Astronomically forced climate cooling across the Eocene–Oligocene transition in the Pearl River Mouth Basin, northern South China Sea
Astronomically forced climate cooling across the Eocene–Oligocene transition in the Pearl River Mouth Basin, northern South China Sea
复制标题
南海北部珠江口盆地始新世—渐新世过渡期间的天文强迫气候变冷
DOI：
10.1016/j.palaeo.2020.109945
复制
发表时间：
2020-11
期刊：
影响因子：
--
通讯作者：
Entao Liu
中科院分区：
文献类型：
--
作者：
Xiaosong Wei;Detian Yan;Pan Luo;Ping Jiang;Hua Wang;Jiaxiong Zhou;Fuyun Cong;Xiangrong Yang;Xing Niu;Tong Li;Lei Liu;Entao Liu
在始新世晚期-渐新世早期，全球气候和环境发生了重大变化，包括全球气温下降和南极冰川出现。这些变化标志着从早新生代温室条件向冰库条件的转变。对大西洋和高纬度地区这种冷却趋势的研究有所增加，但很少有报告研究低纬度地区(如南中国海北部)，目前尚不清楚这些地区的沉积物记录是否保留了与这一全球冷却事件有关的信号。本文研究了位于南海北部中国海北部的珠江口盆地文昌凹陷的一口湖井记录。我们进行了孢粉学和旋回地层学分析，以重建沉积环境，并评估轨道强迫的影响。旋回地层学分析表明，沉积旋回(包括向上细化和向上粗化的层序)主要受较长的偏心率控制，迫使湖系以~1.2Myr的时间间隔扩张和收缩。此外，始新世-渐新世(E-O)过渡前后孢粉组合的变化表明，文昌凹陷文昌组至恩平组记录的中深湖向三角洲相浅湖转变。这些发现表明，气候恶化是对全球变冷的回应。Ee-O转换过程中倾角强迫的放大和倾角功率与全球pCO2的共同演化表明，中国的低纬沉积记录含有高纬度信号。此外，进动、倾角和偏心旋回的低幅度与全球海平面和pCO2的初始下降以及~34.3 Ma的碳-氧同位素组成的正偏置相耦合。这些结果表明，在E-O转变过程中，轨道作用力使pCO2上升到一个临界值以上(~33.9 Ma)。
During the late Eocene–early Oligocene, major changes in the global climate and environment occurred, including decreases in global temperature and the appearance of Antarctic glaciation. These changes marked the transition from early Cenozoic greenhouse conditions to icehouse conditions. Research on this cooling trend in the Atlantic and high-latitude regions has increased, but few reports have studied low-latitude regions (e.g., the northern South China Sea), and it remains unclear whether sediment records in these areas preserve signals related to this global cooling event. In this study, we studied records from a lacustrine well in the Wenchang Sag, Pearl River Mouth Basin (PRMB), northern South China Sea. We conducted palynological and cyclostratigraphic analyses to reconstruct the depositional environment and assess the influence of orbital forcing. The cyclostratigraphic analysis showed that depositional cycles (including fining-upwards and coarsening-upwards sequences) were controlled mainly by long eccentricity, forcing the expansion and contraction of the lake system at ~1.2 Myr time intervals. In addition, changes in the pollen-spore assemblage before and after the Eocene–Oligocene (E-O) transition show a dramatic shift from a moderately deep lake to a shallow lake with delta facies, as recorded by the Wenchang to Enping Formations in the Wenchang Sag, PRMB. These findings suggest that the climate deteriorated in response to global cooling. The amplification of obliquity forcing and the coevolution between obliquity power and global pCO2during theE-O transition suggest that the low-latitude sedimentary records from China contain a high-latitude signal. Furthermore, the low amplitudes of the precession, obliquity, and eccentricity cycles are coupled with the initial decreases in the global sea-level and pCO2and a positive bias in the carbon‑oxygen isotopic compositions at ~34.3 Ma. These results suggest that orbital forcing played a role in elevating pCO2across a critical threshold during the E-O transition (~33.9 Ma).
登录
查看更多内容
DOI：
10.1016/j.palaeo.2015.10.014
发表时间：
2015-12
期刊：
Palaeogeography, Palaeoclimatology, Palaeoecology
影响因子：
--
作者：
Q. Fang;Huaichun Wu;L. Hinnov;X. Jing;Xunlian Wang;Q. Jiang
通讯作者：
Q. Fang;Huaichun Wu;L. Hinnov;X. Jing;Xunlian Wang;Q. Jiang
影响因子：
3.9
作者：
J. Zachos;L. Kump
通讯作者：
J. Zachos;L. Kump
影响因子：
56.9
作者：
BERGER, A;LOUTRE, MF;LASKAR, J
通讯作者：
LASKAR, J
影响因子：
4.3
作者：
T. Westerhold;U. Röhl;H. Pälike;R. Wilkens;P. Wilson;G. Acton
通讯作者：
T. Westerhold;U. Röhl;H. Pälike;R. Wilkens;P. Wilson;G. Acton
影响因子：
--
作者：
S. Meyers
通讯作者：
S. Meyers