scholarly journals Strong Lg-wave attenuation in the Middle East continental collision orogenic belt

2016 ◽  
Vol 674 ◽  
pp. 135-146 ◽  
Author(s):  
Lian-Feng Zhao ◽  
Xiao-Bi Xie
Keyword(s):  
Middle East ◽  
Wave Attenuation ◽  
Continental Collision ◽  
Orogenic Belt ◽  
Lg Wave

Collision and reactivation along the South Tianshan Orogen (NW China) through late Paleozoic to Mesozoic time

2021 ◽  
Author(s):  
Yigui Han ◽  
Guochun Zhao
Keyword(s):  
Continental Collision ◽  
Orogenic Belt ◽  
Late Paleozoic ◽  
Magma Source ◽  
The South ◽  
Nw China ◽  
Magmatic Rocks ◽  
Western Tianshan ◽  
Tarim Craton ◽  
South Tianshan

<p>The South Tianshan Orogenic Belt in NW China marks the suturing site between the Tarim Craton and the Central Asian Orogenic Belt (CAOB) during late Paleozoic-Mesozoic time. Despite numerous investigations, the amalgamation history along the South Tianshan Orogen remains controversial, especially on the timing and process of the final continental collision between the Tarim Craton and the Central Tianshan (CTS)-Yili Block. We inquire into this issue on the basis of a compiled dataset across the Tarim, South Tianshan and CTS-Yili regions, comprising elemental and isotopic data of magmatic rocks and radiometric ages of regional magmatism, detrital zircons, (ultra-)high pressure metamorphism and tectonothermal events. The data support a continental collision along the South Tianshan belt in 310-300 Ma, in accord with a contemporaneous magmatic quiescence and a prominent decrease of εNd(t) and εHf(t) values of magmatic rocks in the CTS region, and a main exhumation stage of (U)HP rocks in the South Tianshan region. The collisional orogeny along the South Tianshan have most likely been influenced by a mantle plume initiated at ca. 300 Ma underneath the northern Tarim Craton, as evidenced by temporal and spatial variations of geochemical proxies tracing magma source characteristics. The new model of plume-modified collision orogeny reconciles the absence of continental-type (U)HP rocks in the orogen and the insignificant upper-plate uplift during continental collision. In the mid-Triassic (ca. 240 Ma), the Chinese western Tianshan underwent intense surface uplift and denudation, as indicated by sedimentary provenance analysis and tectonothermal events. Paleocurrent and detrital zircon age data from Triassic strata in northern Tarim suggest a provenance change from a single source of the Tarim Craton to multiple sources including the CTS-Yili Block to the north and the Western Kunlun Orogen to the south. We suggest that the mid-Triassic uplifting in Chinese western Tianshan was an intracontinental orogeny caused by far-field effects of the collision between the Tarim Craton and the Qiangtang Block. This research was financially supported by NSFC Projects (41730213, 42072264, 41902229, 41972237) and Hong Kong RGC GRF (17307918).</p>

Lg Wave Attenuation in the Isparta Angle and Anatolian Plateau (Turkey)

2012 ◽  
Vol 170 (3) ◽  
pp. 337-351 ◽  
Author(s):  
Sakir Sahin ◽  
Xueyang Bao ◽  
Niyazi Turkelli ◽  
Eric Sandvol ◽  
Ugur Teoman ◽  
...  
Keyword(s):  
Wave Attenuation ◽  
Anatolian Plateau ◽  
Isparta Angle ◽  
Lg Wave

Sapphire-bearing magmatic rocks as indicators of the continental collision tectonic events: a case study of Uralian orogenic belt

2021 ◽  
Author(s):  
Elena Sorokina ◽  
Roman Botcharnikov ◽  
Yuriy Kostitsyn ◽  
Delia Rösel ◽  
Tobias Häger ◽  
...  
Keyword(s):  
Continental Collision ◽  
Orogenic Belt ◽  
Tectonic Activity ◽  
Alkaline Complex ◽  
Important Indicator ◽  
Tectonic Events ◽  
Magmatic Rocks ◽  
Orogenic Belts

<p>Gem corundum (mainly ruby) occurrences are commonly associated with orogenic belts. Corundum deposits of metamorphic origin are known as robust indicators of continent-continent collision tectonic events. Although sapphire-bearing primary magmatic deposits are also found in orogenic belts, their link to continental collision process remains poorly understood. Here we show that primary igneous blue sapphire occurrences in the Ilmenogorsky alkaline complex of Ilmen Mountains in Uralian orogenic belt are indicative of the continent-continent collision processes among Kazakhstania, Laurussia, and Siberia 330 – 250 Ma ago (Sorokina et al. 2017).</p><p>The results of geochemical, mineralogical, and geochronological research of corundum syenite pegmatites demonstrate that <em>in situ</em> primary magmatic corundum-bearing mineral assemblages can be used to evaluate the formation conditions and the time constraints of magmatic processes imposed by tectonic activity during orogenesis.</p><p>Thus, the corundum syenite pegmatites have recorded a multistage evolution of the Ilmenogorsky complex. They crystallized at temperatures of 700 – 750°C at 275 and 295 Ma ago (<em>in situ</em> LA-ICP-MS U-Pb zircon dating) within the timeframe of the continental collision of the Uralian orogeny. The isotopic signatures show a geochemical link of these deposits to nepheline syenites – miaskites of the main igneous body in Ilmenogorsky complex. While, some corundum syenite-pegmatites express the metamorphic overprint at temperatures of 700 – 780°C occurred 249 ± 2Ma ago (TISM Rb-Sr isotopy) during limited post-collision stretching period in the area of Ilmenogorsky complex (Sorokina et al. 2021). Hence, these results imply that primary magmatic corundum deposits can be used as an important indicator of continental collision events.</p><p>References:</p><div> <p>1.              Sorokina E.S., Botcharnikov R., Kostitsyn Yu.A., Rösel D., Häger T., Rassomakhin M.A., Kononkova N.N., Somsikova A.V., Berndt J., Ludwig T., Medvedeva E.V., Hofmeister W. (2021). Sapphire-bearing magmatic rocks trace the boundary between paleo-continents: a case study of Ilmenogorsky alkaline complex, Uralian collision zone of Russia. Gondwana research 2021 (in press).</p> <p>2.  Sorokina, E.S., Karampelas, S., Nishanbaev, T.P., Nikandrov, S.N., Semiannikov, B.S., (2017). Sapphire Megacrysts in Syenite Pegmatites from the Ilmen Mountains, South Urals, Russia: New Mineralogical Data. Canadian Mineralogist 55, 823–843</p> </div>

Tectonic accretion and recycling of the continental lithosphere during the Alpine orogeny along the Pyrenees

2014 ◽  
Vol 185 (4) ◽  
pp. 257-277 ◽  
Author(s):  
Olivier Vanderhaeghe ◽  
Alexia Grabkowiak
Keyword(s):  
Lithospheric Mantle ◽  
Plate Boundary ◽  
Thermal Relaxation ◽  
Continental Collision ◽  
Orogenic Belt ◽  
Mountain Range ◽  
Continental Lithosphere ◽  
Calculated Volume ◽  
Ductile Flow ◽  
The Difference

Abstract The goal of this paper is to identify the fate of the continental lithosphere along the Iberia-Eurasia convergent plate boundary marked by the formation of the Pyrenean orogenic belt. The present-day volumes of crust and lithosphere beneath the Pyrenees and the volume of eroded crust redistributed in neighbo ring basins are evaluated based on a synthesis of available geological and geophysical data. The volumes that are expected to have transited across the former plate boundary are modeled taking into account Iberia-Eurasia convergence and making assumptions regarding the initial lithospheric and crustal structure of the Iberia-Eurasia plate boundary at the onset of continental collision (~83 Ma). Despite large uncertainties, the difference between the initial and present-day lithospheric structures suggests that at 83 Ma, either the Iberia-Eurasia plate boundary was marked by a zone of thinned lithosphere (oceanic and/or continental), or the lithosphere having transited across the plate boundary has for the most part been recycled into the mantle. At the crustal-scale, the volume of tectonically accreted crust is estimated by adding the volume of crust currently present in the Pyrenean orogenic belt to the volume of sediments deposited in neighboring basins, and by subtracting the initial volume of crust at the onset of continental collision considering two end-members, namely (i) a continental rift or (ii) a 35 km wide oceanic basin. In both cases, this tectonically accreted crustal volume is not enough to match the calculated volume of crust that has potentially transited across the plate boundary as a consequence of convergence since 83 Ma. As a result, our computation suggests that at least 30% (and as much as 63%) of the continental crust has subducted with the Iberian lithospheric slab and has been recycled into the mantle. In addition, the synthesis of topographic and geophysical (gravity and seismic tomography) reveals a peculiar crustal and lithospheric scale structure for the current day Pyrenees characterized by (i) an elliptical-cone-shape Pyrenean mountain range underlain by an elliptical-cone-shaped crustal root pointing down, and (ii) two tongues of lithospheric mantle in the central part of the belt. These features are interpreted as reflecting redistribution of the lithospheric mantle and of the orogenic crust by ductile flow after subduction and tectonic accretion. We propose that following a period of subduction/collision from 83 to 35 Ma, the decrease in the convergence rate between Iberia-Eurasia favored thermal relaxation of the Iberian slab promoting ductile flow and the development of gravitational instabilities. We suggest that the orogenic root has been dragged down by the dense lithospheric root and that part of it has been recycled into the mantle. In this view, the current-day lithospheric tongues represent the remnants of the lithospheric root after thermal relaxation and recycling by convective removal.

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