1983年,为编写陕西省地质志,我队构造专题组对秦岭地槽东段地区进行了系统的考察,对认识北大巴山地区的地质特征,收集到了一些新的资料。大致从牛山以南至高滩一兵房街一线以北地区,寒武系、奥陶系、志留系中,发现一系列多期碱基性、碱中性火山岩与火山碎屑岩及沉火山碎屑岩,并相应有(多期)次火山岩伴生。现简述几种主要火山岩、火山碎屑岩的特征: (一)碱基性火山碎屑岩—熔结碱玄质晶屑、岩屑凝灰岩岩石外貌呈深灰色,较致密,节理发育,断口具糙感,略显砂状。加稀盐酸有微弱反应。组分以碱玄岩岩屑为主,占72％,次有辉石类矿物晶屑,其中普通辉石10％,钛普通辉石3％,透辉石2％等。除晶屑呈不规则粒状外,岩屑大部分呈次棱角状之砂状物,粒 In 1983, in order to compile the geological records of Shaanxi Province, the project team of our team conducted a systematic investigation of the eastern section of the Qinling Gully. Some new data were collected for understanding the geological characteristics of the North Dabashan area. A series of multi-stage alkaline, alkaline-alkaline volcanic rocks and volcaniclastic rocks and volcanic rocks are found in the area north of Niushan to the north of the first Bingfang Street of Gaotan, Cambrian, Ordovician and Silurian Clastic rocks, and corresponding (multi-stage) secondary volcanic rocks associated. The characteristics of several major volcanic rocks and volcaniclastic rocks are briefly described as follows: (1) Alkaline volcaniclastic rocks - fused alkali metaxenic crusts, lithic tuffaceous rock rocks are dark gray in color and relatively dense with joint development and fracture A rough feeling, slightly sand-like. Diluted hydrochloric acid with a weak reaction. The basalts are dominated by basaltic rock cuttings, accounting for 72% of the total, with pyroxene mineral cuttings, of which 10% are pyroxenes, 3% titanium and 13% diopside. In addition to irregular grain granularity, most of the cuttings were sub-angular sand, grain