Late Maastrichtian carbon isotope stratigraphy and cyclostratigraphy of the Newfoundland Margin (Site U1403, IODP Leg 342)
Late Maastrichtian carbon isotope stratigraphy and cyclostratigraphy of the Newfoundland Margin (Site U1403, IODP Leg 342)
复制标题
DOI：
10.1127/nos/2017/0398
复制
发表时间：
2018-03-01
影响因子：
2.2
通讯作者：
Wilson, Paul A.
中科院分区：
文献类型：
--
作者：
Batenburg, Sietske J.;Friedrich, Oliver;Wilson, Paul A.
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。我们展示了综合大洋钻探计划(IODP)站点U1403的综合地层学，提供了来自北大西洋(342次远征，纽芬兰边缘)的扩展深海记录。明显的沉积旋回性表明，轨道强迫在沉积过程中发挥了主要作用，这一点得到了X射线荧光(XRF)岩心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(Ma(405)1至Ma(405)7)，横跨白垩纪/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使我们能够确定马斯特里赫特碳循环晚期的全球趋势。U1403站点碳同位素的低幅度变化(高达0.4%)与特提斯和太平洋开阔海洋站点记录中类似的尺度变化相匹配。U1403遗址与Zumaia段(西班牙北部)的半远洋限制盆地之间的对比要复杂得多，Zumaia段拥有完善的独立旋回地层格架。虽然在Zumaia和U1403记录中都可以很容易地看到前K/Pg振荡和马斯特里赫斯中期事件(MME)的负值，但在马斯特里赫斯晚期(67.8-66.8 Ma)类似于1Myr的时期内，模式发生了分化，其中U1403站更可靠地反映了全球碳循环。我们新的碳同位素记录和旋回地层学为U1403站位提供了未来高分辨率研究马斯特里赫期晚期古气候变化的参考剖面。
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 Integrated Ocean Drilling Program (IODP) Site U1403, providing an expanded deep ocean record from the North Atlantic (Expedition 342, Newfoundland Margin). Distinct sedimentary cyclicity suggests that orbital forcing played a major role in depositional processes, which is confirmed by statistical analyses of high resolution elemental data obtained by X-ray fluorescence (XRF) core scanning. Astronomical calibration reveals that the investigated interval encompasses seven 405-kyr cycles (Ma(405)1 to Ma(405)7) and spans the 2.8 Myr directly preceding the Cretaceous/Paleocene (K/Pg) boundary. A high-resolution carbon-isotope record from bulk carbonates allows us to identify global trends in the late Maastrichtian carbon cycle. Low-amplitude variations (up to 0.4%) in carbon isotopes at Site U1403 match similar scale variability in records from Tethyan and Pacific open-ocean sites. Comparison between Site U1403 and the hemipelagic restricted basin of the Zumaia section (northern Spain), with its own well-established independent cyclostratigraphic framework, is more complex. Whereas the pre-K/Pg oscillations and the negative values of the Mid-Maastrichtian Event (MME) can be readily discerned in both the Zumaia and U1403 records, patterns diverge during a similar to 1 Myr period in the late Maastrichtian (67.8-66.8 Ma), with Site U1403 more reliably reflecting global carbon cycling. Our new carbon isotope record and cyclostratigraphy offer promise for Site U1403 to serve as a future reference section for high-resolution studies of late Maastrichtian paleoclimatic change.