Study On Cambrian-Ordovician Stratigraphy Of Xunyan-Baihe Area And Its Sedimentary Environment Analysis In Southern Qinling

Basing on the regional geological exploring and mineral surverying(scale at 1:50000), the author studies the stratum of Cambrian-Ordovician in Xunyang-Baihe area by field geology survey. The character of stratum is more systemical researched and compared by studing its field occurrence,rock association, rock chemistry, rock geochemistry, space spreading feature and sedimentary environment,etc..In near three years of field survey and general research, the author acquires some viewpoint, following as:1.The strata system of studing region is further redefined, which belongs to Niushan minor strata area of Diebu-Xunyang strata divisionand.And original Cambrian-Ordovician Donghe Group is divided into the lower Cambrian Lujiaping Formation, Cambrian Jianzhuba Formation, Ordovician Donghe Formation and the upper Ordovician-lower Silurian Banjiuguan Formation by making use of basin analysis theory,strata ording of Shan'xi province and former investigation.2. According to field survery and research, section drawing, data collect in the room and every formation rock association feature, Donghe Formation is divided into upper member, middle member, and lower member in Xunyang area.And in Baihe area, Jianzhuba Formation is divided into upper member, lower member.3.The dissertation compares rock association feature of Cambrian-Ordovician stratum between Xunyang area and Beihe area in vertical and horizontal, and simple analyses their space spread ,which has certain reference in studing palaeogeography of this region.4.Basing on the former investigation, integrating rock association,rock chemistry and geochemistry feature of every formation, the author hold that all of Cambrian-lower Silurian stratum's sedimentary environment are sea facies: Lujiaping Foramtion is inferior abyssal facies.Jianzhuba Formation is land limiting basin sedimentary.Sedimentary environment of Donghe Formation is shallow sea and low energy. Banjiuguan Formation's is deep water restoring and lingering. Water depth is deepest-deep-deeper-deepest from Lujianping Formation to Banjiuguan Formation.