Maastrichtian carbon isotope stratigraphy and cyclostratigraphy of the Newfoundland Margin (Site U1403, IODP Leg 342)
Maastrichtian carbon isotope stratigraphy and cyclostratigraphy of the Newfoundland Margin (Site U1403, IODP Leg 342)
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DOI：
10.5194/cp-2016-51
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发表时间：
2016-05
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通讯作者：
O. Friedrich;S. Batenburg;K. Moriya;S. Voigt;C. Cournede;Iris Möbius;P. Blum;A. Bornemann;J. Fiebig;T. Hasegawa;P. Hull;R. Norris;U. Röhl;T. Westerhold;P. Wilson;Iodp Expedition
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作者：
O. Friedrich;S. Batenburg;K. Moriya;S. Voigt;C. Cournede;Iris Möbius;P. Blum;A. Bornemann;J. Fiebig;T. Hasegawa;P. Hull;R. Norris;U. Röhl;T. Westerhold;P. Wilson;Iodp Expedition
抽象的。马斯特里赫期(白垩纪末期)的地球气候被短暂的变暖和变冷事件打断，并伴随着全球碳循环的扰动。在长期冷却趋势的叠加下，马斯特里赫斯中期以深海变暖和相对较高的稳定碳同位素比值为特征，随后是白垩纪末期强烈的气候变异性。缺乏对气候变化时间的了解，阻碍了我们对潜在原因机制的理解。我们介绍了U1403站点的综合地层学，提供了来自北大西洋的扩展深海记录(IODP探险342，纽芬兰边缘)。明显的沉积旋回性表明，轨道强迫对沉积过程起了主要作用，这一点得到了X射线荧光(XRF)扫描获得的高分辨率元素数据的统计分析的证实。天文刻度表明，所研究的层段包括7个405-KYR旋回(Ma4051-Ma4057)，横跨紧靠白垩纪/古新世(K/PG)界线之前的2.8Myr。散装碳酸盐的高分辨率碳同位素记录可以确定马斯特里赫特碳循环晚期的全球趋势。低幅度变化(高达0.4‰)是典型的公海环境，与半远洋的祖迈亚剖面(西班牙北部)进行了比较，后者具有良好的独立旋回地层格架。在这两个记录中都可以很容易地看出K/Pg前的振荡和马斯特里赫斯中期事件(MME)的负值，但在67.5 Ma左右的模式是不同的，其中U1403站更可靠地反映了全球气候变化。我们新的碳同位素记录和U1403站位已建立的旋回地层学可以作为未来详细研究北大西洋晚期马斯特里赫特事件的参考。
Abstract. Earth’s climate during the Maastrichtian (latest Cretaceous) was punctuated by brief warming and cooling episodes, accompanied by perturbations of the global carbon cycle. Superimposed on a long-term cooling trend, the middle Maastrichtian is characterized by deep-sea warming and relatively high values of stable carbon-isotope ratios, followed by strong climatic variability towards the end of the Cretaceous. A lack of knowledge on the timing of climatic change inhibits our understanding of underlying causal mechanisms. We present an integrated stratigraphy from Site U1403, providing an expanded deep ocean record from the North Atlantic (IODP Expedition 342, Newfoundland Margin). Distinct sedimentary cyclicity suggests that orbital forcing played a major role on depositional processes, which is confirmed by statistical analyses of high resolution elemental data obtained by X-ray fluorescence (XRF) scanning. Astronomical calibration reveals that the investigated interval encompasses seven 405-kyr cycles (Ma4051 to Ma4057) and spans 2.8 Myr directly preceding the Cretaceous/Paleocene (K/Pg) boundary. A high-resolution carbon-isotope record from bulk carbonates allows to identify global trends in the late Maastrichtian carbon cycle. Low-amplitude variations (up to 0.4 ‰), typical for open ocean settings, are compared to the hemipelagic Zumaia section (N-Spain), with a well-established independent cyclostratigraphic framework. Whereas the pre-K/Pg oscillations and the negative values of the Mid-Maastrichtian Event (MME) can be readily discerned in both records, patterns diverge around 67.5 Ma, with Site U1403 more reliably reflecting global climate change. Our new carbon isotope record and the established cyclostratigraphy from Site U1403 may serve as a future reference for detailed studies of late Maastrichtian events in the North Atlantic.