4th International Conference of Palaeogeography

254 / 2019-06-30 18:30:47

Sediment Provenance Analysis and Tectonic Implication of the Benxi Formation, Ordos Basin

Provenance analysis; Sedimentological analysis; detrial zircon; The Benxi Formation; Ordos Basin

Erdos basin experienced lifting and dending in the Paleozoic, After that it started to subside and deposit the sea-land transition phase clastic of the Benxi Formation. For clarifying the provenance characteristic of Benxi Formation, based on the data of outcrop, core and various analytical testing tools, we analyzed the conglomerate distribution, light mineral debris component, quartz cathodoluminescence，heavy mineral suites and stability coefficient and the zircon age distribution histogram, recognized different provenance systems and then conformed the source rock types of different source system and the tectonic evolution characteristics of southern part of the basin. The result show that there are two main provenance systems which can be further divided into four provenance systems in the northern and southern basin，the northern provenance supply ability is stronger the south. The source rock of northwest provenance is Metamorphic rocks and a small amount of volcanic rocks, the northeast source rock is acidic intrusive rock, the southwest rock is high-grade metamorphic rocks, some magmatic rocks and a small amount of sedimentary rocks, the southeast source rock is high-grade metamorphic rocks. As the Benxi formation deposited, the southern provenance could reach the central part of the basin. As a main component of southern provenance system, the North Qinling terrace has been collided with the North China Block this time.