Exhumation Processes Research Articles

Timing of collision of the Sino-Korean and Yangtse cratons: U-Pb zircon dating of coesite-bearing eclogites

Research Article| April 01, 1993 Timing of collision of the Sino-Korean and Yangtse cratons: U-Pb zircon dating of coesite-bearing eclogites Leslie Ames; Leslie Ames 1Department of Geological Sciences, University of California, Santa Barbara, California 93106 Search for other works by this author on: GSW Google Scholar George R. Tilton; George R. Tilton 1Department of Geological Sciences, University of California, Santa Barbara, California 93106 Search for other works by this author on: GSW Google Scholar Gaozhi Zhou Gaozhi Zhou 2Hubei Institute of Regional Geology and Mineral Resources, Wuhan, Hubei, China Search for other works by this author on: GSW Google Scholar Geology (1993) 21 (4): 339–342. https://doi.org/10.1130/0091-7613(1993)021<0339:TOCOTS>2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Leslie Ames, George R. Tilton, Gaozhi Zhou; Timing of collision of the Sino-Korean and Yangtse cratons: U-Pb zircon dating of coesite-bearing eclogites. Geology 1993;; 21 (4): 339–342. doi: https://doi.org/10.1130/0091-7613(1993)021<0339:TOCOTS>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The suture zone between the Sino-Korean and Yangtse cratons in central China is marked by a series of fault-bounded belts composed of crustal protoliths. In the Dabie Mountains some of these blocks contain coesite and diamond, indicating subduction to minimum depths of ∼120 km as a result of continental collision. The blocks range from the structurally lowest ultrahigh-pressure metamorphic belt and decrease in metamorphic grade upsection to the structurally highest, low greenschist facies belt. Furthermore, the faults mark large contrasts in metamorphic grade. These features form a structure that is similar to metamorphic core complexes, indicating extension as part of the exhumation process. Timing of the continental collision has previously been inferred as Late Triassic, from regional geologic relations, or Caledonian, from 40Ar/39Ar dating of the adjacent and possibly related Qinling metamorphic belt. U-Pb dating of zircon from ultra-high-pressure eclogites yields a metamorphic age of 209 ±2 Ma. This age coincides with later stages of collision and is therefore a minimum estimate of the time of collision. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Pressure--Temperature--Time Paths of Regional Metamorphism I. Heat Transfer during the Evolution of Regions of Thickened Continental Crust

The development of regional metamorphism in areas of thickened continental crust is investigated in terms of the major controls on regional-scale thermal regimes. These are: the total radiogenic heat supply within the thickened crust, the supply of heat from the mantle, the thermal conductivity of the medium and the length and time scales of erosion of the continental crust. The orogenic episode is regarded as consisting of a relatively rapid phase of crustal thickening, during which little temperature change occurs in individual rocks, followed by a lengthier phase of erosion, at the end of which the crust is at its original thickness. The principal features of pressure-temperature-time (PTt) paths followed by rocks in this environment are a period of thermal relaxation, during which the temperature rises towards the higher geotherm that would be supported by the thickened crust, followed by a period of cooling as the rock approaches the cold land surface. The temperature increase that occurs is governed by the degree of thickening of the crust, its conductivity and the time that elapses before the rock is exhumed sufficiently to be affected by the proximity of the cold upper boundary. For much of the parameter range considered, the heating phase encompasses a considerable portion of the exhumation (decompression) part of the PTt path. In addition to the detailed calculation of PTt paths we present an idealized model of the thickening and exhumation process, which may be used to make simple calculations of the amount of heating to be expected during a given thickening and exhumation episode and of the depth at which a rock will start to cool on its ascent path. An important feature of these PTt paths is that most of them lie within 50 °C of the maximum temperature attained for one third or more of the total duration of their burial and uplift, and for a geologically plausible range of erosion rates the rocks do not begin to cool until they have completed 20 to 40 per cent of the total uplift they experience. Considerable melting of the continental crust is a likely consequence of thickening of crust with an average continental geotherm. A companion paper discusses these results in the context of attempts to use metamorphic petrology data to give information on tectonic processes. © 1984 Oxford University Press.

Early Cretaceous metamorphic age of the South Fork Mountain Schist in the northern Coast Ranges of California

Ductile deformation and mass loss in the Franciscan Subduction Complex: implications for exhumation processes in accretionary wedges

Pre-deccan trap topography in central India and crustal warping in relation to Narmada rift structure and volcanic activity

A study of the geology of the Dhar Forest, the Pachmarhi plateau and the area around Bari in Central India has led to the conclusion that the pre-Deccan Trap topography which was completely covered by the lava flows and is being exposed with spectacular clarity by the process of exhumation, had much the same relief as the present land surface. The geomorphological studies of the Vindhyan and Pachmarhi plateau suggest a characteristic rise and increasing separation of different planation surfaces towards the edges of the Narmada rift valley and indicate upwarping movements in several distinct stages.