Cenozoic North Atlantic deep circulation history recorded in contourite drifts, offshore Newfoundland, Canada
Cenozoic North Atlantic deep circulation history recorded in contourite drifts, offshore Newfoundland, Canada
复制标题
DOI：
10.1016/j.margeo.2016.12.014
复制
发表时间：
2017-03-01
期刊：
影响因子：
2.9
通讯作者：
Sexton, Philip F.
中科院分区：
文献类型：
--
作者：
Boyle, Patrick R.;Romans, Brian W.;Sexton, Philip F.
在北大西洋，等深流造成了区域侵蚀不整合面，并沉积了厚度超过2公里、延伸达100公里的等深流漂积物。在漂移的地层记录已被用来重建整个新生代北大西洋深水环流的变化，但是，不确定性仍然存在的时间，强度，深度分布，这些电流的区域影响的某些方面。在这里，我们使用地震反射剖面和IODP核心数据（岩性，生物地层学和磁性地层学）的综合数据集，以记录沉积历史和当前的影响，在白垩纪的J-异常脊和东南纽芬兰脊，纽芬兰近海，加拿大的沉积记录。纽芬兰海脊处于一个关键位置，位于大西洋北方和西北部已得到充分研究的地区之间，并处于现代西部深海边界流和墨西哥湾流的路径之下。晚白垩世至早始新世沉积脊上的生物成因的远洋沉积为主，但在类似47马，早-中始新世边界附近，发育良好的等深岩漂积物开始在古水深约4000-4500米，伴随着一个数量级的增加，陆源沉积物质量积累率。从那时起，漂流沉积，被短暂的侵蚀中断，继续有增无减。这一持续性深海流出现的时间与北大西洋西部生物硅质沉积物向非生物硅质沉积物转变所推断的大西洋环流重组相一致（层位A（C））和在北大西洋北方受水流侵蚀的始新统内不整合面（IEU），在中始新统至上渐新统漂移序列内发生了沉积样式的变化，这可能与更深、更强烈的洋流有关，这些洋流侵蚀了沿着北美东部边缘的广泛层位A（U）。从晚渐新世（类似于25马）厚漂移表现出地震层压泥波沉积在一个独特的带在类似于3500-4500米paleodepth东南纽芬兰海岭。这一发展与广泛的晚渐新世通过中新世-上新世漂移积累整个北大西洋。漂流沉积的最新阶段，自上新世晚期（类似于3马），发生后转移到“现代”的循环系统更深，更大的电流，它包括混合的远洋-半远洋沉积物和冰筏碎片，反映冰川间冰期的影响沉积。(C)2017爱思唯尔B. V.保留所有权利。
In the North Atlantic Ocean, contour-following deep currents have created regional erosional unconformities and deposited contourite drifts that exceed 2 km in thickness and extend for 100 s of km. The stratigraphic records in the drifts have been used to reconstruct variations in North Atlantic deep-water circulation throughout the Cenozoic; however, uncertainties remain about certain aspects of the timing, intensity, depth distribution, and regional impact of these currents. Here, we use an integrated dataset of seismic-reflection profiles and IODP core data (lithology, biostratigraphy, and magnetostratigraphy) to document sedimentation history and the development of current effects in the Cretaceous to present sedimentary record on the J-Anomaly Ridge and Southeast Newfoundland Ridge, offshore Newfoundland, Canada. The Newfoundland ridges are in a key location, lying between well-studied areas in the northern and western North Atlantic and under the path of both the modern Deep Western Boundary Current and the Gulf Stream. Late Cretaceous through Early Eocene sedimentation on the ridges was dominated by biogenic pelagic sedimentation, but at similar to 47 Ma, near the Early-Middle Eocene boundary, well developed contourite drifts began to accrete in paleo-water depths of similar to 4000-4500 m, accompanied by an order-of-magnitude increase in terrigenous sediment mass accumulation rates. From this time forward, drift deposition, interrupted by brief episodes of erosion, continued unabated. This timing for the onset of persistent deep currents is coincident with reorganization of Atlantic circulation inferred from a change from biosiliceous to non-biosiliceous sedimentation in the western North Atlantic (Horizon A(C)) and with the current-eroded Intra-Eocene Unconformity (IEU) in the northern North Atlantic A change in sedimentation style occurred within the Middle Eocene to upper Oligocene drift sequence, and it likely was related to a shift to deeper, more intense currents that eroded the widespread Horizon A(U) along the margin of eastern North America about Early Oligocene time. Beginning in the Late Oligocene (similar to 25 Ma) a thick drift exhibiting seismically laminated mudwaves was deposited in a distinct belt at similar to 3500-4500 m paleodepth on the Southeast Newfoundland Ridge. This development correlates with widespread Late Oligocene through Miocene-Pliocene drift accumulation throughout the North Atlantic. The most recent phase of drift deposition, since Late Pliocene time (similar to 3 Ma), occurred after a shift to the 'modern' circulation system of deeper, swifter currents, and it includes mixed pelagic-hemipelagic sediments and ice-rafted debris that reflect glacial-interglacial influences on sedimentation. (C) 2017 Elsevier B.V. All rights reserved.