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西藏甲马弧内盆地晚侏罗世海绵礁属于台地边缘礁 ,呈近EW向展布 ,延伸长达 4～ 5km ,宽约 50m ,建筑在叶巴期火山岩浆弧的正地形上。由北向南展示出礁坪相到礁核相再到礁前斜坡相的侧向演变。其中礁核相主要由海绵骨架岩、障积岩和粘结岩等构成。海绵礁可分为并进礁和中止礁 2种类型 ,发育至少 6套垂向上相互迭叠的礁旋回。研究表明 ,甲马矿区海绵礁形成的关键因素是海平面变化 ,其主体的发育与海平面相对上升同步。
The Late Jurassic sponge reef in the Jiama basin, Jiama, Tibet, belongs to the marginal reef of the platform and exhibits near EW distribution with an extension of 4 ~ 5km and a width of 50m. It is built on the positive terrain of the Yeba phase volcanic magma arc. From north to south, the lateral evolution of the reef phase to the reef core phase to the reef slope phase is demonstrated. Reef nuclear phase mainly by the sponge skeleton rock, barrier rock and bond rock and other components. Sponge reefs can be divided into two types of reefs and reefs, with at least 6 sets of reefs vertically overlapping each other. The research shows that the key factor for the formation of sponge reefs in Jiama mine area is the change of sea level, and the development of its main body is synchronous with the relative rise of sea level.