Stratigraphy of the Worston Shale Group (Dinantian), Craven Basin, north-west England
Stratigraphy of the Worston Shale Group (Dinantian), Craven Basin, north-west England
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英格兰西北部克雷文盆地沃斯顿页岩群（迪南田）地层学
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发表时间：
1990
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通讯作者：
N. Riley
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作者：
N. Riley
厄普等人（1961年）的沃斯顿页岩群由四个地层组成：克利瑟罗石灰岩、霍德泥岩、霍德伦斯石灰岩和彭德赛德石灰岩。在这些地层中定义了15个成员：桑顿石灰岩，Coplow石灰岩，Peach Quarry石灰岩，Bellman石灰岩，石灰窑木材石灰岩。菲尼斯泥岩，怀特莫尔石灰石，赫顿贝克石灰石，利格拉姆泥岩，巴克班克斯砂岩，恩布赛石灰石，雨吉尔石灰石，柴格利石灰石，Twiston砂岩和拉德布鲁克泥岩。在霍德泥岩地层中的一个特殊的床，Dunbarella床，也被认可。识别出四个不一致。分布最广的是霍德泥岩组的底部;其他的，更受限制的，出现在恩布赛石灰岩段（和等同物）的底部，Twiston砂岩段的底部和Pendleside石灰岩组的底部。诊断Visean有孔虫和牙形刺首先进入霍德泥岩组的基底部分，这表明Tournaisian-Visean边界比以前假设的要高得多。Arundian至Asbian间隔的所有Dinantian阶段边界都已重新对比。克雷文盆地被认为是由前石炭纪基底内的不对称地堑和盆地的沉积历史，从同沉积构造和海平面升降过程的组合造成的。因此，盆地沉积物描绘了从碳酸盐陆棚到斜坡的过渡（Gawthorpe 1987），涉及到克利瑟罗石灰岩和霍德泥岩地层沉积期间的变化，从盆地内生成的浅水碳酸盐岩到深水半远洋沉积物，其中石灰岩浊积岩来自周围的碳酸盐陆棚和台地。陆源砂和改造动物群间歇性地进入盆地与周围地区的出现和侵蚀有关。
SUMMARY The Worston Shale Group of Earp et al. (1961) is made up of four formations: the Clitheroe Limestone, Hodder Mudstone, Hodderense Limestone and Pendleside Limestone. Within these formations fifteen members are defined: the Thornton Limestone, Coplow Limestone, Peach Quarry Limestone, Bellman Limestone, Limekiln Wood Limestone. Phynis Mudstone, Whitemore Limestone, Hetton Beck Limestone, Leagram Mudstone, Buckbanks Sandstone, Embsay Limestone, Rain Gill Limestone, Chaigley Limestone, Twiston Sandstone and Rad Brook Mudstone. A particular bed within the Hodder Mudstone Formation, the Dunbarella Bed, is also recognised. Four unconformities are recognised. The most widespread is at the base of the Hodder Mudstone Formation; the others, which are more restricted, occur at the base of the Embsay Limestone Member (and equivalents), at the base of the Twiston Sandstone Member and at the base of the Pendleside Limestone Formation. Diagnostic Visean foraminifera and conodonts first enter within the basal part of the Hodder Mudstone Formation, suggesting that the Tournaisian-Visean boundary lies much higher than previously supposed. All the Dinantian stage boundaries in the Arundian to Asbian interval have been re-correlated. The Craven Basin is thought to have been underlain by an asymmetric graben within the pre-Carboniferous basement and the depositional history of the basin to have resulted from a combination of both syndepositional tectonics and eustatic processes. Consequently, the basinal sediments portray a transition from carbonate shelf to slope (Gawthorpe 1987), involving a change during deposition of the Clitheroe Limestone and Hodder Mudstone formations from shallow-water carbonates, generated within the basin, to deep-water hemi-pelagic sediments with limestone turbidites fed from the surrounding carbonate shelves and platforms. Intermittent supply into the basin of terrigenous sand and reworked faunas is related to the emergence and erosion of the surrounding areas.