| 南阳盆地西峡赵营村上白垩统高沟组恐龙蛋化石埋藏特征及古环境意义 |
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| 关键词:Nanyang Basin Upper Cretaceous dinosaur egg fossil paleoenvironment |
| 基金项目:河南省财政厅“淅川盆地恐龙蛋多样性及古生态研究, 2018年度探矿权采矿权使用费和价款地质科研项目”(编号: 豫政采(2)20180300-4) |
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| The Dinosaur Egg Embedding Characteristics and Palaeoenvironmental Significance for the Upper Cretaceous Gaogou Formation in Zhaoying Village, Xixia County, Nanyang Basin |
| Lots of dinosaur egg fossils, especially famous “Baby Louie” dinosaur egg embryo fossils, exist in the Upper Cretaceous Gaogou Formation in Zhaoying Village of Nanyang Basin, Henan Province. Based on sampling and proxy analysis from the section of embedding egg fossils, the authors constructed palaeoclimate and palaeoenvironment and investigated paleoenvironmental background and reason for dinosaur extinction in the Cretaceous. A 267.8 m section was determined in the Zhaoying Village, which is made up of Upper Cretaceous Gaogou Formation overlying Devonian Nanwan Formation. Based on analysis of bulk sediment elements as well as carbon and oxygen isotopes, the authors detected that sediments in the Gaogou Formation mainly came from the magmatic rocks from the Xionger Mountain. Dinosaur egg fossils embedding in situ were kept in the flood plain belt near the foot of the mountain to the far plain with a range of 200 to 800 m. Runoff in the river and surface came from precipitation. River and flood plain environments changed quickly with the changing precipitation so that dinosaurs migrated between the foot of the mountain and the flood plain. Under the warm and wet condition, higher runoff formed the flood plain sediment environment with muddy silt rocks, which was favorable for the dinosaur living, egging and hatching. When the precipitation rose, flood plain environment was covered by the river and made dinosaur migrate back. Judging from the survived complete dinosaur egg fossil and the proxies significance, the authors hold that river hydrodynamic action was not very strong and ascended slowly. Organic matter in the strata containing dinosaur egg fossils came from germ, alga, and aquatic and terrestrial plants, but with poor vegetation as shown by the biomarker analysis. Geochemical proxies Si/Al, CIA, Rb/Sr and carbon and oxygen isotopes of carbonates show that paleoclimate of the Gaogou Formation changed quickly as a warm/dry – warm/wet – dry – warm/wet – dry process, and had a drying tendency. Under the dry condition, precipitation and effective humidity decreased, runoff decreased also with rare vegetation cover so that huge animals could not find enough food for living. Based on the research on the dinosaur egg embedding and Late Cretaceous paleoclimatical reconstruction for Zhaoying Village of Xixia County, Henan Province, it is held that the main factors causing gradual extinction of dinosaur were the palaeoclimatical and paleoenvironmental deterioration which made lots of dinosaur eggs hatch incompletely and vegetable decreased largely. |
| JIA Song-hai,XU Li,CHANG Hua-li,GAO Yong-li,ZHNAG Cheng-jun.2020.The Dinosaur Egg Embedding Characteristics and Palaeoenvironmental Significance for the Upper Cretaceous Gaogou Formation in Zhaoying Village, Xixia County, Nanyang Basin[J].Acta Geoscientica Sinica,41(3):431-442. |
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