应用自然伽马能谱法恢复碳酸盐岩沉积时的古水深——以山西兴县关家崖马五5亚段为例

    Application of natural gamma energy spectrum method for paleobathymetric recovery during carbonate deposition: A case study of M55 sub-member of Guanjiaya section in Xing County of Shanxi Province

    • 摘要: 古水深分析对还原古环境与盆地构造演化历史具有重要的意义。目前古水深恢复多以定性为主,对样品可靠性的要求较高,且易受资料条件限制,而自然伽马能谱法具有易获取、成本低、受控因素少等优点,可结合水深函数半定量恢复水深,但该方法多被用于陆相碎屑岩的研究中,是否适用于海相碳酸盐岩尚需验证。以鄂尔多斯盆地关家崖剖面奥陶系马家沟组五5亚段为例,利用自然伽玛能谱法恢复了碳酸盐岩沉积时的古水深,恢复结果与碳同位素法、生物遗迹法、岩石组构法显示的结果一致。研究验证了自然伽马能谱法在恢复碳酸盐岩沉积时的古水深方面具有较高的可信度与实用性。

       

      Abstract: The paleobathymetric analysis is of great significance to the paleoenvironment reconstruction and tectonic evolution of the basin. At present, paleobathymetric recovery is mainly qualitative, with high requires of sample reliability and is easy to be limited by the data condition. The natural gamma energy spectrum method has the advantages of accessiblity, low cost and few controlled factors, and can be used to semi-quantitative paleobathymetric recovery based on bathymetric function. However, this method is mostly used in terrestrial clastic rock deposition and its suitability for marine carbonate rock deposition is not clear. Taking the M55 sub-member of Ordovician Majiagou Formation in Guanjiaya section of Ordos Basin as an example, the authors in this paper used the natural gamma energy spectrum method to reconstruct the paleobathymetry of carbonate sediments. This method has good consistency and same results obtained by carbon isotopic method, biological heritage method and rock fabric method. The credibility and practicability of natural gamma energy spectrum method in recovering paleobathymetric recovery was also proven.

       

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