“路易贝贝”产出层位时代及其古环境

    The geological age and paleoenvironment of Baby Louie-bearing strata

    • 摘要: “路易贝贝”恐龙胚胎化石产于中国河南省南阳市西峡县阳城乡,位于西峡盆地上白垩统高沟组下(底)部,是Macroelon-gatoolithus xixaensis(西峡巨型长形蛋)的胚胎骨骼化石。西峡盆地上白垩统自下而上划分为高沟组、马家村组、寺沟组。高沟组产有丰富的恐龙蛋化石和少量恐龙骨骼化石,以及少量的双壳类、腹足类、介形类、轮藻、植物孢粉、植物化石碎片和丰富的遗迹化石。依据上述化石的地质时代并结合高沟组与上覆马家村组整合接触关系和寺沟组化石组合情况,以及高沟组与下伏泥盆系南湾组角度不整合接触关系和周边相邻盆地的地层对比,将西峡盆地高沟组地质时代置于晚白垩世中晚期的康尼亚克期(Coniacian)。高沟组下、中部为半干旱温热气候条件下的红色陆相类磨拉石建造的陆源碎屑岩,属间歇性的、以牵引流为主的浑水河流冲积扇沉积物;高沟组上部为冲积扇和辫状河沉积。“路易贝贝”所在层位的古地理环境是冲积扇扇端朝向南的、缓坡状宽阔平坦的冲积扇扇面,可归入冲积扇相-扇端亚相-漫流微相。

       

      Abstract: "Baby Louie" dinosaur fossil embryo, located at the bottom of Upper Cretaceous Gaogou Formation in Xixia Basin, was excavated from Zhaoying Village of Yangcheng Township in Xixia County of Nanyang City, Henan Province. Upper Cretaceous strata of Xixia Basin can be divided from bottom to top into Gaogou Formation, Majiacun Formation and Sigou Formation. "Baby Louie" is embryonic skeleton fossil of Macroelongatoolithus xixaensis. Gaogou Formation is rich in dinosaur egg fossils and little dinosaur bone fossils as well as a few fossil fragments of bivalve, gastropods, Ostracods, Charophyceae, plant pollen, and plant fossil together with abundant trace fossils. According to geological age of fossils in combination with conformable contact between Majiacun Formation and Gaogou Formation as well as fossil assemblage of Sigou Formation, angular contact between Gaogou Formation and Lower Devonian Nanwan Formation and stratigraphic correlation with surrounding basin layers, the authors hold that geological epoch of Gaogou Formation in Xixia Basin should be Late Cretaceous Coniacian. The lower and middle Gaogou Formation seems to be terrigenous clastic rocks of semi-arid red continental type molasse-like formation belonging to alluvial fan and braided river sedimentation of intermittent muddy waters, whereas the upper part of Gaogou Formation seems to be alluvial fan and traction current deposit. The horizontal paleo-geographic environment of "Baby Louie" is flat and wide alluvial fan facing south at the alluvial end, which can be classified as alluvial fan facies-fan end subfacies-flowing microfacies.

       

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