Paper No. 10-2
Presentation Time: 1:55 PM
A COMPARISON AMONG THE MEGUMA TERRANE OF EASTERN CANADA, THE SEHOUL BLOCK OF NW AFRICA, THE HARLECH DOME OF NORTH WALES, AND THE SOUTH PORTUGUESE ZONE OF SOUTHERN SPAIN AND PORTUGAL
KUIPER, Yvette D.1, BARR, Sandra M.2, WALDRON, John3, WHITE, Chris E.2, GERMAIN, Rémi4, HAISSEN, Faouziya5, EL HASSANI, Ahmed6, SAÏD, Belkacim7, MARTÍNEZ, David8, ACCOTTO, Cristina9 and MONTERO, Pilar10, (1)Department of Geology and Geological Engineering, Colorado School of Mines, 1516 Illinois Street, Golden, CO 80401, (2)Earth and Environmental Science, Acadia University, Wolfville, NS B4P 2R6, Canada, (3)Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB T6G2E3, Canada, (4)Department of Civil and Environmental Engineering, Colorado School of Mines, 1516 Illinois Street, Golden, CO 80401, (5)Hassan II University of Casablanca, Casablanca, Morocco, (6)Académie Hassan des Sciences et Techniques, Rabat, Morocco, (7)Département de Géologie, Université Ibn Zohr, B.P 8106, Cité Dakhla, Agadir, QC 80 000, Morocco, (8)Department of Geodynamics, University of Granada, Facultad de Ciencias, Campus Fuentenueva, Avenida Fuentenueva s/n, Granada, 18071, Spain, (9)Départment de Géologie et Génie Géologique, Université Laval, Québec, QC G1V 0A6, Canada, (10)Department of Mineralogy and Petrology, University of Granada, Facultad de Ciencias, Campus Fuentenueva, Avenida Fuentenueva s/n, Granada, 18002, Spain
The Meguma terrane of Canada, the Harlech Dome of Wales, the Sehoul Block of NW Africa, and the South Portuguese Zone of Iberia have previously been interpreted as part of a larger Gondwanan domain Megumia. We compare their characteristics based on published data. The Meguma terrane consists of primarily latest Ediacaran to Early Ordovician turbiditic metasandstone and slate, locally overlain by early Silurian to Early Devonian slate, quartzite and metavolcanic rocks. The Cambrian to Tremadocian rocks are similar to those of the Harlech Dome, but their post-Tremadocian histories diverge. In the Meguma terrane, Early to Middle Devonian greenschist to amphibolite facies metamorphism and folding were followed by mainly Late Devonian peraluminous granitic plutonism. The detrital zircon in various units of the Meguma terrane has a strong West African signature with large ~2.2–1.9 Ga and ~700–500 Ma populations, and minor ~1.5–0.9 Ga dates. Based on drill core data, the Meguma terrane extends offshore to the southeast.
The Sehoul Block primarily consists of Cambrian phyllite and metawacke. It was folded and metamorphosed prior to intrusion of the peraluminous 367±9 Ma Rabat granite. The Meseta domain to the south does not show the same deformation, metamorphism and plutonism, implying that the Sehoul Block was separated from NW Africa during that time. The Sehoul Block was juxtaposed with the Meseta domain in the Carboniferous along the Sehoul thrust. Detrital zircon of the Sehoul Block is dominated by 605–560 Ma ages with a smaller ~2.0 Ga population, and a few ~1.0 Ga grains.
The South Portuguese Zone consists of Middle Devonian (and older?) to Carboniferous metasedimentary and metavolcanic rocks. Detrital zircon shows a large 630–580 Ma population, with a smaller ~2.2–1.9 Ga population. Some of the rocks also show a significant Mesoproterozoic population, which has been interpreted as indicating an Avalonian origin. A 375–365 Ma population corresponds with ages of granites in the Meguma terrane and the Sehoul Block. By the Middle Devonian, the South Portuguese Zone may have been in proximity to, and derived zircon from Avalonia and/or elements of Megumia, but the origin of its basement remains unclear. We conclude that the Harlech Dome and Sehoul Block show similarities to the Meguma terrane, starting in the Cambrian.
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