松辽盆地北部深层火山岩中缝合线的特征与成因

松辽盆地北部深层的酸性火山岩中广泛发育缝合线构造。缝合线可分为两类,一类常发育于岩性差异面或流纹面等界面处,产状受岩性界面或流纹面控制;另一类则与岩性界面无关,产状与构造裂缝相似。扫描电镜(SEM)的观察表明,缝合线的三维形态复杂多变,缝合柱的侧面具有显微滑痕特征。电子探针分析表明,火山岩缝合线中主要富集Fe,Al,K等元素,亏损Si和Na等元素,反映其主要物质组成为铁的氧化物、高岭石和钾盐等,局部含少量的碳酸盐岩。综合分析认为火山岩中的缝合线属后生成岩作用阶段的产物,与长英质矿物的溶解或蚀变有关,是本区火山岩岩性、地温场、流体场及应力场等因素共同作用的结果。

Characterisics and Origin of the Stylolites in Deep Burial Volcanic Rocks from the Northern Songliao Basin

Stylolite structure is widely distributed in deep burial acidic volcanic rocks in the northern Songliao Basin. Macroscopeically,stylolites can be divided into two groups.One group often develops along the interfaces of different rocks or fluxion planes and its shape and dip are controlled by these interfaces.The other group is related with the tectonic fissures.The results of observation by scan electronic microscope show that the stylolites have a complex spatial shape and their column-sides are characterized by micro-striations.Analysis by electronic probe indicates that the stylolites in volcanic rocks are composed of iron oxides,kaolinite and leopoldites,partially with a small amount of carbonates.Through comprehensive analysis,a conclusion can be drawn that the stylolites in volcanic rocks developed in the post-diagenetic period and are related with the dissolution of quartz and alteration of feldspar.The generation of stylolites may be controlled by the lithologic characters,ground temperature,fluid regime and ground stress.