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.

The Svecofennian orogen: a collage of microcontinents and island arcs

Abstract: Based on an integrated study of geological and geophysical data, a tectonic model for the Palaeoproterozoic evolution of the Svecofennian orogen within the Fennoscandian Shield at the northwestern corner of the East European Craton is proposed. The Svecofennian orogen is suggested to have formed during five, partly overlapping, orogenies: Lapland-Savo, Lapland-Kola, Fennian, Nordic and Svecobaltic. The Svecofennian orogen evolved in four major stages, involving microcontinent accretion (1.92-1.88 Ga), large-scale extension of the accreted crust (1.87-1.84 Ga), continent-continent collision (1.87-1.79 Ga) and finally gravitational collapse (1.79 and 1.77 Ga). The stages partly overlapped in time and space, as different processes operated simultaneously in different parts of the plates. In the Lapland-Savo and Fennian orogenies, microcontinents (suspect terranes) and island arcs were accreted to the Karelian microcontinent, which itself was accreting to Laurentia in the Lapland-Kola orogeny. The formation of the Svecofennian orogen was finalized in two continental collisions producing the Nordic orogen in the west (Fennoscandia-Amazonia) and Svecobaltic orogen in the SSW (Fennoscandia- Sarmatia). The collisions were immediately followed by gravitational collapse.

Zircon Hf isotopic constraints on the sources of the Indus Molasse, Ladakh Himalaya, India

Abstract: [1] India-Asia collision has resulted in the largest orogenic event on Earth since at least 500 Ma, and this has had a profound influence on the drainage patterns of Asia, on the Asian monsoon climate, on global oceanography, as well as on faunal extinctions. Despite this importance, understanding of the Paleogene evolution of this system is limited. U-Pb and Lu-Hf isotopic analyses of detrital zircons from the clastic sedimentary rocks of the Indus Molasse, located within the Indus Suture of the Ladakh Himalaya, India, show that most have Mesozoic-Cenozoic ages and juvenile Hf isotopic compositions. This suggests that the main source of these sediments is the Transhimalayan batholith, with minor flux from the Lhasa-Karakoram terrane and Indian plate. The lower Indus Molasse ( Chogdo Formation) is inferred to have been deposited at 60 - 49 Ma, whereas the upper Choksti Formation was deposited later than 45-41 Ma and contains a greater contribution from the Lhasa terrane. The Transhimalayan batholith was eroded throughout Indus Molasse sedimentation, but increasing exhumation of Lhasa-Karakoram terrane indicates its progressive uplift after initial collision, and requires formation of apaleo-Indus River shortly after collision.