Physical properties, in situ structure and cyclicity of 1300 m Early Jurassic mudstones from geophysical logs in the ICDP Mochras borehole, West Wales

JET项目是一个大规模、多方面的国际研究方案，有来自13个国家的约50个项目合作伙伴，研究地球系统在其历史的关键时刻--早侏罗世--的功能，当时它受到独特的构造、岩浆和轨道压力，现代生物圈的基本方面在二叠纪末和三叠纪末大灭绝后形成。该公司计划在西威尔士莫克拉斯钻一个1.9公里深的钻孔，以恢复1.3公里长的岩心，相当于27 Ma的早侏罗世时代。JET项目的总体目标是产生独特的早侏罗世记录，从而能够以迄今为止仅对新生代尝试的尺度和分辨率来调查地球系统(即档案沉积速率=5厘米/卡或20a/毫米)，并将该独特记录与现有数据和综合模拟方法一起使用，以改变对早侏罗世地球系统动力学的理解。我们对(A)井下测井数据的解释，(B)所选岩芯的一些额外物性；(C)地震反射数据将侧重于以下目标：·沉积物的岩性特征，包括探测不整合面和岩性边界；·确定该地区的古气候和古环境历史；·描述沉积相和沉积旋回；压实，·新构造学和当代构造学知识的提高，·地震反射剖面和钻孔周围3D建模的整合和校准，·将沉积物岩心测井特性校准到井眼特征的“真实深度”，·以最具成本效益的方式最大限度地恢复地层。

The JET project is a large-scale, multi-faceted, international programme of research with about 50 project partners from 13 countries on the functioning of the Earth system at a key juncture in its history – the Early Jurassic – when it was subject to distinctive tectonic, magmatic, and orbital forcing, and fundamental aspects of the modern biosphere were becoming established in the aftermath of the end Permian and end Triassic mass extinctions. It is planned drilling a 1.9-km-deep borehole at Mochras, West Wales, to recover a 1.3-km-long core representing 27 Ma of Early Jurassic time. The overarching goal of the JET project is to generate a unique Early Jurassic record allowing investigation of the Earth system at a scale and resolution hitherto only attempted for the Cenozoic (i.e. archive sedimentation rate = 5 cm/ka or 20 a/mm), and to use that unique record together with existing data and an integrative modelling approach to produce a step-change in understanding of Early Jurassic Earth system dynamics.Our interpretation of (a) downhole logging data, (b) some additionally acquired physical properties on selected core plugs and (c) seismic reflection data will focus on the following objectives:• the characterisation of the lithology of the sediments including the detection of unconformities and lithological boundaries,• the determination of the paleoclimatic and paleoenvironmental history of this area,• the description of sediment facies and sedimentary cycles; compaction,• the improvement in knowledge about neotectonics and contemporary tectonics,• the integration and calibration of seismic reflection profiles and 3D modelling around the boreholes,• the calibration of sediment core logging properties to the ‘true depths’ of features in the borehole,• to maximize stratigraphic recovery in the most cost-effective manner.