Integrated stratigraphy of the Kimmeridge Clay Formation (Upper Jurassic) based on exposures and boreholes in south Dorset, UK
Integrated stratigraphy of the Kimmeridge Clay Formation (Upper Jurassic) based on exposures and boreholes in south Dorset, UK
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DOI：
10.1017/s0016756801005738
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发表时间：
2001-09
影响因子：
2.3
通讯作者：
Helen S. Morgans-Bell;A. Coe;S. Hesselbo;H. Jenkyns;G. Weedon;J. Marshall;R. Tyson;Carolyn J. Williams
中科院分区：
文献类型：
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作者：
Helen S. Morgans-Bell;A. Coe;S. Hesselbo;H. Jenkyns;G. Weedon;J. Marshall;R. Tyson;Carolyn J. Williams
为了对上侏罗纪Kimmeridge粘土层进行高分辨率多学科研究，在英国多塞特郡南部的斯旺沃斯采石场钻了两个钻孔，在Metherhills钻了一个钻孔。这些岩心一起构成了靠近标准剖面的整个地层的第一个完整剖面。我们提供了记录岩心地层的图解测井，并概述了补充的地球物理和分析数据集（伽马射线、磁化率、总有机碳、碳酸盐、δ 13 Corg）。特别值得注意的是来自地层最低部分的新钻孔数据，该数据未出现在典型区域中。详细的日志可从Kimmeridge钻井项目网站http://kimmeridge.earth.ox.ac.uk/下载。更令人感兴趣的是，δ 13 Corg记录中的中性带正移，这一特征也记录在特提斯碳酸盐岩层序中，表明这是一个区域性事件，因此可能有助于相关。岩芯的岩石地层学与附近的悬崖剖面进行了精确的对比，悬崖剖面也被检查和重新描述。磁化率和光谱伽马射线测量是在一个规则的间隔通过继承，并促进核心曝光相关。露头和岩心地层细分为四种主要泥岩岩性类型：（a）中-深-深灰色泥灰岩;（B）中-深-深灰色-绿黑色页岩;（c）深灰色-橄榄色-黑色层状页岩;（d）灰-黑色-棕黑色泥岩。这些剖面还含有少量的粉砂岩、石灰岩和白云岩。通过与岩心的对比，发现同时代地层的岩性变化较小，厚度差异较大。建议将钻孔和典型剖面的不同部分与Purbeck-怀特岛扰动的接近程度作为厚度变化的可能控制因素。
For the purposes of a high-resolution multi-disciplinary study of the Upper Jurassic Kimmeridge Clay Formation, two boreholes were drilled at Swanworth Quarry and one at Metherhills, south Dorset, UK. Together, the cores represent the first complete section through the entire formation close to the type section. We present graphic logs that record the stratigraphy of the cores, and outline the complementary geophysical and analytical data sets (gamma ray, magnetic susceptibility, total organic carbon, carbonate, δ13Corg). Of particular note are the new borehole data from the lowermost part of the formation which does not crop out in the type area. Detailed logs are available for download from the Kimmeridge Drilling Project web-site at http://kimmeridge.earth.ox.ac.uk/. Of further interest is a mid-eudoxus Zone positive shift in the δ13Corg record, a feature that is also registered in Tethyan carbonate successions, suggesting that it is a regional event and may therefore be useful for correlation. The lithostratigraphy of the cores has been precisely correlated with the nearby cliff section, which has also been examined and re-described. Magnetic-susceptibility and spectral gamma-ray measurements were made at a regular spacing through the succession, and facilitate core-to-exposure correlation. The strata of the exposure and core have been subdivided into four main mudrock lithological types: (a) medium-dark–dark-grey marl; (b) medium-dark–dark grey–greenish black shale; (c) dark-grey–olive-black laminated shale; (d) greyish-black–brownish-black mudstone. The sections also contain subordinate amounts of siltstone, limestone and dolostone. Comparison of the type section with the cores reveals slight lithological variation and notable thickness differences between the coeval strata. The proximity of the boreholes and different parts of the type section to the Purbeck–Isle of Wight Disturbance is proposed as a likely control on the thickness changes.