A set of pull\|apart basins were formed along the Weixi—Qiaohou right\|lateral slip shear zone of the western part of Honghe fault zone during the period from Miocene to Quaternary.A rock suite of alkaline basalt\|tr...A set of pull\|apart basins were formed along the Weixi—Qiaohou right\|lateral slip shear zone of the western part of Honghe fault zone during the period from Miocene to Quaternary.A rock suite of alkaline basalt\|trachyte\|leucite phonolite is distributed in the Pliocene basin developed in the middle and northern parts of the fault. The location of these rocks and the features of the basin indicate the close relationship between the rock suite and the strike\|slipping.. The sedimentological and chronological evidences prove that Dianxi plateau uplifted quickly in the Pliocene. We can get the information about the plutonic process of the uplift of the plateau from this alkaline rock association. There are mainly olivine\|pyroxene\|trachyandesite and biotite\|trachyte in the rock association. The rocks are often of porphyritic texture and block or semi\|directional flowage structure while the matrix is of trachytic or microcrystalline texture. The phanerocrysts are diopsidic augite, rimpylite, biotite and perthite (olivine sometimes can be seen). The matrix are made up of alkaline feldspar microcrystalline (30%～50%), short\|grained diopside (10%～15%), light\|colored volcanic glass (0～15%) and some magnetite, while feldspar microcrystalline in some rocks are arranged directionally. And there are sharp\|edged or round pyroxenite enclaves and hemicrystalline of short grained sinaite, biotite sinaite and felsic breccia in the trachyte, with good demarcation line. The pyroxenite enclaves in the trachyte are of different size, and the size of the biggest ones are 10cm or so with the characteristic of plastic yield flowing. Sinaite hemicrystalline may come from the older intrusions of Pliocene and Eocene epoch.展开更多
Meso\| and microstructural characteristics of cataclastic fault rocks developed in the Xialu chert are described. The Xialu chert represents pelagic and deep marine sediments (Middle Jurassic—Lower Cretaceous), and o...Meso\| and microstructural characteristics of cataclastic fault rocks developed in the Xialu chert are described. The Xialu chert represents pelagic and deep marine sediments (Middle Jurassic—Lower Cretaceous), and occupies the southern marginal part of the E—W trending Yarlung Zangbo suture zone. The apparent total thickness of siliceous deposits exceeds 1km. The current study is concentrated along the two measured sections, Xialu\|E and Xialu\|W. The Xialu\|E section is composed mainly of red chert associated with reddish purple siliceous mudstone and greenish gray mudstone. The beds steeply dip north or south. The 45m section studied is divided into three units (chert unit, chert\|siliceous mudstone unit, and melange unit from north to south). They are in fault contact with each other. In the southern half of the chert unit and the northernmost of the chert\|siliceous mudstone unit, a 15m thick cohesive cataclasite zone can be defined. The cataclasites are composed of chert fragments in a fine grained matrix, and deformed with jigsaw puzzle structures. The chert\|siliceous mudstone unit is made up of four slabs of chert\|siliceous mudstone sequence. Mesoscopic duplex zones in thickness from 1 to 3m are recognized at slab boundaries. Flat and ramp structure and associated P foliations, R1 shears, Y surfaces are developed. Shear spacing range from 1 to 10cm. The slip senses are dextral strike\|slip movement along these duplex zones. The cataclasite zone is cut by the duplex zone along the southern boundary.展开更多
文摘A set of pull\|apart basins were formed along the Weixi—Qiaohou right\|lateral slip shear zone of the western part of Honghe fault zone during the period from Miocene to Quaternary.A rock suite of alkaline basalt\|trachyte\|leucite phonolite is distributed in the Pliocene basin developed in the middle and northern parts of the fault. The location of these rocks and the features of the basin indicate the close relationship between the rock suite and the strike\|slipping.. The sedimentological and chronological evidences prove that Dianxi plateau uplifted quickly in the Pliocene. We can get the information about the plutonic process of the uplift of the plateau from this alkaline rock association. There are mainly olivine\|pyroxene\|trachyandesite and biotite\|trachyte in the rock association. The rocks are often of porphyritic texture and block or semi\|directional flowage structure while the matrix is of trachytic or microcrystalline texture. The phanerocrysts are diopsidic augite, rimpylite, biotite and perthite (olivine sometimes can be seen). The matrix are made up of alkaline feldspar microcrystalline (30%～50%), short\|grained diopside (10%～15%), light\|colored volcanic glass (0～15%) and some magnetite, while feldspar microcrystalline in some rocks are arranged directionally. And there are sharp\|edged or round pyroxenite enclaves and hemicrystalline of short grained sinaite, biotite sinaite and felsic breccia in the trachyte, with good demarcation line. The pyroxenite enclaves in the trachyte are of different size, and the size of the biggest ones are 10cm or so with the characteristic of plastic yield flowing. Sinaite hemicrystalline may come from the older intrusions of Pliocene and Eocene epoch.
文摘Meso\| and microstructural characteristics of cataclastic fault rocks developed in the Xialu chert are described. The Xialu chert represents pelagic and deep marine sediments (Middle Jurassic—Lower Cretaceous), and occupies the southern marginal part of the E—W trending Yarlung Zangbo suture zone. The apparent total thickness of siliceous deposits exceeds 1km. The current study is concentrated along the two measured sections, Xialu\|E and Xialu\|W. The Xialu\|E section is composed mainly of red chert associated with reddish purple siliceous mudstone and greenish gray mudstone. The beds steeply dip north or south. The 45m section studied is divided into three units (chert unit, chert\|siliceous mudstone unit, and melange unit from north to south). They are in fault contact with each other. In the southern half of the chert unit and the northernmost of the chert\|siliceous mudstone unit, a 15m thick cohesive cataclasite zone can be defined. The cataclasites are composed of chert fragments in a fine grained matrix, and deformed with jigsaw puzzle structures. The chert\|siliceous mudstone unit is made up of four slabs of chert\|siliceous mudstone sequence. Mesoscopic duplex zones in thickness from 1 to 3m are recognized at slab boundaries. Flat and ramp structure and associated P foliations, R1 shears, Y surfaces are developed. Shear spacing range from 1 to 10cm. The slip senses are dextral strike\|slip movement along these duplex zones. The cataclasite zone is cut by the duplex zone along the southern boundary.
