Early Cretaceous tectonics across the North Pacific: New insights from multiphase tectonic extension in Eastern Eurasia

Abstract Late Variscan magmatism in the Iberian Chain (Central Spain) is recorded by the presence of both pyroclastic units and high-level intrusions (sills and dykes). This magmatism encompasses a variety of subalkaline igneous rocks, from basalt to rhyolite; andesitic rocks are, however, dominant. The pyroclastic units contain plant fossils and pollen that suggest an Autunian age, which is consistent with the available K-Ar radiometric age data (283–292 Ma) obtained for the hypabyssal intrusions. Earlier amphibole-rich andesite, rich in crustal xenoliths (metapelite, granitoid and quartzite fragments) and xenocrysts (e.g. garnet) suggest the occurrence of significant crustal assimilation in the petrogenesis of the intermediate magmas, whereas later intrusions (pyroxene-rich andesites, basalts and some rhyolites) lack any crustal xenoliths or xenocrysts. Crustal assimilation is also suggested by the radiogenic 87 Sr/ 86 Sr 290 and negative ɛNd 290 values for all the studied rocks. The cross-cutting relationships between the different rock types provide evidence for a multi-stage magmatic evolution, coeval with the post-orogenic transtensive evolution of the southern Variscan belt in Europe. A significant hiatus, covering the Middle Permian and most of the Upper Permian, separates this Lower Permian magmatism from the subsequent Triassic and Jurassic alkaline magmatism that represents different rifting events that affected the Iberian Chain, progressively thinning the Variscan crust as the Alpine cycle began.

Extensional tectonics

10.1144/gsl.sp.2004.223.01.20

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Citations (38)

Geosynkline, Orogeny and Plate Tectonics

Zeitschrift der Deutschen Geologischen Gesellschaft (1976)

John G. Dennis

Orogeny

10.1127/zdgg/127/1976/73

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Citations (0)

Tectono-Convective Modes on Earth and Other Terrestrial Bodies

Elsevier eBooks (2023)

P. J. Tackley

geodynamics

10.1016/b978-0-323-85733-8.00006-8

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Citations (5)

Tektonika utworów kambryjskich obszaru świetokrzyskiego

Przegląd Geologiczny (1992)

Włodzimierz Mizerski

TECTONICS OF THE CAMBRIAN SEQUENCE IN THE HOLY CROSS MOUNTAINS Summary The 100 years history of the Cambrian System in the Holy Cross Mountains is a good example of changes not only in stratigraphy but in the tectonic too. The tectonic of the Cambrian deposits in the northen part of the Holy Cross Mountains is better documented (J. Czarnocki 1950, W. Mizerski 1979, 1991) than the southern one. The Cambrian deposits from both parts of Holy Cross Mountains are different in age and in the scale of tectonic deformations. Cambrian rocks in the northern part are incorporated into Variscian tectonic unit (Fig. 1), which was established by orogeny during the Carboniferous. Cambrian rocks are now visible inside the block structures with tectonic deformations resulted from disharmonic folding. It is possible to recognize some stages during the Variscian orogeny and variable tectonic mesostructures are joined with these stages. The Cambrian deposits in the southern part of the Holy Cross Mountains are incorporated into the Early Caledonian tectonic unit (Fig. 2). These rocks were deformed tectonically during the Sandomirian, Early Caledonian and Variscian orogenies. The intensity of the mentioned tectonic activities is different in time and space on this area. The last stage of tectonic activity on this area is the Laramic phase of the Alpine orogeny (at the boundary of the Cretaceous-Tertiary) and the effects of this phase are visible in the Cambrian rocks of the south-western part of studied area. This centenary is a good opportunity to present directions of the tectonic researches in the future.

Orogeny

Tectonic phase

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K-T magmatism of western Rajasthan, India: Manifestation of Reunion plume activity or extensional lithospheric tectonics?

AGU Fall Meeting Abstracts (2004)

Kamal Kant Sharma

Extensional tectonics

Mantle plume

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