Clay mineral changes across the Eocene–Oligocene transition in the sedimentary sequence at Xining occurred prior to global cooling
Clay mineral changes across the Eocene–Oligocene transition in the sedimentary sequence at Xining occurred prior to global cooling
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西宁沉积序列中始新世—渐新世过渡期间的粘土矿物变化发生在全球变冷之前
DOI：
10.1016/j.palaeo.2014.06.031
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发表时间：
2014-10
期刊：
影响因子：
--
通讯作者：
张春霞
中科院分区：
文献类型：
--
作者：
张春霞
青藏高原东北缘西宁盆地新生代形成了以膏层与红泥岩层交替发育为特征的优质长期沉积层序。塔山剖面的磁性地层学测年结果为16 ~ 35.7Ma。在这项研究中，散装和粘土矿物组合和磁性参数的33.1-35.7 Ma的部分进行了分析，利用X射线衍射和磁性方法，以确定始新世-渐新世气候转变的行为。沉积物中的石英、方解石、长石和粘土组分主要来源于周围集水区，石膏和白云石是自生矿物。伊利石、伊利石、不规则混层伊蒙石和蒙皂石是石膏/含石膏层和红色泥岩层中4种主要的粘土粒级（< 2 μm），表明西宁盆地集水区在35.7- 33.1Ma期间没有发生过明显的构造活动。沉积物中赤铁矿、伊利石和石膏的含量较高，表明西宁盆地的气候以干热为主。石膏、白云石和蒙皂石含量的变化主要受气候变化的控制。粘土矿物组合特征表明，在35.7- 34.1Ma期间，亚洲内陆地区经历了暖湿和干热的波动。这在~ 34.1 Ma时变为寒冷和干燥的条件，并在~ 34.1 Ma至33.1 Ma期间保持不变。与大洋记录和北方大陆记录的对比表明，大陆记录中的气候变冷发生在Oi-1（33.545 Ma）海洋沉积物中有孔虫δ 18 O主要下降之前。这表明，南极冰增长的幅度在EOT期间是不是亚洲内部干旱化的主要贡献者，可能是由于北移的副热带高压，存在于中国西北地区，并引起了在始新世晚期到渐新世早期温带移动。
During the Cenozoic, high-quality long-term sedimentary sequences formed in Xining basin at the northeastern margin of the Tibetan Plateau, which are characterized by alternating gypsiferous layers and reddish mudstone beds. The Tashan section was previously dated in detail by magnetostratigraphy, which yielded an age span of 16 to 35.7 Ma. In this study, bulk and clay mineral assemblages and magnetic parameters of the 33.1–35.7 Ma portion were analyzed using X-ray diffraction and magnetic methods to determine the behavior of the Eocene–Oligocene climate transition. Quartz, calcite, feldspar and clay fractions in sediments that are mainly derived from the surrounding catchments, gypsum and dolomite are authigenic minerals. Illite, chlorite, irregular mixed-layer illite-smectite and smectite are the four main clay-sized fractions (< 2 μm) in the gypsum/gypsiferous layers and the reddish mudstone beds, which suggest that no significant tectonic activity occurred in the catchment area of the Xining basin during the period of 35.7–33.1 Ma. Dominant hematite, illite and gypsum in the sediments indicate that the climate was dominantly hot and dry in the Xining basin. This was controlled by a “planetary” subtropical aridity zonal pattern; the variations in gypsum, dolomite and smectite content are mainly controlled by the climate changes. The characteristics of the clay mineral assemblages suggest that warm and humid fluctuations with hot and dry conditions prevailed during ~ 35.7–34.1 Ma in inner Asia. This changed to cold and dry conditions at ~ 34.1 Ma and remained so from ~ 34.1 to 33.1 Ma. Comparisons with open ocean marine records and Northern Hemisphere continental records indicate that the climate cooling in continental records occurred prior to the main drop of δ18O in foraminifera preserved in marine sediments at Oi-1 (33.545 Ma). This demonstrates that the magnitude of Antarctic ice growth during the EOT was not the major contributor to inner Asian aridification, possibly due to the northward moving of subtropical highs that existed in northwest China and was induced by temperate zones moving during the late Eocene to early Oligocene.
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DOI：
10.18307/2013.0414
发表时间：
2013
期刊：
Journal of Lake Sciences
影响因子：
--
作者：
Li Zhuolun;Chen Qing;Wang Nai-ang;Li Yu;Lu Hanghang
通讯作者：
Li Zhuolun;Chen Qing;Wang Nai-ang;Li Yu;Lu Hanghang
影响因子：
64.8
作者：
Ivany, LC;Patterson, WP;Lohmann, KC
通讯作者：
Lohmann, KC
DOI：
10.1029/2004eo200009
发表时间：
2004-05
期刊：
Eos, Transactions American Geophysical Union
影响因子：
--
作者：
J. Geissman
通讯作者：
J. Geissman
DOI：
10.1073/pnas.1210930110
发表时间：
2013-05-07
影响因子：
11.1
作者：
Hren, Michael T.;Sheldon, Nathan D.;Lohmann, Kyger C.
通讯作者：
Lohmann, Kyger C.
DOI：
10.1016/j.palaeo.2004.06.017
发表时间：
2004-11
期刊：
Palaeogeography, Palaeoclimatology, Palaeoecology
影响因子：
--
作者：
T. Hansen;P. Kelley;D. Haasl
通讯作者：
T. Hansen;P. Kelley;D. Haasl