none 10.1190/INT-2019-0205.1 Society of Exploration Geophysicists Society of Exploration Geophysicists 186 121938077 226307 2021050623115500507 10.1190 2021-12-20T08:39:11Z 2020-12-07T13:32:45Z 7 Interpretation Interpretation 2324-8858 2324-8866 05 01 2021 9 2 Yufeng Li Southwest University of Science and Technology, School of Environment and Resource, Sichuan Mianyang 621010, China; Ministry of Natural Resources, Key Laboratory of Marine Mineral Resources, Guangzhou 510075, China; and Northwest University, Department of Geology, State Key Laboratory of Continental Dynamics, Shaanxi Xi’an 10069, China.(corresponding author). https://orcid.org/0000-0001-6683-5316 Renhai Pu Northwest University, Department of Geology, State Key Laboratory of Continental Dynamics, Shaanxi Xi’an 10069, China.. Gongcheng Zhang CNOOC Research Institute, Beijing 100028, China.. Qiang Han Sinopec, Institute of Exploration and Development of Northwest Branch, Urumq, XinJiang 830011, China.. Chao Yuan CNOOC Ltd, Research Institute of Zhanjiang Branch, Zhanjiang 524000, China.. Xueqin Zhao Southwest University of Science and Technology, School of Environment and Resource, Sichuan Mianyang 621010, China.. Although some giant gas fields found in the deepwater area of the Qiongdongnan Basin (QDNB), China, are often associated with mud diapirs and/or gas chimneys, no comprehensive 3D work has been undertaken to characterize them. We have conducted a 3D seismic investigation using the root-mean square, coherence, and instantaneous frequency attributes to provide a better understanding of the conduit systems in the QDNB. The results show that the conduit system that we investigated can be separated vertically into four zones in the following order: (1) a structurally diapiric weak zone at the base, followed by (2) an injected or reinjected sandstones zone, (3) a gas chimney zone, and (4) a mud volcanic zone at the top. The morphology of the structurally weak zone is elliptical, formed by the intersection of northwest–southeast- and nearly east–west-trending tectonic faults. We infer that this zone provides pathways for the ascent of the diapiric mud that was probably sourced by the underlying overpressured mudstones. The injected or reinjected sandstones zone is characterized by high amplitude anomalies, and it was probably fed by the lobes of underlying submarine fans. The gas chimney zone, which is characterized by low frequencies and weak amplitudes, is probably composed of a mixture of uprising mud and free gas formed from the underlying overpressured mudstones, whereas the mud volcano with a Christmas-tree pattern and is composed of a central crater, the southern flank of which is a mudflow, formed when the uprising mud migrating upward through faults got to the paleo seafloor. Finally, we have developed schematic illustrations that would aid in understanding the different stages of the formation and internal architecture of this conduit system. 02 18 2021 05 01 2021 T283 T297 10.1190/INT-2019-0205.1 1 10.1190/crossmark-policy library.seg.org true 2019-10-06 2020-09-23 2020-11-05 2021-02-18 the Key Laboratory of Marine Mineral Resources, Ministry of Land and Resources of China KLMMR-2018-B-07 the National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809 41672206 the National Basic Research Program of China 2011ZX05025-006-02 10.1190/INT-2019-0205.1 https://library.seg.org/doi/10.1190/INT-2019-0205.1 https://library.seg.org/doi/pdf/10.1190/INT-2019-0205.1 https://pubs.geoscienceworld.org/interpretation/article/9/2/t283/594845/determining-3d-seismic-characteristics-of-the 10.1007/978-3-662-44185-5_424 10.1029/92JB02280 10.1016/j.jsg.2012.09.003 10.1016/j.marpetgeo.2013.08.001 10.1016/j.marpetgeo.2011.06.004 10.1130/0016-7606(1998)110<1242:LBCFIF>2.3.CO;2 10.1016/0264-8172(94)90053-1 10.1016/j.marpetgeo.2019.07.033 10.1111/j.1365-2117.2007.00315.x 10.1144/SP439.13 10.1016/j.geomorph.2019.03.022 A review of mud volcanism Guliev I. S. 65 1992 Sand injectites: Implications for hydrocarbon exploration and production Hamberg L. 87 2007 10.1111/j.1365-2117.2005.00257.x 10.1007/s12665-016-5894-9 10.5194/se-9-1437-2018 10.1016/j.jseaes.2013.08.022 10.1016/j.margeo.2018.05.002 10.1016/0025-3227(96)00165-X 10.1029/2000RG000093 10.1007/978-94-007-6644-0_115-1 10.1007/s13131-015-0648-1 10.1111/gfl.12057 10.1111/bre.12136 10.1007/s00367-003-0152-z Roberts, D. T., 2014, A geomechanical analysis of the formation and evolution of polygonal fault systems: M.S. thesis, Cardiff University. 10.1306/94886A8D-1704-11D7-8645000102C1865D 0091-7613 Geology Shatsky N. S. 7 1929 10.1016/j.jseaes.2012.12.037 10.1306/13231312M933422 10.1306/11220505045 10.1111/j.1365-2117.2010.00480.x 10.1016/S0025-3227(99)00128-0 10.1016/j.dsr2.2015.06.016 10.1016/j.petrol.2017.08.053 10.1002/gj.3168 Acta Petrolei Sinica Yang B. 35 2014 Acta Petrolei Sinica Zhang G. C. 37 2016 10.1007/s11001-016-9266-3 10.1080/00206814.2018.1491014 10.1007/s12583-016-0708-2 0012-8228 Earth Science Zhong J. X. 44 2019 Natural Gas Geoscience Zhou J. 29 2018