中上扬子地区震旦纪末期古海洋环境研究的若干问题

本文通过调研大量文献，系统梳理了前人关于中上扬子地区震旦纪灯影期古海洋环境特征的研究方法和主要认识，特别是关于古海水的氧化还原条件、古温度和古盐度等3个要素。结果表明，震旦纪灯影组沉积时期，中上扬子地区的古海洋是一个水深较浅、并逐渐趋于氧化的浅海水体环境；古海水温度为7.0 ℃～38.6 ℃，且在灯影组晚期升高，主要为亚热带气候；海水盐度较新元古代早期有降低的趋势，但仍为海相环境，且灯影组二段和灯影组四段时期盐度相对更大。震旦纪灯影组沉积时期的古海洋环境在地质演化历史中具有重要的时空意义，能够为解释当时地球的气候条件和生物演化等方面的重大变化提供依据。现阶段研究中的问题包括：1）缺乏同时期古海洋氧化还原环境的区域对比；2）古海水绝对深度的研究十分薄弱；3）缺乏古海水盐度的直接指示依据。建议开展高分辨率古环境指示参数垂向序列和多剖面横向对比的研究，尝试定量分析氧气浓度随古海水绝对深度的变化规律，探索指示古海水盐度的直接依据。

Some important issues of the research about paleo-ocean environment of Late Sinian in middle and upper Yangtze region,South China

Based on lots of references, this paper wants to present a systematic analysis to the research methods and achievement about the environment characteristics of paleo-ocean during Dengying Formation of Sinian period at the middle and upper Yangtze region, especially on the three parameters：redox environment of the paleoseawater, paleotemperature and paleosalinity. The results indicate that it is a shallow sea with oxydic water and high paleotemperature and paleosalinity at Dengying Formation, which could give us some evidences to explain some significant change on the climate conditions and biological evolution. There are three unsolved issues of present research as follows, no correlation of the oxidation-deoxidation environment parameters, no direct study absolute depth of paleoseawater and no direct indicator to the paleosalinity. So, it is suggest that we need to build vertical high resolution profiles on some paleoenvironmental parameters, correlate the profiles of different location, analysis the change of oxygen concentration with absolute depth of paleoseawater quantitatively, and seek for the direct indicator to paleosalinity.