Campanian-Maastrichtian ocean circulation in the tropical Pacific
Campanian-Maastrichtian ocean circulation in the tropical Pacific
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DOI：
10.1002/palo.20051
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发表时间：
2013-09-01
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影响因子：
--
通讯作者：
Frank, Martin
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文献类型：
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作者：
Jung, Claudia;Voigt, Silke;Frank, Martin
太平洋是地球上最大的水体，太平洋的环流对最近白垩纪的气候演变做出了重大贡献，这是一段长期降温时期的顶峰。在这里，我们提供了新的高分辨率晚寒武世至马斯特里赫斯的底栖生物和浮游生物有孔虫稳定同位素数据，以及从热带太平洋(沙茨基隆起)大洋钻探计划孔1210B的沉积氧化铁锰氧化物涂层中获得的钕(ND)同位素记录。这些新记录解决了最新白垩纪1300万年的问题，提供了对表层和底层水温变化的洞察，以及涵盖坎帕尼亚-马斯特里赫特边界事件(CMBE)和中马斯特里赫特事件(MME)碳同位素漂移的深中水源区。我们新的海底有孔虫O-18和ND同位素记录以及已公布的ND同位素数据显示，在研究的范围内，在广泛的半深海到深海深度范围内，有明显的平行趋势，以反映热带太平洋深海环流强度的变化。特别是，我们观察到了马斯特里赫斯早期(72.5-69.5 Ma)长达300万年的较冷时期，伴随着向放射性成因较低的海水的转变，ND同位素特征可能标志着具有南大洋物源的深水加强混合和向北流动的时期。我们认为，这种变化是由南部高纬度深水的强化形成和对流所触发的，这一过程在MME(69.5-68.5 Ma)期间减弱。早期马斯特里赫期寒武纪与CMBE和MME碳同位素负、正变化趋势密切相关。这些长达数百万年的碳循环扰动表明，气候变冷是一种构造强迫，可能与洋盆几何结构和水深测量的变化有关。
The Pacific Ocean is the largest water body on Earth, and circulation in the Pacific contributed significantly to climate evolution in the latest Cretaceous, the culmination of a period of long-term cooling. Here, we present new high-resolution late Campanian to Maastrichtian benthic and planktic foraminiferal stable isotope data and a neodymium (Nd) isotope record obtained from sedimentary ferromanganese oxide coatings of Ocean Drilling Program Hole 1210B from the tropical Pacific Ocean (Shatsky Rise). These new records resolve 13 million years in the latest Cretaceous, providing insights into changes in surface and bottom water temperatures and source regions of deep to intermediate waters covering the carbon isotope excursions of the Campanian-Maastrichtian Boundary Event (CMBE) and the Mid-Maastrichtian event (MME). Our new benthic foraminiferal O-18 and Nd isotope records together with published Nd isotope data show markedly parallel trends across the studied interval over a broad range of bathyal to abyssal water depths interpreted to reflect changes in the intensity of deep-ocean circulation in the tropical Pacific. In particular, we observe a three-million-year-long period of cooler conditions in the early Maastrichtian (72.5 to 69.5Ma) when a concomitant change toward less radiogenic seawater Nd isotope signatures probably marks a period of enhanced admixture and northward flow of deep waters with Southern Ocean provenance. We suggest this change to have been triggered by intensified formation and convection of deep waters in the high southern latitudes, a process that weakened during the MME (69.5 to 68.5Ma). The early Maastrichtian cold interval is closely related to the negative and positive carbon isotope trends of the CMBE and MME. The millions-of-years long duration of these carbon cycle perturbations suggests a tectonic forcing of climatic cooling, possibly related to changes in ocean basin geometry and bathymetry.