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地处古特提斯域的牡音河组是一套由放射虫硅质岩和凝灰岩组合而成、沉积速率极低的远洋沉积序列。它所包括的４个放射虫组合指示其形成时代为晚二叠世末至中三叠世，从而大大改变了我们以往对古特提斯演化所拟定的时间表。详细的岩相和岩石地球化学分析表明，牡音河组的中、下部与大洋岛弧的火山活动关系密切，上部则有接受更多陆源物质的趋向。这一沉积记录所反映的演化趋可能标志着古特提斯残留海的一次重大构造转折。但是，牡音河组内所有火山碎屑和陆源碎屑仅仅构成若干夹在正常远洋序列中的远源薄层，这意味着古特提斯残留海仍然具有相当规模，距离完全闭合尚远。就牡音河组与相邻一些地层单位的关系，探讨了若干造山带地层学研究中值得注意的基本问题
The Muyinhe Formation, located in the Guteethis area, is a suite of oceanic sedimentary sequences formed by the combination of radiolarian cherts and tuffs with very low sedimentation rates. The four radiolarian assemblages it comprises indicate that they formed from the Late Permian to the Middle Triassic, dramatically changing our timeline for the evolution of the ancient Tethys. Detailed lithofacies and lithogeochemical analyzes show that the middle and lower parts of the Muyuhe Formation have a close relationship with the volcanic activity of the oceanic arc and the upper part has the tendency of receiving more terrigenous materials. The evolutionary trend reflected in this sedimentary record may mark a major structural turning point in the residual waters of the Guteethis. However, all pyroclastic and terrigenous debris within the Muhuanhe Formation constitute only a few remote-sourced thin layers trapped in normal oceanic sequences, suggesting that the Guteethis residual sea is still quite large and far enough away from complete closure. Based on the relationship between Muyinhe formation and some adjacent strata, some notable basic problems in stratigraphic study of several orogenic belts are discussed