Papers by Author: Jian Guo Huang

Abstract: The Middle Cambrian Tianpeng Formation volcanic rock, which was found in Baishiyan area in Wenshan recently, is the typical basalt. Through the research of Tianpeng Formation Sedimentary Enviroment and analysis of the geochemistry which includes the major elements, REE and Trace Element in the volcanic rock, SiO2 is 45.78-54.88%, total alkali (alk)=1.22-4.97 and K2O/Na2O=0.03-0.53, we can say that it should be tholeiite series. ∑REE=48.60-157.11ppm,LREE/HREE7.56-9.48,δEu0.40-1.05.REE distribution patterns show oblique to the HREE side and enrichment in LREE , the Eu anomaly is not obvious. We can see from the Trace Element Correlogram that the volcanic in this area is formed from the intiaplate basalt environment. The Tianpeng Formation in this area is clastic rock in a shallow sea and a basin facies and also is the deposit of flysch-simiflyschoid of siliceous and carbonate rock. Also, it deposit with the some undercompensation basin like laminated striation structure. All of those reflect that the structure background of the Middle Cambrian in Wenshan area has strong tensive back-arc spreading.

Abstract: The Late Triassic Tumugou Formation volcanic rocks which belongs to typical island arc volcanic rocks in southern end of Yidun island arc belt is located at the eastern of the Zhongdian ,NW Yunnan, SW China. The volcanic rocks can be divided into three categories:andesitic basalt, andesite, quartz andesite, etc. Through geochemical analysis the major elements, rare earth ele and trace element in volcanic rocks, SiO255.18-57.59×10-2,TiO21.16-1.45×10-2,Na2O+K2O5.11-8.05×10-2.consider it is calc-alkaline- alkaline Series of high-K andesite, volcanic may be controlled by the crystal fractionation of magma.Rb31.50-101×10-6,Ba1310-12300×10-6,Nb/Ta11.4-15.5,REE166.07-240.78×10-6,δEu0.74-1.00,REE distribution patterns show oblique to the HREE side and enrichment in LREE .Eu anomaly is not obvious. It is can see from the relevant figure about trace element, it is very similar in magmatic distribution patterns between volcanic rock and Volcanic-arc rock, indicating that the volcanic in this area may be formed in volcanic-arc environment. From east to west, Magma source depth have regular change with the really thickness of mainland shell. Explain that Tumugou Formation volcanic rock is subduction by Ganzi- Litang Ocean basin from east to west. Hongshan-Ousaila region of eastern edge of Zhongdian is the volcanic island arc system during the passive continental margin into an active continental margin.