Search results for "Collision zone"
showing 7 items of 7 documents
P and S wave travel time tomography of the SE Asia-Australia collision zone
2019
© 2019 Elsevier B.V. The southeast (SE)Asia - Australia collision zone is one of the most tectonically active and seismogenic regions in the world. Here, we present new 3-D P- and S-wave velocity models of the crust and upper mantle by applying regional earthquake travel-time tomography to global catalogue data. We first re-locate earthquakes provided by the standard ISC-Reviewed and ISC-EHB catalogues using a non-linear oct-tree scheme. A machine learning algorithm that clusters earthquakes depending on their spatiotemporal density was then applied to significantly improve the consistency of travel-time picks. We used the Fast Marching Tomography software package to retrieve 3-D velocity a…
Zircon ages of the Bayankhongor ophiolite mélange and associated rocks: Time constraints on Neoproterozoic to Cambrian accretionary and collisional o…
2010
Abstract Central Mongolia is geologically characterized by close juxtaposition of an accreted oceanic terrane with an arc-microcontinent collision zone. We present new U–Pb zircon ages and geochemical data for the Bayankhongor ophiolite melange from the oceanic terrane and for a syenite porphyry pluton from the arc-microcontinent zone, providing critical constraints on the regional evolution in late Neoproterozoic to early Cambrian times. An anorthosite (655 ± 4 Ma) associated with layered gabbro, a rodingite (metasomatized layered gabbro) (647 ± 6 Ma), and a high-level isotropic amphibole gabbro (647 ± 7 Ma) yielded the oldest zircon ages for the plutonic part of the ophiolite. A plagiogra…
Geochemical data and zircon ages for rocks in a high-pressure belt of Chu-Yili Mountains, southern Kazakhstan: Implications for the earliest stages o…
2011
Abstract The mechanism and age of Palaeozoic accretion in the Central Asian Orogenic Belt remain poorly constrained. One of the most complex belts extends from the Kokchetav area in northern Kazakhstan to the Kyrgyz northern Tianshan. It represents an assemblage of small blocks with Palaeoproterozoic continental crust, intervening slivers containing early Palaeozoic ophiolites and/or deep-marine sediments, and a number of HP and UHP metamorphic complexes. The HP–LT metamorphic rocks provide important clues for reconstructions of the overall structure and evolution of the accretionary collage. This study is aimed to constrain the metamorphic age and tectonic implications of HP garnet pyroxen…
Zircon dating of Neoproterozoic and Cambrian ophiolites in West Mongolia and implications for the timing of orogenic processes in the central part of…
2014
Abstract We present new isotopic and trace element data to review the geochronological/geochemical/geological evolution of the central part of the Central Asian Orogenic Belt (CAOB), and find a fundamental geological problem in West Mongolia, which has traditionally been subdivided into northwestern early Paleozoic (formerly Caledonian) and southerly late Paleozoic (formerly Hercynian) belts by the Main Mongolian Lineament (MML). We resolve this problem with SHRIMP zircon dating of ophiolites and re-evaluation of much published literature. In Northwest Mongolia the Dariv–Khantaishir ophiolite marks the boundary between the Lake arc in the west and the Dzabkhan–Baydrag microcontinent in the …
Quantifying the thermo-mechanical impact of plume arrival on continental break-up
2013
Abstract The arrival of a plume head at Earth's continental lithosphere is often considered to be an important factor for continental break-up. However, the impact of plume impingement on strength and duration of a rift remains unclear. In this study, we quantify the mechanical and thermal influence of a plume (i.e. lithosphere erosion) on continental break-up. To do that we apply the three-dimensional numerical code SLIM3D that features realistic elasto-visco-plastic rheology. We model the thermo-mechanical response of a segment of Earth's lithosphere that is affected both by extension as well as plume-related lithosphere erosion in order to evaluate the influence on the overall force budg…
Sapphire-bearing magmatic rocks trace the boundary between paleo-continents: A case study of Ilmenogorsky alkaline complex, Uralian collision zone of…
2021
Abstract Metamorphic gem corundum (mainly ruby) deposits are robust indicators of continent-continent collision processes. However, a systematic link of primary magmatic blue sapphire occurrences to orogenic belts is less understood. An example is the Ilmenogorsky alkaline complex, within the Ilmen Mountains region and part of the Uralian orogenic belt. The mobile belt is a product of the collision among Kazakhstania, Laurussia, and Siberia continents prior to the closure of the Paleo-Uralian ocean and formation of the Laurasia supercontinent (330–250 Ma). It is believed that the alkaline complex became inсluded into the separate Sysertsk-Ilmenogorsk microcontinent with unconstrained border…
Recycling plus: A new recipe for the formation of Alpine-Himalayan orogenic mantle lithosphere
2013
Abstract The origin of the lithospheric mantle beneath accretionary orogens is enigmatic; although severe compression of the buoyant crust occurs, the mantle lithosphere is generally thought to be removed and returned to the convecting mantle. We suggest that during the accretion of oceanic arcs and small continental blocks in the Mediterranean region, and more generally throughout the whole Alpine–Himalayan orogenic belt, the mantle lithosphere is newly created and composed of intimately mixed peridotite and crustal material from the forearc region. Potassium-rich volcanic rocks emplaced sometimes more than 30 Ma after the formation of this lithosphere carry evidence for the presence of ex…