冀北四岔口盆地早期热河生物群的埋藏环境分析

Analysis of the Burial Environment of the Early Jehol Biota in the Sichakou Basin, North Hebei Province

摘要: 热河生物群(约1.31~1.20亿年前)是世界级化石宝库，有关其化石大量且精美保存的埋藏机制是古生物研究的重要方向之一。但目前关于早期热河生物群的埋藏环境研究进展与这些古生物的重要性并不相称。河北省丰宁县四岔口盆地花吉营组地层埋藏有大量热河生物群化石，是早期热河生物群的重要代表地。本文对该地区一处新发现的大型恐龙化石赋存地层的沉积物进行了部分元素(包括Sr, Ba, Rb, Cr, V, Co, Hg和S)分析。元素及其比值组合特征表明该地区存在明显的火山活动，且该组地层沉积于氧化–弱还原环境多次快速更替的淡水环境。其中，S含量与V/Cr比值显著线性相关(r = 0.84; p < 0.01)，指示可能是频发的火山运动导致古水体弱还原环境的多次出现。与中–晚期热河生物群相比，早期热河生物群化石埋藏时的气候更加温暖湿润，埋藏水体也相对富氧。

Abstract: The Jehol Biota, which thrived from approximately 131 to 120 million years ago, is a world-class fossil treasure trove, and the burial mechanism of its abundant and exquisitely preserved fossils is one of the important directions in paleontological research. However, progress regarding studying the burial environment of early Jehol Biota has yet to match the significance of these fossils. Many notable fossils of the early Jehol Biota have been unearthed in the Huajiying Strata of the Sichakou Basin, Hebei Province, which is a pivotal site for understanding the early Jehol Biota. In this preliminary study, fossil-bearing sediments were first collected in Youfanggou, where a well-preserved giant dinosaur was recently discovered. Subsequently, elements including Sr, Ba, Rb, Cr, V, Co, Hg, and S were analyzed. The elemental contents and their ratios collectively indicate significant volcanic activity in this area. Additionally, these sediments were deposited in a freshwater environment characterized by rapid alteration between oxidation and weak reduction conditions. Furthermore, sediment S content is significantly linearly correlated with the corresponding V/Cr ratios (r = 0.84; p < 0.01), suggesting that frequent volcanic activities may have led to the repeated occurrence of weakly reducing environments. Compared to the mid-late Jehol Biota, the climate during the early Jehol Biota fossil burial was warmer and more humid, with relatively oxygen-rich burial water.