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北祁连造山带东段白银地区的构造单元划分及韧性变形 被引量:15
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作者 张建新 许志琴 李海兵 《高校地质学报》 CAS CSCD 1996年第2期146-154,共9页
北祁连造山带东段的白银地区可划分出四个构造单元(B1,B2,B3和B4):B1属于中祁连变质地块,B2为古祁连洋在俯冲过程中形成的增生杂岩,B3属于加里东期的古火山岛弧,B4为孤后残余海盆。本区存在两期韧性变形:第一... 北祁连造山带东段的白银地区可划分出四个构造单元(B1,B2,B3和B4):B1属于中祁连变质地块,B2为古祁连洋在俯冲过程中形成的增生杂岩,B3属于加里东期的古火山岛弧,B4为孤后残余海盆。本区存在两期韧性变形:第一期韧性变形以形成近垂直于造山带的NE-SW向拉伸线理为特征,剪切标志显示其主要为一系列从N→S的逆冲叠覆构造,与古祁连洋向北的俯冲作用有关;第二期韧性变形形成四条韧性平移剪切带(SZ1,SZ2,SZ3和SZ4),具有近水平NWW-SEE向拉伸线理和近直立的叶理、微构造、石英组构及同构造变质作用反映其变形温度条件为500℃~350℃(从SZ1→SZ4逐渐降低)。剪切带内的剪切标志显示其为与造山带走向平行的右行平移特征,代表加里东期俯冲及碰撞作用后造山带的陆内挤出作用。 展开更多
关键词 构造单元 古火山岛弧 逆冲叠覆 造山带 韧性变形
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Contrast of Seismic Reflection Characteristics of Gas Hydrate Distribution between Northeast SCS Slope and Hengchun Ridge 被引量:1
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作者 尚继宏 李家彪 章家保 《Marine Science Bulletin》 CAS 2008年第1期64-74,共11页
By analyzing and interpreting the newly acquired seismic profile supported by the national 973 Program and synthesizing the data with other geologic & geographic information, we draw conclusions as follows, a) Two s... By analyzing and interpreting the newly acquired seismic profile supported by the national 973 Program and synthesizing the data with other geologic & geographic information, we draw conclusions as follows, a) Two seismic reflections located at the northeast South China Sea (SCS) slope and the Hengchun ridge are the Bottom Simulated Reflections (BSRs). Yet, the genesis and process of the gas hydrate in these two areas are different because of different regional tectonics and geological environments; b) The genesis of gas hydrate located at the northeast SCS slope area is related to the broadly existing fracture zones, slumping tectosomes, and the distinctive shielding environment of pressure masking field formed by them. But the genesis of the gas hydrate at the Hengchun ridge is associated with the thrust nappe structures and accretionary wedges formed along the Manila subduction zone and the related sub-floor fluid channel system built by them; c) Since the analogous geologic bodies are broadly distributed at slope areas around SCS and the temperature-press environment is very suitable to the formation and conservation of the gas hydrate, we suggest that much more of this resource should be stored in these areas. 展开更多
关键词 BSR gas hydrate slumping block accretionary wedge thrust nappe tectosome DIAPIR
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