Iron Speciation of Mud Breccia from the Dushanzi Mud Volcano in the Xinjiang Uygur Autonomous Region,NW China  

作　　者：XU Wang ZHENG Guodong MA Xiangxian Danielle FORTIN David R.HILTON LIANG Shouyun CHEN Zhi HU Guoyi 

机构地区：[1]Key Laboratory of Petroleum Resources,Gansu Province/Key Laboratory of Petroleum Resources Research,Institute of Geology and Geophysics,Chinese Academy of Sciences,Lanzhou 730000,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Department of Earth and Environmental Sciences,University of Ottawa,25 Templeton St.,Ottawa,Ontario,K1N 6N5,Canada [4]Scripps Institution of Oceanography,University of California San Diego,La Jolla,CA 92093-0244,USA [5]Key Laboratory of Mechanics on Disaster and Environment in Western China(Lanzhou University),Ministry of Education,Lanzhou 730000,China [6]CEA Key Laboratory of Earthquake Prediction(Institute of Earthquake Forecasting),China Earthquake Administration,Beijing 100036,China [7]Research Institute of Petroleum Exploration and Development,PetroChina,Beijing 100083,China

出　　处：《Acta Geologica Sinica(English Edition)》2018年第6期2201-2213,共13页地质学报（英文版）

基　　金：partially supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China(2016ZX05007001-004);the National Natural Science Foundation of China(41273112;41402129;41020124002;41402298);CAS"Light of West China"Program and Chinese Academy of Sciences Visiting Professorship for Senior International Scientists(2015VEA032)

摘　　要：Organic-inorganic interactions occurring in petroleum-related mud volcanoes can help predict the chemical processes that are responsible for methane emissions to the atmosphere. Seven samples of mud breccia directly ejected from one crater were collected in the Dushanzi mud volcano, along with one argillite sample of the original reddish host rocks distal from the crater, for comparison purposes. The mineral and chemical compositions as well as iron species of all samples were determined using XRD, XRF and M?ssbauer spectroscopy, respectively. The results indicate that a series of marked reactions occurred in the mud volcano systems, more specifically in the mud breccia when compared to the original rocks. Changes mainly included:(1) some conversion of clay minerals from smectite into chlorite and illite, and the precipitation of secondary carbonate minerals such as calcite and siderite;(2) silicon depletion and significant elemental enrichment of iron, manganese, magnesium, calcium and phosphorus; and(3) transformation of iron from ferric species in hematite and smectite into ferrous species in siderite, chlorite and illite. These geochemical reactions likely induced the color changes of the original reddish Neogene argillite to the gray or black mud breccia, as a result of reduction of elements and/or alteration of minerals associated with the oxidation of hydrocarbons. Our results also suggest that greenhouse gases emitted from the mud volcanoes are lowered through a series of methane oxidation reactions and carbon fixation(i.e., through carbonate precipitation).Organic-inorganic interactions occurring in petroleum-related mud volcanoes can help predict the chemical processes that are responsible for methane emissions to the atmosphere. Seven samples of mud breccia directly ejected from one crater were collected in the Dushanzi mud volcano, along with one argillite sample of the original reddish host rocks distal from the crater, for comparison purposes. The mineral and chemical compositions as well as iron species of all samples were determined using XRD, XRF and M?ssbauer spectroscopy, respectively. The results indicate that a series of marked reactions occurred in the mud volcano systems, more specifically in the mud breccia when compared to the original rocks. Changes mainly included:(1) some conversion of clay minerals from smectite into chlorite and illite, and the precipitation of secondary carbonate minerals such as calcite and siderite;(2) silicon depletion and significant elemental enrichment of iron, manganese, magnesium, calcium and phosphorus; and(3) transformation of iron from ferric species in hematite and smectite into ferrous species in siderite, chlorite and illite. These geochemical reactions likely induced the color changes of the original reddish Neogene argillite to the gray or black mud breccia, as a result of reduction of elements and/or alteration of minerals associated with the oxidation of hydrocarbons. Our results also suggest that greenhouse gases emitted from the mud volcanoes are lowered through a series of methane oxidation reactions and carbon fixation(i.e., through carbonate precipitation).

关 键 词：mud volcano mud breccias iron species organic-inorganic interactions greenhouse gas 

分 类 号：P[天文地球]