Magmatism Characteristics And Research Of Tectonic Background In North-Central Of ShanXi Province

North-central of Shanxi Province located on the special position, the eastern part is the TaiHang mountains board orogenic belt, the northeast close to south of the YanShan orogenic belt,distance between the north and northern activities plate of the north China is not more than100miles,the west is the ordos basin of north China craton stable plot.Magmatics rocks are widely distributed in Luliang period,Yanshan period, Indo-Chinese epoch and Himalayan period of the research area.This article studies on the rocks’ distribution of the different ages and the petrology,the rock geochemistry, magmatism characteristics and research of tectonic background,the aim is discussing magmatism characteristics of the different ages and effect of the magmatic,and the relationship. We can get the points as follow:The first,early proterozoic luliang period magmatic rocks in the middle-north shanxi province. The magmatic rocks are mainly distributed in the district of LvLiangShan, YunZhongShan, wutai mountains and heng heng, etc, rhizome bud mountain fai jadeite-bearing monzonite and YunZhongShan granite is typical representative, their isotope age are1801ma and1794ma. By the main, trace rare earth element geochemical study, they are calc-alkalic series of rock; Rare earth element distribution curve are a steep right type, with obvious negative Eu anomaly; Rhizome bud mountain fai jadeite-bearing monzonite and YunZhongShan granite are A type granite on the ground of metaorogeny of stretch and tension. Magma all stemmed from partial melting of the crustal material.To the field observation, in the vicinity of koji mountain rock of zhoushan fault fold belt, seven small rock mass are newly found, Lord, trace rare earth element geochemical characteristics research shows that they are calc-alkalic series of granite, light and heavy rare earth element fraction obviously, all showed that obvious negative Eu anomaly.Trace elements and rare earth elements distribution curve parallel and is very similar, explain their magma derived from the same magma source area, they are the products of the same period magmatism. Single particle zircon U-Pb method dating results show that the age of1809.3Ma.Northern shanxi luliang period rhizome bud mountain and rock mass is located in the centre of the north China craton belt, forming time is matched with north China craton earth east and west two land block collisingthe time. Therefore, on the ground of two landmass collided late-orogenic extensional stretch tectonic, crust remelting happened in the shanxi north-central areas, which leads to large granitic magma intrusion, forms rhizome bud mountain etc luliang period A type granite. Luliang period granitic magma intrusion, the formation of the rock mass played an important role of the weld of the east and west landmasses in the north-central part of shanxi, at the process of the continental crust solidification.The second, mesozoic Indosinian magmatic rocks of the North-Central Shanxi mainly contains alkaline igneous complex in Tianzhen-Yangquan and alkaline monzonitic rock in Di shuiyan, isotopes between the ages of248-210Ma.Major and trace element geochemical studies have shown that,they are both the A-type granites in the stretch and context of tension.Its causes are closely linked to the hot plume. Tianzhen-Yangquan magmatism shows that the deep continental crust of North-Central Shanxi has begun to occur activation in the Indo-early (early Mesozoic).The third, in north-central area Shanxi, Yanshan period magmatic rocks mainly acidic-intermediate-acid intrusive rocks, mostly located in the Mount Wutai-Hengshan area, a total of32rocks. To Tiewadian biotite granite and Diaoquan complex rock mass as representatives, the isotopic age is153.4Ma and127.2Ma. The Tiewadian biotite granite represent granodiorite-biotite granite series of rock mass, Diaoquan compound rockmass represent Syenite gabbro-(pyroxene) Syenite diorite-Granite (diorite) porphyry-Quartz porphyry series of rock mass. Lord, trace element geochemical study shows, Tiewadian biotite granite is the S-type granites, the magma came from partial melting of the crust in north part of Shanxi; Diaoquan complex rock mass is I type granite, Diaoquan compound rockmass is the production of upper mantle derived magma and crustal partial melting of mixture magmatic activities. The analysis thinks that they formed in the tectonic setting of the Pacific Plate to the Eurasian plate strongly squeeze caused by the collision of the middle of the North ChinaSo many of north-central Shanxi Yanshan period Neutral rock and Acid rock,show that in Mesozoic Yanshanian, north-central Shanxi continental crust had a strong activation, Specifically in the large area crustal material partial melting and local partial melting of upper mantle.The fourth,himalayan basalt are widely distributed.With FanShi basalt as representation,isotope age is63million years,belongs to paleogene. Geochemical Characteristics shows that FanShi basalt is volcanic rock sodic and alkaline.It has volcanic characteritics of intraplate rift type, tectonic background shows that it is alkaline basalt of the intraplate causes.FanShi basalt formed in extension tectonic background because of the eurasian plate overthrust.In order to fracture for channel,eruption surface formed basalt of800metres. The massive basalts activities, showed that deep magmatic activity more strongly in the period,marked that continental crust had become more activation in the Paleogene (Himalayan early)and begun rifting occurred.From LvLiang period to the himalayan period, continental crustal has experienced the stage stable-activating-activating strongly-rifting. Evolution process of the continental crust and magmatic activity has close contact.