Growth Faults in Carboniferous of Western Ireland
Growth Faults in Carboniferous of Western Ireland
复制标题
爱尔兰西部石炭系生长断层
DOI：
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发表时间：
1978
期刊：
影响因子：
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通讯作者：
M. Rider
中科院分区：
文献类型：
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作者：
M. Rider
在爱尔兰西部的克莱尔郡，纳穆里阶由砂岩-页岩层序组成，由反复向上变粗的三角洲旋回层组成，每个旋回层厚200至400英尺（60至120米）。这些旋回层的沉积学细节表明，它们沉积在三角洲的高负荷输入，但低波和沿岸漂移的影响，古代序列是可比的现代密西西比三角洲。同沉积扰动是旋回层的重要组成部分：控制和主导特征是生长断层。这些都是勺形的正断层，倾向于电流，并有一个陡峭的上表面，向下进入一个平坦的剪切面。勺状构造的内部几乎完全被分流口砂岩的超厚层序所充填。有人建议，生长断层县克莱尔简单地表明释放重力固有的沉积柱与倒置的密度剖面（砂轻，更移动的粘土）像前面的一个分流。断层作用释放的重力使整个三角洲块体向下和盆地内移动，就像一个巨大的“三角洲滑动”，受到连续快速沉积的助长。层序中生长断层的存在既是典型的，也是典型的增生类型的症状。
In County Clare, western Ireland, the Namurian consists of a sandstone-shale sequence made up of repeated coarsening-upward, deltaic cyclothems, each 200 to 400 ft (60 to 120 m) thick. Sedimentologic details of these cyclothems indicate that they were deposited in deltas of high load input but low wave and littoral-drift influence; the ancient sequences are comparable to those of the modern Mississippi delta. Syndepositional disturbances are an essential part of the cyclothems: the controlling and dominant feature is that of growth faults. These are scoop-shaped normal faults, that dip down current, and have a steep upper surface which passes downward into a flat shear plane. The insides of the scoops are filled almost entirely by overthickened sequences of distributary-mouth sandstones. It is suggested that the growth faults of County Clare simply indicate the release of gravity forces inherent in a sediment column with an inverted density profile (sands over lighter, more mobile clays) like that in front of a prograding distributary. Release of the gravity forces by faulting allowed the entire delta mass to move downward and basinward, as an enormous "delta slip" abetted by continuous, rapid sedimentation. The presence of growth faults in the sequence is both typical and symptomatic of the type of progradation.