Astrochronology for the Early Cretaceous Jehol Biota in northeastern China
Astrochronology for the Early Cretaceous Jehol Biota in northeastern China
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中国东北早白垩世热河生物群的天文年代学
DOI：
10.1016/j.palaeo.2013.05.017
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发表时间：
2013-09-01
影响因子：
3
通讯作者：
Li, Haiyan
中科院分区：
文献类型：
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作者：
Wu, Huaichun;Zhang, Shihong;Li, Haiyan
中国东北早白垩世热河生物群为“有羽毛”的恐龙、原始鸟类、昆虫和早期开花植物提供了一个进化窗口。它还为早白垩世陆地生态系统的生物多样性变化提供了重要信息。本文基于高分辨率磁化率（MS）和非滞后剩磁（ARM）测量，对辽西四河屯剖面11.2 m厚的含化石湖相沉积进行了时间序列分析。MS和ARM系列沉积旋回带为120 ~ 260 cm、50 ~ 67 cm和18 ~ 42 cm。利用同一剖面的放射性同位素年龄约束，将120 ~ 260 cm、50 ~ 67 cm和18 ~ 42 cm的沉积旋回分别解释为短偏心率（130和95 kyr）、倾角（36.6和46 kyr）和进动（22.1、20.9和18 kyr）的米兰科维奇旋回。经100 kyr校正的“浮动”天文时标表明，11.2 m厚剖面的持续时间约为0.67 Myr，平均沉积速率约为1.70 cm/kyr。这个1.8米厚的主要化石层包含8层“羽毛”恐龙/原始鸟类化石，其持续时间估计短至150凯尔。结果表明，早白垩世义县组古植物学、沉积学和地球化学记录显示的气候波动可能受轨道强迫控制。(C) 2013 Elsevier B.V.版权所有
The Early Cretaceous Jehol Biota in northeastern China provides an evolutionary window for 'feathered' dinosaurs, primitive birds, insects and early flowering plants. It also provides critical information for the bio-diversity changes of the Early Cretaceous terrestrial ecosystem. Here we report a time series analysis for the 11.2-m-thick, fossil-bearing lacustrine deposits at the Sihetun section in western Liaoning, northeastern China on the basis of high-resolution magnetic susceptibility (MS) and anhysteretic remanent magnetization (ARM) measurements. A hierarchy of sedimentary cycle bands of 120-260 cm, 50-67 cm and 18-42 cm was recorded in the MS and ARM series. With available radioisotope age constraints from the same section, sedimentary cycles of 120-260 cm, 50-67 cm and 18-42 cm were interpreted as Milankovitch cycles of short eccentricity (130 and 95 kyr), obliquity (36.6 and 46 kyr), and precession (22.1, 20.9 and 18 kyr), respectively. The 100 kyr-tuned 'floating' astronomical time scale indicates that the duration of the 11.2-m-thick section is similar to 0.67 Myr and the average depositional rate is similar to 1.70 cm/kyr. The duration of the 1.8-m-thick, main fossil-bearing interval that contains 8 beds of 'feathered' dinosaur/primitive bird fossils can be estimated as short as 150 kyr. The results suggest that climate fluctuations manifested in paleobotanical, sedimentological and geo-chemical records of the Yixian Formation may have been controlled by orbital forcing during Early Cretaceous. (C) 2013 Elsevier B.V. All rights reserved.