Stratigraphy of the Cretaceous/Paleogene (K/Pg) boundary at the Global Stratotype Section and Point (GSSP) in El Kef, Tunisia: New insights from the El Kef Coring Project
Stratigraphy of the Cretaceous/Paleogene (K/Pg) boundary at the Global Stratotype Section and Point (GSSP) in El Kef, Tunisia: New insights from the El Kef Coring Project
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突尼斯埃尔凯夫全球层型剖面和点 (GSSP) 的白垩纪/古近纪 (K/Pg) 边界地层学：埃尔凯夫取芯项目的新见解
DOI：
10.1130/b36487.1
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Alegret, Laia
中科院分区：
文献类型：
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作者：
Jones, Heather L.;Westerhold, Thomas;Birch, Heather;Hull, Pincelli;Hédi Negra, M.;Röhl, Ursula;Sepúlveda, Julio;Vellekoop, Johan;Whiteside, Jessica H.;Alegret, Laia
白垩纪/古近纪（K/Pg）的分界线标志着地球历史上最大规模的物种灭绝之一，这一事件的地质证据在全球数百个地点得到了体现。位于突尼斯西北部El Kef附近的一个被广泛研究的剖面，其特征是经典的富铱K/Pg边界层，丰富且保存完好的微化石，以及整个达尼世早期明显的连续沉积，没有先前描述的结构复杂。这些特征使其在1991年被指定为大年纪基底（即K/Pg边界）的全球地层剖面和点（GSSP）。然而，露头剖面已风化，标志着GSSP的“金钉”难以定位。因此，El Kef取心项目旨在为El Kef GSSP附近的五个旋转钻孔中回收的岩心提供K/Pg过渡期间未风化沉积物的连续记录。在这里，我们展示了来自这些岩心的新的、高分辨率的岩性、生物地层学和地球化学数据。每个孔（彼此之间的距离都在~75 m以内）的地层序列出乎意料地不同，并且我们在浮游有孔虫生物带P1b中发现了一个以前未知的不整合。我们的结果提供了证据，证明El Kef的沉积并不像以前认为的那样连续或不受结构复杂性的影响。尽管面临这些挑战，我们提出了一个新的El Kef洞复合剖面和一个与南大西洋沃尔维斯岭轨道调整记录相关的年龄模型，这对于将El Kef的古环境和古生态记录置于全球背景下至关重要。
The Cretaceous/Paleogene (K/Pg) boundary is marked by one of the largest mass extinctions in Earth’s history, with geological evidence for this event being expressed in hundreds of locations worldwide. An extensively studied section located near El Kef, northwestern Tunisia, is characterized by the classic iridium-rich K/Pg boundary layer, abundant and well-preserved microfossils, and apparently continuous sedimentation throughout the early Danian with no previously described structural complication. These features led to its designation in 1991 as the Global Stratigraphic Section and Point (GSSP) for the base of the Danian (i.e., the K/Pg boundary). However, the outcrop section has become weathered, and the “golden spike” marking the GSSP is difficult to locate. Therefore, the El Kef Coring Project aimed to provide a continuous record of unweathered sediments across the K/Pg transition in cores recovered from five rotary-drilled holes located close to the El Kef GSSP. Here, we present new, high-resolution lithologic, biostratigraphic, and geochemical data from these cores. The recovered stratigraphic successions of each hole (all drilled within ~75 m of one another) are unexpectedly different, and we identified a formerly unknown unconformity within planktic foraminiferal biozone P1b. Our results provide evidence that sedimentation at El Kef was not as continuous or free from structural complication as previously thought. Despite these challenges, we present a new composite section from the five El Kef holes and an age model correlated to the orbitally tuned record at Walvis Ridge, South Atlantic Ocean, which is critical in placing the paleoenvironmental and paleoecological records from El Kef in a global context.