부산대학교 도서관

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.tecto.2007.11.052 Byline: Thomas K. Kelty (a), An Yin (b)(c)(d), Batulzii Dash (e), George E. Gehrels (f), Angela E. Ribeiro (a) Keywords: Mongol-Okhotsk Ocean; Hangay-Hentey basin; Detrital-zircon geochronology; Central Asian Orogenic System; Central Asian Orogenic Belt Abstract: Understanding the development of the Central Asian Orogenic System (CAOS), which is the largest Phanerozoic accretionary orogen in the world, is critical to the determination of continental growth mechanisms and geological history of central Asia. A key to unraveling its geological history is to ascertain the origin and tectonic setting of the large flysch complexes that dominate the CAOS. These complexes have been variably interpreted as deep-marine deposits that were accreted onto a long-evolving arc against large continents to form a mega-accretionary complex or sediments trapped in back-arc to fore-arc basins within oceanic island-arc systems far from continents. To differentiate the above models we conducted U-Pb geochronological analyses of detrital-zircon grains from turbidites in the composite Hangay-Hentey basin of central Mongolia. This basin was divided by a Cenozoic fault system into the western and eastern sub-basins: the Hangay Basin in the west and Hentey basin in the east. This study focuses on the Hentey basin and indicates two groups of samples within this basin: (1) a southern group that were deposited after the earliest Carboniferous ([approximately equal to]339 Ma to 354 Ma) and a northern group that were deposited after the Cambrian to Neoproterozoic ([approximately equal to]504 Ma to 605 Ma). The samples from the northern part of the basin consistently contain Paleoproterozoic and Archean zircon grains that may have been derived from the Tuva-Mongol massif and/or the Siberian craton. In contrast, samples from the southern part of the basin contain only a minor component of early Paleozoic to Neoproterozoic zircon grains, which were derived from the crystalline basement bounding the Hangay-Hentey basin. Integrating all the age results from this study, we suggest that the Hangay-Hentey basin was developed between an island-arc system with a Neoproterozoic basement in the south and an Andean continental-margin arc in the north. The initiation of the southern arc occurred at or after the early Carboniferous, allowing accumulation of a flysch complex in a long-evolving accretionary complex. Author Affiliation: (a) Department of Geological Sciences, California State University at Long Beach, Long Beach, CA 90840-3902, United States (b) Department of Earth and Space Sciences, University of California, Los Angeles, CA 90095-1567, United States (c) Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095-1567, United States (d) Structural Geology Group, China University of Geosciences, Beijing, People's Republic of China (e) Department of Geology, Mongolian University of Science and Technology, Ulaan Baatar 210646, Mongolia (f) Department of Geosciences, University of Arizona, Tucson, Arizona 85721, United States Article History: Received 15 October 2007; Accepted 6 November 2007