Depositional and Provenance Records of Upper Devonian to Lower Carboniferous Sandstones from Bachu Area, Northwestern Tarim Basin: Implications for Tectonic Evolution
Guo Chuntao
Gao Jian
Li Zhong
Zhang Lei
Abstract：Devonian-Carboniferous is the critical tectonic evolution period of the South Tianshan Ocean and the northern margin of Tarim Basin.Taking Upper Devonian to Lower Carboniferous outcrop of Bachu as the study area, this study further explores provenance, tectonic evolution and its geodynamic mechanism about the Tarim basin and the periphery orogen, based on depositional system, sandstone skeleton component, heavy minerals, especially detrial zircon geochronology analysis by LA-ICP-MS in situ U-Pb and Lu-Hf isotope.Sandstone skeleton component analysis shows that sandstone grains are dominated by mono crystalline quartz, and volcanic-metavolcanic fragments are rare.Its main provenance is the continental block provenance.The main proportions of heavy mineral assemblages are the stable heavy minerals, such as zircon, tourmaline, and TiO2 minerals.Heavy minerals analysis reflects the relatively distant source-sink systems and stable tectonic setting are possible.The geochronological samples show that the two samples have similar U-Pb age patterns and Hf isotopic compositions, mainly reflecting multiphase tectono-thermal events with age groups of 383-479Ma,710-932Ma,1752-1936Ma, and 2419-2597Ma respectively.Compared with the main potential source areas, the main provenance is the palaeohigh of Tarim basin.Meanwhile, the West Kunlunorogen and the Altunorogen may also have some contribution.However, there is no information about the northern orogenand island arcs.It shows the South Tianshan Ocean has not closed in this period, and there isn't subduction to the south in the northwestern margin of Tarim basin.In other words, the northwestern margin of Tarim basin is a passive continental margin during Late Devonian to Early Carboniferous.
Keywords：Bachu areaUpper Devonian to Lower Carboniferousdetrital zircongeochronologytectonic evolutiongeochemistry
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：14( 421-434 )