Origin of the rhythmic reddish-brown and greenish-gray sediments in the abyssal South China Sea: Implications for oceanic circulation in the late Miocene
Origin of the rhythmic reddish-brown and greenish-gray sediments in the abyssal South China Sea: Implications for oceanic circulation in the late Miocene
复制标题
南海深海有节奏的红棕色和绿灰色沉积物的起源：对中新世晚期海洋环流的影响
DOI：
10.1016/j.margeo.2020.106378
复制
发表时间：
2020
期刊：
影响因子：
2.9
通讯作者：
Chuanlian Liu
中科院分区：
文献类型：
--
作者：
Xiaobo Jin;Juan Xu;Hui Li;Yanli Li;Peijun Qiao;Li Wu;Chen Ling;Baohua Li;Chuanlian Liu
在国际海洋探索计划（IODP）第368次考察期间，在南中国海北部进行了一系列钻探。在深海钻井地点1502孔A（海平面以下3764米），从海底以下442米到497米连续回收了岩心剖面。这些岩心被放置在晚中新世，这些~50 m长的岩心最显著的特征是连续出现有节奏的红棕色和绿灰色沉积物。在邻近较浅的IODP 368点1501和1505的岩心中，这种晚中新世的颜色转变并不显著。在这项研究中，我们的目的是确定深海南海1502位点上这些类似循环的颜色转变的起源。我们进行了沉积物颜色反射率、纳米化石、关键元素含量和粘土矿物的实验。我们推测，原位形成的无定形赤铁矿导致了红色沉积物的着色，其中铁和锰含量高，碳酸盐保存良好。我们认为，类似旋回的颜色转变可能是深海南海中深水通风程度的结果。深海通风的这种变化可能与太平洋深海环流的轨道强迫重排有关。
During International Ocean Discovery Program (IODP) Expedition 368, a series of drillings were conducted in the northern South China Sea (SCS). At the abyssal drilling Site 1502 Hole A (3764 m below sea level), successive core sections were recovered from 442 to 497 m below sea floor. These cores were placed into the late Miocene period, and the most remarkable feature of these ~50-m-long cores were the consecutive occurrences of the rhythmic reddish-brown and greenish-gray sediments. Such color transitions during the late Miocene period were not remarkable for the cores at the adjacent shallower IODP 368 Sites 1501 and 1505. In this study, we aimed to determine the origin of these cyclicity-like color transitions at Site 1502 in the abyssal SCS. We conducted experiments dealing with sediment color reflectance, nannofossil, key element content, and clay minerals. We inferred that the in-situ formed amorphous hematite caused the coloration of the reddish sediments, in which ferrum and manganese contents were high and carbonate was not poorly preserved. We suggest that the occurrence of the cyclicity-like color transitions could result from the extent of deep-water ventilation in the abyssal SCS. Such changes in deep-water ventilation were possibly related to an orbital-forced rearrangement of deep oceanic circulation in the Pacific Ocean.