A 750-kyr detrital-layer stratigraphy for the North Atlantic (IODP Sites U1302-U1303, Orphan Knoll, Labrador Sea)
A 750-kyr detrital-layer stratigraphy for the North Atlantic (IODP Sites U1302-U1303, Orphan Knoll, Labrador Sea)
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DOI：
10.1016/j.epsl.2011.11.029
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发表时间：
2012-02-01
影响因子：
5.3
通讯作者：
Roehl, U.
中科院分区：
文献类型：
--
作者：
Channell, J. E. T.;Hodell, D. A.;Roehl, U.
综合大洋钻探计划(IODP)地点U1302-U1303，在拉布拉多海(Orphan Knoll)的东南侧翼钻探，保存了碎屑层和其他水文变化的代表记录，这些记录延伸了布鲁尼斯海大部分地区的冰盖/海洋相互作用的记录。年龄模型由相对古强度(RPI)和氧同位素数据(O-18)串联匹配而成。参考记录，显示布伦斯的平均沉积速率为14厘米/KYR。沉积回到海洋同位素阶段18的特点是碎屑层高于背景伽马射线衰减(GRA)密度，碎屑碳酸盐(Ca/Sr)和碎屑硅酸盐(Si/Sr)的X射线荧光(XRF)指示器中的峰值，以及冰排碎屑(IRD)代用品(重量%106微米)。年龄模型使U1302/03站点与位于大西洋IRD带中部中心的IODP站点U1308的对比成为可能，在那里已经获得了年龄模型和一组类似的碎屑层替代物。海因里希(H)层H1、H2、H4、H5和H6的年龄在两个地点类似于2KYR范围内(在U1308地点没有观察到H0、H3和H5a)，并与之前在孤儿克诺尔的工作在类似3KYR范围内一致。在U1308站，布伦斯碎屑层仅限于冰峰和冰川终止，回到海洋同位素阶段(MIS16)，并在U1302/03站有近同步的类似物。U1302/03地点的碎屑层在冰期和大多数间冰期都分布在整个记录中。我们将与IRD有关的类Heinrich层与具有多个碎屑层替代物(包括Ca/Sr)但通常与IRD无关的碎屑层区分开来，这可能归因于来自附近西北大西洋中洋海峡(NAMOC)的排水和泥石流事件的放样沉积物。U1302/03和U1308站的显著碎屑层可与中国近400Kyr来记录的洞穴(季风)记录的千年尺度特征相关联，暗示季风降水与美国Laurentide冰盖不稳定之间存在联系。U1302/03站位的碎屑层地层学提供了LIS动力学的长期记录，可以与其他陆地和海洋记录进行比较。(C)2011爱思唯尔B.V.保留所有权利。
Integrated Ocean Drilling Program (IODP) Sites U1302-U1303, drilled on the SE flank of Orphan Knoll (Labrador Sea), preserve a record of detrital layers and other proxies of hydrographic change that extend the record of ice-sheet/ocean interactions through most of the Brunhes Chron. The age model is built by tandem matching of relative paleointensity (RPI) and oxygen isotope data (delta O-18) from Neogloboquadrina pachyderma (sin.) to reference records, indicating a mean Brunhes sedimentation rate of 14 cm/kyr. Sedimentation back to marine isotope stage (MIS) 18 is characterized by detrital layers that are detected by higher than background gamma-ray attenuation (GRA) density, peaks in X-ray fluorescence (XRF) indicators for detrital carbonate (Ca/Sr) and detrital silicate (Si/Sr), and an ice-rafted debris (IRD) proxy (wt.% > 106 mu m). The age model enables correlation of Site U1302/03 to IODP Site U1308 in the heart of the central Atlantic IRD belt where an age model and a similar set of detrital-layer proxies have already been derived. Ages of Heinrich (H) layers H1, H2, H4, H5 and H6 are within similar to 2 kyr at the two sites (H0, H3 and H5a are not observed at Site U1308), and agree with previous work at Orphan Knoll within similar to 3 kyr. At Site U1308, Brunhes detrital layers are restricted to peak glacials and glacial terminations back to marine isotope stage (MIS) 16 and have near-synchronous analogs at Site U1302/03. Detrital layers at Site U1302/03 are distributed throughout the record in both glacial and most interglacial stages. We distinguish Heinrich-like layers associated with IRD from detrital layers marked by multiple detrital-layer proxies (including Ca/Sr) but usually not associated with IRD, that may be attributed to lofted sediment derived from drainage and debris-flow events funneled down the nearby Northwest Atlantic Mid-Ocean Channel (NAMOC). The prominent detrital layers at Sites U1302/03 and U1308 can be correlated to millennial scale features in the Chinese speleothem (monsoon) record over the last 400 kyr, implying a link between monsoon precipitation and Laurentide Ice Sheet (US) instability. The detrital-layer stratigraphy at Site U1302/03 provides a long record of LIS dynamics against which other terrestrial and marine records can be compared. (C) 2011 Elsevier B.V. All rights reserved.