THE PETROLOGIC CHARACTERISTICS OFJ_3~(3o) VOLCANIC ROCKS IN LENCHA BASIN AND THE COMPARISONS WITH PORPHYROCLASTIC LAVA IN XIANGSHAN
Liu Xiaodong, Ma Lijun (Center of Modern Analysis)
Porphyroclastic lava, which is widelyspread in Southeast China, is a kind of acidic(intermedium-acidic)volcanics with special petrological features. Lencha basin is a large yolcanic fault basin located in North Guangdong prgvince. This basin, consists primarily of J_3~(3o) volcanic rock. Th systematic study of the petrology and the comparisons with porphyroclastc lava in xiangshan show( that the rocks have) the basic characteristics of porphyroclastic lava as follow: (1) the rocks have the typomorphic porphyroclastic texture and the over growth texture surrounding porphyritic crystals; (2) the rock body shows variation in texture from outer part toinner (3) the chemical comporsition, mineralogical features inclusion features inminerals and the features of rock debris are similar to the announced porphyroclastic lava in xiangshan and in other places; (4) the rocks lie in the same tectonic zone as those porphyroclastic lava in Fujian province, Therefore, the J_3~(3o) volcanic rocks in Lencha basin can be classified as porphyroclastic lava, and the rocks are possibly favourable for uranium mineralization in Lencha.