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本区地质早已引起许多研究者的注意。在1960——1961年,作者有机会在本区研究了一些剖面,现根据化石资料并结合岩相与构造分析,分本区地层为如下的群与组(自下而上): 1.结晶岩群广泛地分布于本区东北部,其年龄可能为前寒武纪。 2.西汉水群(D_2)又为分三个组(自上而下) 3).杜家河组(类複理石建造) 2).新集子组(碳酸岩建造) 1).麻沿河组(矽质板岩建造) 在杜家河组中曾找到Stringocephalus Obesus Grabau等,在新集子组中找到Atrapa Sp,其时代应属吉维新期(D_2~2),麻沿河组中未发现任何化石,其时代难肯定。 3.大草滩群(D_3)可再分为两个组(自上而下) 2)磨峪沟组由页岩与砂岩组成,含Leptophloeum rhombicum Dawson等。 1)十八盘山组全由纯净石英岩组成。就化石特点来看,上述两组属弗拉斯期(D1/3),在岩性特征上,具有磨拉石特点。 4.木寨岭群本群分布在西汶水群与大草滩群之间,从岩性特点上与相鄰地区比较,知其时代属中石炭世。木寨岭群形成于北秦岭冒地槽迴返后的新凹陷中, 北秦岭冒地槽由此向东即为前寒武纪变质岩系所组成的秦岭地轴所封闭。
The geology of this area has already attracted the attention of many researchers. From 1960 to 1961, the authors had the opportunity to study some sections in this area. Based on the fossil data and combining lithofacies and tectonic analysis, the sub-region strata are the following groups and groups (bottom-up): 1. Crystallization Rock masses are widely distributed in the northeastern part of this area and their age may be Precambrian. 2. West Han water group (D_2) is subdivided into three groups (top-down) 3) Dujiahe Formation (class of flysch) 2) Xinji Subgroup (carbonate rock formation) 1) The Yanhe Formation (Silicate Slate Construction) has been found in the Dujihe Formation. Stringocephalus Obesus Grabau et al., Atrapa Sp was found in the Xinji Sub-Formation, and its age should belong to the JIWEI (D_2 ~ 2) In the absence of any fossils, its era is difficult to determine. 3. The group of large turfgrass (D_3) can be subdivided into two groups (top to bottom). 2) The Moguanggou Formation consists of shale and sandstone, including Leptophloeum rhombicum Dawson and others. 1) The Eighteen Panshan Formation consists of pure quartzite. In terms of fossil features, the above two groups belong to the Frasian period (D1 / 3), which has the characteristics of molasse on lithological characteristics. 4. Muzhai Ridge Group This group is distributed between the Sion water group and the Grandma group, from the lithological characteristics of the adjacent areas, that its era is the Carboniferous. The Muzhailing Group was formed in a new depression after the return of the gobo channel in the North Qinling Mountains. The gobo-tillage basin in the north Qinling Mountains is thus closed to the east by the Qinling axis formed by the Precambrian metamorphic rocks.