东非被动大陆边缘盆地近年来发现了一系列大气田，主要分布于鲁武马盆地，其可采储量达3.8×1012 m3。盆地经历了卡鲁裂谷期、马达加斯加裂谷期和马达加斯加漂移期等3期构造演化。其中，马达加斯加裂谷期形成下侏罗统—中侏罗统湖相滨浅海相烃源岩，于早白垩世进入生油门限，晚白垩世达到生油高峰，渐新世进入生气窗。受马达加斯加漂移期东非陆上断裂系统活动影响，大量富砂沉积物以块体搬运和深海滑塌方式向深水区堆积，形成了盆地内面积广、厚度大、岩性相对均一且物性良好的超大型深水重力流沉积砂体；漂移期海相泥页岩则为良好的区域性盖层。东非陆上早期隆升和三角洲进积作用使鲁武马盆地形成重力滑动和盐底辟构造，渐新统—上新统内形成东非被动陆缘正断层带(EANFZ)和逆冲断层带(EATFZ)，下伏中—下侏罗统烃源岩生成油气沿正断层和深水区逆冲断层向上运移，聚集于构造岩性地层、构造圈闭中，形成大气田。

Many giant gas fields, concentrated in the Rovuma Basin of the East Africa passive margin basins, were discovered in recent years with a total recoverable reserves up to 3.8 trillion cubic meters. The Rovuma Basin has gone through three stages of tectonic evolution, i.e. the Karoo rift, Madagascar rift and Madagascar drift. The LowerMiddle Jurassic lacustrine and shallow sea source rocks formed in the Madagascar rift period, and came to the oil window, the peak of oil generation and the gas window, in the Early Cretaceous, the Late Cretaceous and the Oligocene, respectively. Affected by the East Africa onshore faults during the Madagascar drift period, massive sandrich sediments accumulated towards the deep water region by way of block transport and deep water sliding. It formed a super giant deepwatergravityflow sandbody, wide and thick, with relatively uniform lithology and favorable physical property within the basin. The marine mudstone during the Madagascar drift period provided a good regional overlying strata. The early uplift onshore East Africa and delta progradation led to the formation of gravity sliding and salt diapir within the Rovuma Basin, and subsequently the East Africa normal fault zone (EANFZ) and the East Africa thrust fault zone (EATFZ), between the Oligocene and Pliocene. As a result, hydrocarbons from the underlying LowerMiddle Jurassic source rocks migrated upward along the normal and deep water thrust faults, accumulating in the structurallithologicalstratigraphy and structural traps to form the giant gas fields.<br>

基于板块构造理论，通过研究地震、地质及相关文献资料，恢复东非被动大陆边缘主要地质时期原型盆地及岩相古地理，开展盆地结构构造特征及其沉积充填差异分析，结合已发现的15个油气藏解剖，建立3种成藏模式，探讨该区有利成藏组合及下一步勘探方向。东非被动大陆边缘盆地群历经晚石炭世—三叠纪卡鲁（Karoo）期陆内夭折裂谷、侏罗纪陆内—陆间裂谷及白垩纪以来的被动大陆边缘盆地3个原型阶段，各个盆地裂谷层系普遍发育，受拗陷期沉积充填厚度大小影响，形成“断陷型”、“断坳型”和“三角洲改造型”3类被动陆缘盆地：“断陷型”拗陷期沉积最大厚度小于3 000 m，形成“单源-构造型”成藏模式，勘探方面以寻找裂谷层系顶部发育的大型构造类圈闭为主；“断坳型”拗陷期沉积最大厚度大于5 000 m，形成“双源-双组合型”成藏模式，勘探方面以上、中斜坡大型滑动—滑塌—碎屑流沉积砂体为目标；“三角洲改造型”拗陷期沉积最大厚度大于6 000 m且发育高建设性三角洲，从岸向海形成独特生长断裂、泥底辟、逆冲推覆、前渊缓坡四大构造带，形成“三源-多组合型”成藏模式，其四大构造带均可形成大型油气田。图8表2参27

马达加斯加是非洲东南部岛国,成矿地质条件有利,矿产资源丰富。该国属非洲克拉通组成部分,以前寒武纪构造—岩浆—变质杂岩为主,西部及东、西海岸带分布少量晚古生代—中生代泥砂质碎屑岩—碳酸盐岩和中新生代火山—沉积岩系。该国矿产主要分布于前寒武纪地质体中,少数沉积型矿产赋存于晚古生代—新生代地层内,主要矿产有铁、铬、钛、镍、钴、铝、金、石墨、煤及宝石等。