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.

Geodynamic evolution of Central Asia in the Paleozoic and Mesozoic

Abstract: Central Asia is an ideal laboratory to study geodynamics and continental growth in the Phanerozoic (Sengor et al. 1993; Sengor and Natal’in 1996; Jahn et al. 2004; Xiao et al. 2004a, b; Kroner et al. 2007; Windley et al. 2007; Jian et al. 2008). Three important orogenic collages are exposed in Central Asia, i.e. the Altaids or Central Asian Orogenic Belt in the north, Tethysides in the south, and Western Pacific orogenic collages in the east. The architecture of Central Asia was mainly constructed from the interactions between these collages (Isozaki et al. 1990; Sengor et al. 1993; Yin and Nie 1996; Maruyama 1997; Xiao et al. 2008a, b). The interaction among these collages was the major topic of a 5-day thematic workshop on ‘‘Geodynamic Evolution of Central Asia in the Paleozoic and Mesozoic’’, held in Beijing, China, in December 2006 and funded by the SinoGerman Centre for Research Promotion (Chinesisch-Deutsches Zentrum fur Wissenschaftsforderung) (Xiao and Kroner 2007). The workshop was attended by more than 50 participants representing eight countries (Germany, UK, France, Russia, Australia, Italy, Cuba, and China) and was co-sponsored jointly by Task Force I (Earth Accretionary Systems) of the International Lithosphere Program (ILP), IGCP Project 480, and the State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences (CAS). The current thematic volume arises from this workshop and also includes several invited contributions. The 18 papers in this volume reflect a relatively broad spectrum of current research and cover regions in the southern Altaids as well as the northern Tethysides and the Japan Islands where the Altaids and Tethysides possibly join (Fig. 1). Wenjiao Xiao and co-authors (this volume) synthesize accretionary processes during final terrane amalgamation in the Altai and Tien Shan Mountain Range of NW China and Inner Mongolia in the late Permian to mid-Triassic. They use structural, geochemical, geochronological and palaeomagnetic data to show that there was continuous southward accretion in the late Paleozoic to middle Triassic of volcanic arcs, accretionary wedges and HPto UHPmetamorphic rocks. Final closure of the Paleoasian Ocean led to docking of the Tarim and North China Cratons with the amalgamated CAOB terrranes and terminal orogenesis. This complex geodynamic evolution led to formation of major metal deposits and substantial crustal growth. Jun Gao and co-authors (this volume) provide geochemical data and zircon ages for metaluminous to weakly peraluminous granitoids in the southern Chinese Tianshan and relate these to continental arc settings between ca. 480 and 275 Ma ago. These authors favor Silurian to Carboniferous northward subduction of the South Tianshan oceanic plate beneath the southern margin of the Central Tianshan-Kazakhstan-Yili continental plate and argue for W. Xiao (&) State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China e-mail: wj-xiao@mail.igcas.ac.cn

Accreted Terranes in the Northern Part of the Philippine Archipelago

Abstract: The Philippine Archipelago consists of a complex array of ophiolites, continental fragments and island arc elements that can be identified as accreted terranes, similar to those increasingly recognized as components of orogenic zones. The northern Philippines, including Luzon, Mindoro and nearby smaller islands, can be divided into at least six of these tectonic elements. From west to east across central Luzon there are the Neogene accretionary prism of the West Luzon Arc, the Eocene Zambales ophiolite, the Cretaceous Angat ophiolite, and a late Cretaceous-early Paleogene volcanic arc built on an older metamorphic basement. This arc terrane is repeated by offset along the Philippine Fault. To the south, the western Luzon terranes are juxtaposed against the metamorphic basement block of Mindoro, which itself is colliding with the North Palawan microcontinental fragment. The ophiolites appear to have originated in back arc basins rather than in oceanic plateaus, and the metamorphic belts have protoliths indicating deformation along active margins, perhaps deep within accretionary prisms. The Philippine terranes are interpreted as fragments that originated within the complex Pacific-Eurasian plate boundary rather than as intra-Pacific basin units. These terranes have been assembling at least since the Oligocene by strike-slip and convergent displacements. Strike-slip displacement, either along transcurrent faults or as a component of convergence played a very important, if not dominant, role in this assembly. Most terranes identified in the northern Philippine appear to be plate fragments, with attached crust and upper mantle. Their characteristics contrast with those usually interpreted for terranes in the North American Cordillera, where near-orthogonal convergence and shallow dipping terrane sutures are favored.

Rifting of the South China Sea: new perspectives

Abstract: The Cenozoic evolution of SE Asia records a diverse array of tectonic processes with rifting, subduction, terrane collision and large-scale continental strike-slip faulting occurring in spatially and temporally complex relations. Oligocene seafloor spreading and rift propagation in the South China Sea are critical tectonic events that overprint an earlier phase of regional extension. Two end-member models proposed to explain the opening of the South China Sea differ in the relative importance of extrusion versus subduction as the driving mechanism. This paper treats the South China Sea region as a large multi-phase continental rift basin. Synthesizing recently published studies and using filtered Bouguer gravity data, we make a series of observations and possible interpretations to advance the notion that a hybrid tectonic models need to be proposed and tested. We present an example from the Phu Khanh Basin where flexural backstripping supports our interpretation that an ‘out-of-sequence’ rifting event was of sufficient magnitude to completely attenuate the continental crust in the ultra deep water part of the basin. The complex rift history of the region leads us to believe that future frontier hydrocarbon exploration will carry large uncertainties from basin to basin.

Overview of the COCORP 40°N Transect, western United States: The fabric of an orogenic belt

Abstract: The COCORP 40°N Transect of the Cordillera of the western United States crosses tectonic features ranging in age from Proterozoic to Recent and provides an acoustic cross-section of a complex orogen affected by extension, compression, magmatism, and terrane accretion. The key features of the transect, centered on the Basin and Range Province, include (1) asymmetric seismic fabrics in the Basin and Range, including west-dipping reflections in the eastern part of the province and predominantly subhorizontal ones in the west; (2) a pronounced reflection Moho at 30 ± 2 km and locally as deep as 34 km in the Basin and Range with no clear sub-Mono reflections; and (3) complex-dipping reflections and diffractions locally as deep as 48 km in the Colorado Plateau and Sierra Nevada. The eastern part of the transect, shot above known and inferred Precambrian crystalline basement, probably records features related to the entire history of the orogen, locally perhaps as old as 1800 Ma. In this region, major paleotectonic features probably controlled subsequent structural development. In title western half of the transect, however, most reflectors are probably no older than Mesozoic. Within the Basin and Range Province, there appears to be a strong Cenozoic overprint that is characterized by asymmetric half-grabens, low-angle normal faults, and a pervasive subhorizontal system of reflections in the lower crust; no one model of intracontinental extension is universally applicable. Processes that produce or are accompanied by thermal anomalies (magmatism, enhanced ductility, and extension) appear to be essential in developing a highly layered lower crust.