Gansu Party Nan Shan Early Paleozoic tectonic nature of the study

Title: Gansu Party Nan Shan Early Paleozoic tectonic nature of the studyAuthor: Luo non-Degree-granting units: Chengdu University of TechnologyKey words: Early Paleozoic;; party Nan Shan;; volcanic rocks;; tectonic settingSummary:

Party Nan Shan in the Mongolian Autonomous County, Gansu Province, Salt Wanxiang Subei area.

Party developed a set of Mountain area in Henan early Paleozoic strata. Formation from the old to the new force were my groove group (O1-2WL), Salt Pond Bay Group (O2yc), Cardoso music group (O3ds) and Silurian Baron Gong Gaer group (Sbl). Force early in the Austrian Taoshi Wu groove group (O1-2WL) developed three lithologic, were I a power base in the basic volcanic rock groove, groove base edge, Sec I in acidic volcanic rocks, and I force Magnetic lifter ditch crystalline limestone group of three sections . One section of rock in the mafic volcanic breccia mass angular porphyry lava, lava rock spilite breccia, basaltic lava breccia, amygdaloidal basalt, massive basalt, spilite. Both tholeiitic rocks have calc-alkaline basalt series series. Acidic volcanic rock segment andesitic porphyry as, Shiying An Shan porphyry, times Shiying An Mountain porphyry. Dominated by calc-alkaline series. Constant element content and similar mafic sections. Trace element characteristics of rare earth, rare earth, low total, ΣREE39.29 ~ 1205.41μg / g, LREE / HREE = 3.42 ~ 10.51, with weak to moderate positive Eu anomalies, for the trace elements Sr, Rb, Ba, Th of selective enrichment, which is strongly enriched in Th, depleted Nb, Zr, Ti, Y, Yb, with the characteristics of island arc volcanic rocks. In the chemical composition and evolution of mafic volcanic rocks with the relationship. I force ditch Group volcanic rocks generally reflect the ocean environment and the oceanic crust on the development of ocean island volcanic arc.

Salt Pond Bay, Middle Ordovician volcanic rocks, lithology is mainly dark green to muddy siltstone, feldspathic quartz greywacke, siltstone sand quality feldspar quartz, feldspar greywacke, quartz sericite phyllite, etc. development of graded bedding. Rock composition in the mixed base and high content of calcium debris, composition and structure http://www.999magnet.com/products/131-magnetic-lifter of low maturity. A second deep - deep-sea and deep-sea mud with turbidite flysch portfolio construction, reflecting the formation of the continental slope to the abyssal plain in the transition of sedimentary environment.

Late Ordovician Cardoso music group containing sandstone and volcanic rock. Cardoso song still has a constant element volcanic rocks of oceanic tholeiite characteristics. With the South Qilian Late Ordovician volcanic rocks of the geochemical characteristics of volcanic rocks that Cardoso song is island-arc volcanic rocks, indicating the party Nan Shan exist Late Ordovician subduction.

Baron Gong Gaer Silurian rock group, the fine-grained sandstone from the lower part of the change, and change pebbly fine sandstone, siltstone sand change, change calcareous lithic sandstone, lithic sandstone, silty slate, sericite slate, chlorite slate, consisting of deep-sea flysch construction phase and the upper conglomerate, sandstone and other coarse clastic rocks of the sea - continental molasse formed. Space with north to south transition to shallow deep dustpan-like features, showing the typical characteristics of foreland basin deposits, reflecting the Silurian period of mountain areas in Henan Party ocean basin closure to continental collision stage.

The area is divided into two granite, the first phase of Cambrian - Ordovician I-type granite and adakitic rocks, the main formation period in 492 ~ 442Ma, the existence of the party responded to the Ordovician period, the South Qilian Mountain area in Henan Ocean northward subduction process. The second period of the Devonian period, IS-type granite, form the period 429 ~ 381Ma, should Qilian plate subduction. Development within the region also have 365Ma mafic dikes, on behalf of the formation of orogenic uplift, extensional stage.

According to the rocks during the formation of tectonic features of the environment, the establishment of the party Nan Shan Early Paleozoic tectonic evolution of the modes: ① early Austrian Tao Shinan Qilian ocean diving by the extensional environment to environment, in the oceanic crust formed on the basis of the intra-oceanic arc volcanic rocks, and accompanied by the Qilian belt I-type granite intrusion; ② Middle Ordovician tectonic movements had existed a quiet period, so the party to form a mountain area in Henan deep - half the deep sea turbidite flysch; ③ late Austrian Tao Shinan Qilian ocean again massive dive, and the party Nan Shan - Lajishan - fog places Hill line formed trench-arc-basin system; ④ Early Silurian at the beginning of the South Qilian ocean basin off the party Nan Shan region into the collision orogenic process, the ultimate Yu Zhi stay Fold the end of the collision orogenic century, has continued to Early - Middle Devonian, since the Late Paleozoic tectonic development of land within the new period.Degree Year: 2010