| Distribution of large-scale detachment faults on mid-ocean ridges in relation to spreading rates |
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| 作者姓名： | YU Zhiteng LI Jiabiao LIANG Yuyang HAN Xiqiu ZHANG Jie ZHU Lei |
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| 作者单位： | Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China;The Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China;Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China;The Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China;Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China;The Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China;Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China;The Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China;Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China;The Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China;China Ocean Mineral Resources Research and Development Association, Beijing 100860, China |
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| 基金项目： | The National Basic Research Program of China (973 Program) under contract No. 2012CB417305; COMRA Major Project under contract No. DY125-11-R-01-05; the National Natural Science Foundation of China under contract Nos 49906004 and 41104073. |
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| 摘 要： | Large-scale detachment faults on mid-ocean ridges （MORs） provide a window into the deeper earth. They have megamullion on their corrugated surfaces, with exposed lower crustal and upper mantle rocks, rela- tively high residual Bouguer gravity anomaly and P-wave velocity, and are commonly associated with ocean- ic core complex. According to 30 detachment faults identified on MORs, we found that their distances to the axis mostly range from 5 to 50 km, half-spreading rates range from 6.8 to 17 mm/a, and activity time ranges from recent to 3 Ma. Most of the detachment faults are developed on the slow spreading Mid-Atlantic Ridge （MAR） and ultra-slow spreading Southwest Indian Ridge （SWIRl, with the dominant half-spreading rates of 7-13 mm/a, especially 10-13 mm/a. Furthermore, they mostly occur at the inside corner of one segment end and result in an asymmetric seafloor spreading. The detachment faults on MORs are mainly controlled by the tectonism and influenced by the magmatism. Long-lived detachment faults tend to be formed where the ridge magma supply is at a moderate level, although the tectonism is a first-order controlling factor. At the slow spreading ridges, detachment faults tend to occur where local magma supply is relatively low, whilst at the ultra-slow spreading ridges, they normally occur where local magma supply is relatively high. These faults are accompanied by hydrothermal activities, with their relationships being useful in the study of hydrothermal polymetallic sulfides and their origin.
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| 关 键 词： | 大西洋中脊 拆离断层 岩浆活动 传播 布格重力异常 多金属硫化物 扩张速率 构造作用 |
| 收稿时间： | 2013/5/12 0:00:00 |
| 修稿时间： | 2013/8/20 0:00:00 |
Distribution of large-scale detachment faults on mid-ocean ridges in relation to spreading rates |
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| YU Zhiteng,LI Jiabiao,LIANG Yuyang,HAN Xiqiu,ZHANG Jie,ZHU Lei.Distribution of large-scale detachment faults on mid-ocean ridges in relation to spreading rates[J].Acta Oceanologica Sinica,2013,32(12):109-117. |
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| Authors: | YU Zhiteng LI Jiabiao LIANG Yuyang HAN Xiqiu ZHANG Jie and ZHU Lei |
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| Institution: | Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China;The Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China;Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China;The Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China;Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China;The Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China;Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China;The Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China;Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China;The Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China;China Ocean Mineral Resources Research and Development Association, Beijing 100860, China |
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| Abstract: | Large-scale detachment faults on mid-ocean ridges (MORs) provide a window into the deeper earth. They have megamullion on their corrugated surfaces, with exposed lower crustal and upper mantle rocks, relatively high residual Bouguer gravity anomaly and P-wave velocity, and are commonly associated with oceanic core complex. According to 30 detachment faults identified on MORs, we found that their distances to the axis mostly range from 5 to 50 km, half-spreading rates range from 6.8 to 17 mm/a, and activity time ranges from recent to 3 Ma. Most of the detachment faults are developed on the slow spreading Mid-Atlantic Ridge (MAR) and ultra-slow spreading Southwest Indian Ridge (SWIR), with the dominant half-spreading rates of 7-13 mm/a, especially 10-13 mm/a. Furthermore, they mostly occur at the inside corner of one segment end and result in an asymmetric seafloor spreading. The detachment faults on MORs are mainly controlled by the tectonism and influenced by the magmatism. Long-lived detachment faults tend to be formed where the ridge magma supply is at a moderate level, although the tectonism is a first-order controlling factor. At the slow spreading ridges, detachment faults tend to occur where local magma supply is relatively low, whilst at the ultra-slow spreading ridges, they normally occur where local magma supply is relatively high. These faults are accompanied by hydrothermal activities, with their relationships being useful in the study of hydrothermal polymetallic sulfides and their origin. |
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| Keywords: | detachment faults oceanic core complex spreading rates distribution tectonism magma supply hydrothermal vents |
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