通过综合岩相和生物群落特征对贵州罗甸干田坳晚二叠世生物礁进行分析，将研究区划分出三期造礁旋回。对造礁海绵在三个造礁阶段，以及礁前砾屑岩的成分面积进行统计，计算出各阶段的造礁成分组成状况，还原当时的造礁群落。共鉴定出纤维海绵纲3科4属，房室海绵纲9科10属和硬海绵纲2科2属。数据表明自始至终纤维海绵纲的小领针海绵属都为造礁群落里的优势生物，其中 S1阶段房室海绵纲的多囊腔海绵属种、叠瓦腔海绵属种和泡腔海绵属种为造礁主体；S2阶段小领针海绵和一纤维海绵未知属种为造礁主体，S3阶段房室海绵的多囊腔海绵占造礁主导地位。统计表明造礁海绵群团的分异度由 S1至 S3期降低明显。同时着重对本礁点主体的S2阶段骨架礁岩各个部分的结构特征进行细致分析，尤其是 RFC的形成历史进行探讨，碳氧同位素测试得到的数据表明 S2阶段古水温经历了高达16℃左右的波动，而 RFC 形成时的古水温为37．86℃，它是一种高温海水的反映；最后通过与南盘江盆地同期的紫云礁和茅口期的广西隆林礁进行对比，揭示它们的成礁模式和演化的异同。

In the late Permian there are plenty of radial fibrous cements (RFC)rich framestone developed in South China，and in Gantian’ao we found especially well preserved framestone reef outcrop．Base on the lithofacies and biological community analysis，we divided it to three stages：through all the history Peronidellais the dominant sponge in reef building，in stage 1 micrite framestone Peronidella and Imbricatocoelia are the dominant sponge，in stage 2 Peronidella and Guangxinella are the dominant sponge，however in stage 3 Polycystocoelia became the dominant sponge in reef building．In all three stages，the Sclerosponge is very rare here，compared to the reef in Longlin， Guangxi．The ecosystem is different to Ziyun’s reef even though it is so close．The encrustation in here is mainly Archaeolithoporella，the same as other reefs in South China at this time． By studying the history of the framestone here，especially the radial fibrous cements (RFC)．Per δ ¹³ C and δ ¹⁸ O isotope data we found that RFC’s contemporary temperature is as high as 37．86℃，we prefer to infer that RFC is an indication of high temperature marine water that incurred the accelerated process of calcite’s saturation and the RFC rich framestone is a symbol of hostile seawater，as well as the last phase of a reef ecosystem．

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