相山及邻区七个火山盆地火山岩岩性特征及成因探讨

本文研究赣杭构造带西南端相山及其邻区7个火山盆地主体岩石的特征和成因,从地质产状、岩性、岩石化学等方面做了论述。采用了红外光谱、矿物包裹体、高温实验等研究方法,探讨了岩石的形成机理。相山主体岩石是一种成因特殊的火山碎屑(斑)熔岩,即岩颈碎屑熔岩和岩流碎屑熔岩。相山等火山盆地主体岩石边部的塑性岩屑不是熔离成因,而是由火山喷发作用形成的。火山碎屑熔岩中的斜长石牌号变化大,钾长石主要是低透长石,表明岩石的形成具有高温特征。不同岩石相的矿物中的熔融包裹体有明显的形态标型。碎眉熔岩中的石英碎斑结构,主要是高温热炸裂成因的。7个火山盆地中的主体岩石可划分两大类:相山、玉华山和礼陂火山盆地的主体岩石是火山碎屑熔岩;高家、林家、谙源和谭港火山盆地的主体岩石是弱熔结凝灰岩。

APPROACH TO THE LITHOLOGIC FEATURES AND THE ORIGIN OF THE YOLCANIC ROCKS IN XIANGSHAN AND ITS ADJACENT AREAS

This paper makes a study of the features and the origin of the main rocks in the seven volcanic basins of Xiangshan and its adjacent areas, and makes a discussion of them form geological occurrences, lithologic features, petrochemistry. Several methods, such as infrabed spectrum, mineral inclusions, diagenetic experiment and electronic computation, have been used to probe into rock-orming mechanism and denomination. 1. Xiangshan main rock is not a lava or subvolcanic rock or welded tuff, nor is a normal volcanic clastic rock. But it is a kind of volcanic clastic lava such as plug clastic lava and rockflowage clastic lava. 2. plastic detritus on the side of the main rocks in Xiangshan and other volcanic basins are not one result of the action by liquation but formed fron?the volcanic eruption. 3. By precisely detecting the feldspar in volcanic clastic lava, it has been found that the variety number range of plagioclase in the rock is large and potash feldspar chiefly is low sanidine. The feldspar in volcanic clastic lava has typomorphic significance for its formation environment. 4. In the volcanic basins in Xiangshan and its adjacent areas, the fusion inclusions have apparent morphological type in the minerals of different litho?facies. 5. It has been proved on the basis of the high temperature rock-forming experiment that the formation mechanism of the quartz mortar texture in the clastic lava is originated from heat explosion under high temperature. 6. The seven volcanic basins can be classified into two main types. One is the rhyovolcanic clastic lava in Xiangshan, Yuhuashan and Lipi volcanic basins, the other is that the main rocks in Gaojia,linjia, Anyuan and Tangang volcanic basins are weak ignimbrite.