Terrane

About: Terrane is a research topic. Over the lifetime, 11025 publications have been published within this topic receiving 442596 citations. The topic is also known as: tectonostratigraphic terrane.

Crustal-scale duplexing beneath the Yarlung Zangbo suture in the western Himalaya

Abstract: The fate of the Indian plate during continental collision with Asian terranes, and the proportion of the Indian crust that is underthrust or subducted beneath Tibet as opposed to transferred to the upper (Himalayan) plate, are much debated. The active geometry of low-angle underthrusting or subduction of the Indian plate beneath the Lesser and Greater Himalayan thrust sheets is well known from seismic imaging. Previously, only lower-resolution images of the Main Himalayan Thrust have been obtained beneath the Yarlung Zangbo suture that separates Indian and Asian rocks at the surface. It remains controversial whether the orogenic wedge between the Main Himalayan Thrust and the Yarlung Zangbo suture, formed of Indian crust transferred to the upper plate, is evolving by thrust-faulting in a critical-taper wedge or by southward extrusion of a ductile channel flow. Here we present a seismic reflection profile across the western Himalaya at 81.5° E, and show that the Main Himalayan Thrust dips ∼20° to ∼60 km depth beneath the Yarlung Zangbo suture, approaching a continuous Moho reflection at ∼70–75 km depth. The Indian crust being transported northwards beyond the Yarlung Zangbo suture is no more than ∼15 km thick, reduced from its original ∼40 km thickness by transfer of material from the lower plate to the upper plate through crustal-scale duplexing. The fate of the Indian plate during collision with Asia is debated. Seismic images of the western Himalaya reveal large-scale thrust faults that transfer Indian crust upwards, into the overriding Asian plate.

EUROBRIDGE: new insight into the geodynamic evolution of the East European Craton

Abstract: The Palaeoproterozoic crust and upper mantle in the region between the Ukrainian and Baltic shields of the East European Craton were built up finally during collision of the previously independent Fennoscandian and Sarmatian crustal segments at c. 1.8-1.7 Ga. EUROBRIDGE seismic profiling and geophysical modelling across the southwestern part of the Craton suggest that the Central Belarus Suture Zone is the junction between the two colliding segments. This junction is marked by strong deformation of the crust and the presence of a metamorphic core complex. At 1.80-1.74 Ga, major late to post-collisional extension and magmatism affected the part of Sarmatia adjoining the Central Belarus Zone and generated a high-velocity layer at the base of the crust. Other sutures separating terranes of different ages are found within Sarmatia and in the Polish-Lithuanian part of Fennoscandia. While Fennoscandia and Sarmatia were still a long distance apart, orogeny was dominantly accretionary. The accreted Palaeoproterozoic terranes in the Baltic-Belarus region of Fennoscandia are all younger than 2.0 Ga (2.0-1.9, 1.90-1.85 and 1.84-1.82 Ga), whereas those in Sarmatia have ages of c. 2.2-2.1 and 2.0-1.95 Ga. Lithospheric deformation and magmatism at c. 1.50-1.45 Ga, and Devonian rifting, are also defined by the EUROBRIDGE seismic and gravity models.

Geochronology and petrogenesis of granitic rocks in Gangdese batholith, southern Tibet

Abstract: Based on petrological and geochemical characteristics such as rock assemblage, petrogeochemistry, Sr-Nd isotope, zircon U-Pb age, and Hf isotope, we studied geochronological framework, magma types, source characters, and petrogenesis of different stages of magmatism of the granitic rocks from the Gangdese batholith in southern Tibet. The magmatic activities of the Gangdese batholith can be divided into three stages. The Mesozoic magmatism, induced by northern subduction of Neotethyan slab, was continuously developed, with two peak periods of Late Jurassic and Early Cretaceous. The Paleocene-Eocene magmatism was the most intensive, and resulted from a complex progress of Neotethyan oceanic slab, including subduction, rollback, and subsequent breakoff. And the Oligocene-Miocene magmatism was attributed to the convective removal of thickened lithosphere in an east-west extension setting after India-Asia collision. Isotopically, zircons from these granitic rocks are characterized by positive ɛ Hf(t) values, suggesting that the magmatic source of the Gangdese batholith might be an arc terrane, which was accreted to the southern margin of Asia during Late Paleozoic. Therefore, the chronological framework and Hf isotopic characteristics of the Gangdese batholith are distinct from the granitic rocks in adjacent areas, which can be served as a powerful tracer in studying source-to-sink relation of sediments during the uplift and erosion of Tibetan Plateau.

Proterozoic Lithospheric Evolution

Abstract: Recent years have seen significant new results on the evolution of Proterozoic terranes, and many of these resulted from new techniques, new concepts, and increasing multi-disciplinary research. In 1981, Working Group (WG) 3 of the International Lithosphere Program (ILP) was established. Its principal tasks were clarification of the origin and evolution of the Proterozoic rocks and of the magmatic, metamorphic, deformational processes involved in their evolution; elucidation of the basic patterns of the structure and composition of the Proterozoic lithosphere and their implicatin for the geochemical differentiation of mantle and crust and the growth of continents; and characterization of Proterozoic tectonic regimes and evaluation of the role of plate tectonics in Proterozoic orogenesis and lithospheric evolution.