Magnetostratigraphy of the Toarcian Stage (Lower Jurassic) of the Llanbedr (Mochras Farm) Borehole, Wales: basis for a global standard and implications for volcanic forcing of palaeoenvironmental change
Magnetostratigraphy of the Toarcian Stage (Lower Jurassic) of the Llanbedr (Mochras Farm) Borehole, Wales: basis for a global standard and implications for volcanic forcing of palaeoenvironmental change
复制标题
DOI：
10.1144/jgs2017-120
复制
发表时间：
2018-04
影响因子：
2.7
通讯作者：
Weimu Xu;C. Mac Niocaill;M. Ruhl;H. Jenkyns;J. Riding;S. Hesselbo
中科院分区：
文献类型：
--
作者：
Weimu Xu;C. Mac Niocaill;M. Ruhl;H. Jenkyns;J. Riding;S. Hesselbo
下侏罗世Toarcian阶段(约183-174 Ma)是全球显生界最大的外生碳循环扰动之一，与早期Toarcian大洋缺氧事件(T-OAE；约183 Ma)有关。T-OAE的气候和环境变化在海洋领域受到了相当好的限制，在T-OAE负碳同位素漂移的同时，海洋缺氧或正己烷条件在两个半球局部发展。然而，不同古海洋盆地之间以及与大陆之间的高分辨率地层学比较可能是复杂的。古地磁反转可以在海相和陆相沉积档案之间，甚至在沉积和火成岩序列之间提供精确和准确的地层对比工具。在这里，我们介绍了威尔士卡迪根湾盆地生物地层完整和扩大的Llanbedr(Mochras Farm)钻孔中Toarcian期的高分辨率磁性地层学记录。这项研究提供了第一个与高分辨率生物地层学和碳同位素地层学相结合的地磁极性反转标尺。这一地层格架还提供了与卡鲁-费拉尔大火成岩省玄武岩熔岩序列的新的、精确的对比，将普连斯巴契亚-托阿尔西亚边界和T-OAE气候和环境扰动直接与这一重大火山活动联系起来。补充材料：有关古地磁数据和倾角方向的详细信息，请访问https://doi.org/10.6084/m9.figshare.c.4052720
The Lower Jurassic Toarcian Stage (c. 183–174 Ma) is marked by one of the largest global exogenic carbon-cycle perturbations of the Phanerozoic, which is associated with the early Toarcian Oceanic Anoxic Event (T-OAE; c. 183 Ma). Climatic and environmental change at the T-OAE is reasonably well constrained in the marine realm, with marine anoxic or euxinic conditions developing locally across both hemispheres, at the same time as the T-OAE negative carbon-isotope excursion. However, high-resolution stratigraphic comparison between different palaeo-ocean basins and with the continental realm can be complicated. Palaeomagnetic reversals can provide a precise and accurate stratigraphic correlation tool between marine and continental sedimentary archives, and even between sedimentary and igneous successions. Here, we present a high-resolution magnetostratigraphic record for the Toarcian Stage in the biostratigraphically complete and expanded Llanbedr (Mochras Farm) Borehole, Cardigan Bay Basin, Wales. This study provides the first geomagnetic polarity reversal scale that is integrated with high-resolution biostratigraphy and carbon-isotope stratigraphy for the entire Toarcian Stage. This stratigraphic framework also provides a new, precise correlation with the basalt lava sequence of the Karoo–Ferrar Large Igneous Province, linking the Pliensbachian–Toarcian boundary and T-OAE climatic and environmental perturbations directly to this episode of major volcanic activity. Supplementary material: Details of the palaeomagnetic data and dip direction are available at https://doi.org/10.6084/m9.figshare.c.4052720