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在开展 1∶2 5万《康西瓦》、《岔路口》等四幅区域地质调查过程中 ,在岔路口及鸡冠石一带相继发现了侏罗纪基—酸性火山岩及发育完好的礁灰岩、硅质岩。依据灰岩中广泛发育的鲕粒构造、生物碎屑灰岩及礁灰岩 ,初步确定龙山组为一套滨—浅海台地相碳酸盐岩 ;通过构造环境分析 ,针对侏罗系龙山组中发育大量的基性火山岩 ,对前人认为是前陆盆地构造环境的观点提出质疑 ,并依据岩石组合、沉积相 ,结合该套地层呈大规模带状展布的特征 ,认为其形成于伸展构造环境。
During the geological survey of 4 areas of 1: 250,000 Kangxiwa and Forkroads, Jurassic-acidic volcanic rock and well-developed reef limestone were discovered successively at the fork and Jiguanshi area. rock. According to the oolitic structure, bioclastic limestone and reef limestone widely developed in the limestone, the Longshan Formation was initially identified as a set of coastal-shallow marine platform carbonates. According to the tectonic environment analysis, A large number of basic volcanic rocks are developed to challenge the previous viewpoints of the tectonic setting of the foreland basin. Based on the rock assemblage and sedimentary facies, combining with the characteristics of large-scale belt-like distribution of this set of strata, it is considered that they are formed in extensional structures surroundings.