of view: The former ages represent the formation of the zircons at depth (higher pressure), and the latter ages represent the exhumation process (lower pressure). Combining these petrological results with previous geophysical and geodynamical studies from the literature in the area, we propose a four-step geo-dynamic model for the Beni Bousera orogenic peridotite since the end of the Paleozoic (i.e., Middle Permian) to the present, supporting an evolution linked to a subduction-related scenario since Late Cretaceous times.
AB - Integration of geochronological analyses of in situ zircons with the petrologi-cal study of their microstructural growth microdomains (through petrography and phase diagram modeling) yields a more precise interpretation and understanding of any geological process than the study of ages from separate zircons. This is essential especially for those rocks affected by polymetamorphic histories. We present new in situ U-Pb zircon dating from metapelitic granulites exposed in the contact with the ultramafic massif of Beni Bousera (northern Morocco, Western Mediterranean). Geo-chronological data scatter from Paleoproterozoic (1508 ± 23 Ma) to Miocene (22.9 ± 0.7 Ma), though the majority of ages range between 100 and 400 Ma, with four main peak ages clustering around 390-319, 286-264, 193, and 105 Ma. The Middle Permian (ca. 286-264 Ma) and earliest Miocene (22.9 ± 0.7 Ma) ages are constrained from a thermobarometric point of view: The former ages represent the formation of the zircons at depth (higher pressure), and the latter ages represent the exhumation process (lower pressure). Combining these petrological results with previous geophysical and geodynamical studies from the literature in the area, we propose a four-step geo-dynamic model for the Beni Bousera orogenic peridotite since the end of the Paleozoic (i.e., Middle Permian) to the present, supporting an evolution linked to a subduction-related scenario since Late Cretaceous times.
UR - http://www.scopus.com/inward/record.url?scp=85021680120&partnerID=8YFLogxK
U2 - 10.1130/2017.2526(08)
DO - 10.1130/2017.2526(08)
M3 - Chapter
AN - SCOPUS:85021680120
SN - 9780813725260
T3 - The Geological Society of America special paper
SP - 151
EP - 171
BT - The crust-mantle and lithosphere-asthenosphere boundaries
A2 - Bianchini, Gianluca
A2 - Bodinier, Jean-Louis
A2 - Braga, Roberto
A2 - Wilson, Marjorie
PB - Geological Society of America
CY - Boulder, Colorado
ER -