Study On Devonian Sedimetntary And Volcanic Tectonic Environment In The Longshou Mountain Area

The structure of Longshou mountain area is complicated, and the faults, magmaand volcano act frequently,alsoshows metamorphic superposition, local migmatization,disorder of sequence stratigraphy. Sedimentary rocks of Devonian outcropssporadically, especially the predecessor not conducted exhaustive research to theDevonian Longshoushan area sedimentary environment and tectonic environment ofvolcano rock, this article is studied from the sedimentology, petrology, geochemistryand other disciplines of combined with field profile observation, thin section,chemical element analysis, test method, the formation of Devonian in Longshoumountain area. The main results are as follows:1.Devonian outcrop area is incomplete in Longshou mountain area,LaojunshanFormation and Shaliushui Formation display regional unconformity, and substantiallyto plunge in southweset, be named as a set of foothills of the accumulation phase,lacustrine red clastic rocks.2.The Laojunshan Formation basic sequence, mainly founded in the upper part ofthe group, rhythmic layer from the gravel orange feldspar quartz sandstone-graygreen clay rock; The Shaliushui Formation basic sequence mainly founded in thelower art of the group, bottom-uprhythmic layer by light purple-red color thin feldsparquartz sandstone siltstone andmudstone interbed.3.Devonian volcanic rocks mainly composed of trachyandesite, basaltic esite andminor andesite, belonging to the alkali content of the high alkaline volcanic rocks La、 Cs、 Rb、 Ba, Th lithophile elements such as the more obvious enrichment, and Y、Sr and other elements than the loss in the volcanic, Gotti index is more than10,showing the pro-continental margin characteristics.4.In the terms of tectonic environment, The north and south continent hasincorporated, the Devonian volcano rocks formed in intracontinental and extensionalenvironment, producted in Piedmont depression molasse formation.As beingclassificated according to the tectonic environment construction, the tectonicenvironment of Laojun Mountain group volcano rock is determined for intraplatevolcano rock area.