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Abstract:The static flux chamber method was applied to study natural emissions of methane to the atmosphere in the Luntai fault region of Yakela Condensed Oil/Gas Field in the Tarim Basin, Xinjiang Municipality, northwestern China. Using an online method, which couples together a gas chromatography/high‐temperature conversion/isotope ratio mass spectrometry (GC/C/MS), 13C/12C ratios of methane in flux chambers were measured and showed that methane gases are liable to migrate from deep oil/gas reservoirs to the surface through fault regions and that a part of the migrated methane, which remains unoxidized can be emitted into the atmosphere. Methane emission rates were found to be highest in the mornings, lowest in the afternoons and then increase gradually in the evenings. Methane emission rates varied dramatically in different locations in the fault region. The highest methane emission rate was 10.96 mg/m2.d, the lowest 4.38 mg/m2, and the average 7.55 mg/m2.d. The 13C/12C ratios of the methane in the flux chambers became heavier as the enclosed methane concentrations increased gradually, which reveals that methane released from the fault region might come from thermogenic methane of the deep condensed oil/gas reservoir.

Abstract:The Hehuaping tin deposit is a large deposit found in recent years during geological surveys. The discovered tin deposit includes not only rock‐alteration type deposits in fault zones, but also deposits developed in interstratifled rupture zones between Devonian carbonate rocks (Qiziqiao Formation) and sandstone (Tiaomajian Formation). The finding of tin deposits of the latter type has greatly enriched tin‐mineralization types in the famous Nanling polymetallic metallogenetic region and may provide us with a new potential orientation for prospecting of tin deposits in the region. It is commonly believed that the forming of the tin deposits in the Nanling region should be related to the Yanshanian instead of Indosinian granitic magmatism. Systematical zircon U‐Pb SHRIMP dating in this paper shows that tin mineralizations have endured at least two stages. The early stage should be related to the intrusion of the main body of the Wangxianling granite, which was emplaced during the Indosinian period with a diagenetic and mineralized age of 224.0±1.9 Ma (MSWD=0.54), and the late stage should be related to the intrusion of Yanshanian granitic porphyry that took place after 142±3 Ma (MSWD=0.5).

Abstract: The Yinshan deposit, one of the large-scale Cu-Pb-Zn-Au-Ag polymetallic deposits, may be named a middle-low temperature subvolcanic hydrothermal deposit and referred to as the“transitional deposit” linking mineralization of the epithermal and porphyry copper types. In this paper, the characteristics and structures of ore zoning are briefly described. On the basis of the dynamics of ore-forming processes and applying computer numerical simulation technique, the mechanism of ore zoning is discussed and a concealed igneous body controlling ore deposition at depth of the Yinshan mine is predicted.