Lancang old plants buried porphyry petrology, geochronology and genesis

Title: Lancang old plants buried porphyry petrology, geochronology and genesisAuthor: Chen HuiDegree-granting unit: Kunming University of ScienceKeywords: concealed porphyry;; zircon U-Pb age;; Re-Os isotope;; zircon group type;; geochemistry;; Lancang old factoryAbstract: Lancang old factories in the area in the late 1980s have been exposed to the drilling of small veins and porphyry skarn zone, but until 2008, the project for exposing buried rock little access to limited core of granite porphyry rocks, geochemistry, geochronology and mineralization study of the relationship with the slow progress, relevant results rare. Crisis in Strong magnets 2007 the special prospecting mining resources to succeed - Lancang County, Yunnan Lancang Lead Mine exploration project implementation to succeed, ZK153101 drilling again exposed to the three sections of granite-porphyry dyke, ZK14824 and other holes in skarn exposed to belt and molybdenum ore body in 2009, again in ZK14827, ZK14830, ZK15501 hole exposed to the multi-porphyry dyke, the final hole to expose to the main rock. Old factories, mines and hidden areas to identify characteristics of granite porphyry, granite porphyry of this rock from the geology, petrology, geochemistry, geochronology and zircon standards-based features and other aspects, the type of comprehensive study of its causes and the formation of tectonic environment.
The area exposed to the buried porphyry rocks and their related molybdenite mineralization, skarn fracture of mainly east of the F3, F4 fault line west of the 144 line -9 between the total along the F1 fault distribution, there's elevation roughly 900-1530m, there is west to east trend.
Petrological studies show that the area was light gray granite porphyry, gray, porphyritic texture and massive structure, mainly by the phenocrysts are feldspar, quartz, plagioclase and biotite, fine-grained matrix from the other axis micro-orthoclase , quartz. Geochemical studies have shown that older plants are buried granite porphyry K calc-alkaline granite, aluminum side; trace elements K, La, Hf, Tb relative enrichment, Nb, Ta, P, Ti relative loss, reflecting the orogenic granite and features of the continental crust; REE smaller average 126.56x10-6, (La / Yb) N = 12.01-24.85, moderate LREE enrichment; 87Sr/86Sr of 0.70835-0.71544, average 0.71.
SHRIMP U-Pb zircon dating confirmed that the old plant insidious Lancang porphyry emplacement crystallization age of 44.6 ± 1.1Ma, and western Yunnan Himalayan collision intracontinental orogenic main phase (65-41 Ma) at the end quite. The old factories, mines and Lancang area molybdenite Re-Os isotopic dating results (43.78 ± 0.78Ma) and granitic porphyry SHRIMP U-Pb zircon age (44.6 ± 1.1Ma) is very similar, both for the early Himalayan ( Late Eocene) of the product, and a little new age of data on rock age, and the overall porphyry hydrothermal ore-forming stage later than the basic law of diagenetic consistent.
Old plants in the zircon granite porphyry-type simple group, there are four main types and 20 subtypes. Zircon crystal mainly by {100}, {110} and {101} cylinder, cone form {211}, {110} one cylinder to the most developed, cone {] 01} and {211} are more developed, However, {101} {211} more than the development, with a low-temperature characteristics of zircon too alkaline environment. Zircon standard-type indicating shell mining porphyry is the http://www.chinamagnets.biz/ main source of the causes of the crust-mantle source mixed porphyry.
Integrated granite porphyry geochemical, zircon and isotopic characteristics to determine the standard type, the old plants should be buried porphyry is the main crustal melting, mantle-derived material in some mixture of the causes of granite porphyry. Formed in the plateau region the Cenozoic porphyry collision orogenesis into collision during evening among the main collision in space produced in the Lancang River fault zone west of the Rift Valley in the late Paleozoic, the regional dynamic environment is a collisional environment.Degree Year: 2010