Neogene-Holocene rift propagation in central Tanzania: Morphostructural and aeromagnetic evidence from the Kilombero area
Neogene-Holocene rift propagation in central Tanzania: Morphostructural and aeromagnetic evidence from the Kilombero area
复制标题
坦桑尼亚中部新近纪-全新世裂谷传播：来自基隆贝罗地区的地貌构造和航磁证据
DOI：
10.1130/b25202.1
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发表时间：
2004
影响因子：
4.9
通讯作者：
A. Mruma
中科院分区：
文献类型：
--
作者：
B. Gall;L. Gernigon;J. Rolet;C. Ebinger;R. Gloaguen;O. Nilsen;H. Dypvik;B. Deffontaines;A. Mruma
根据实地研究，再加上来自坦桑尼亚中部的遥感和航磁数据，该地区的显生宙构造历史可以得到发展，并置于更广泛的裂谷背景下。这项工作的主要贡献是识别了东部裂谷或肯尼亚裂谷南端400公里以外地区的裂谷形态。最突出的裂谷构造出现在Kilombero地区，由大量隆起的基底块体组成，向西由一个向东的半地堑包围，其中可能包含6-8公里的沉积地层。地貌特征和河流排水异常表明，全新世/新近纪变形既发生在裂谷平行断裂上，也发生在横向断裂上，这与若干斜向断裂的发震特征相一致。现今基隆贝罗伸展省的裂谷格局是新近系—全新世断裂对早期（卡鲁）裂谷盆地的完全叠加。Kilombero裂谷带被认为是通过一个活跃的横向断裂带向北连接到东部裂谷的中央裂谷臂（Manyara）。该裂谷模型表明，早期裂谷沿元古代基底弱带（N140°E）和更早的Karoo裂谷构造（南北）在坦桑尼亚中部的冷强岩石圈内传播。还设想了基隆贝罗裂谷带与马拉维湖裂谷更南的最终结构连接，这应该意味着坦桑尼亚克拉通以南东非裂谷系统的东部和西部分支的空间连接。
Based on field studies supplemented by remote sensing and aeromagnetic data from central Tanzania, a Phanerozoic structural history for the region can be developed and placed in a broader rift context. The major contribution of this work is the recognition of rift morphology over an area lying 400 km beyond the southern termination of the Eastern, or Kenya, Rift. The most prominent rift structures occur in the Kilombero region and consist of a wide range of uplifted basement blocks fringed to the west by an east-facing half-graben that may contain 6–8 km of sedimentary strata. Physiographic features and river drainage anomalies suggest that Holocene/Neogene deformation occurs along both rift-parallel and transverse faults, in agreement with the seismogenic character of a number of oblique faults. The present-day rift pattern of the Kilombero extensional province results from the complete overprinting of an earlier (Karoo) rift basin by Neogene- Holocene faults. The Kilombero rift zone is assumed to connect northward into the central rift arm (Manyara) of the Eastern Rift via an active transverse fault zone. The proposed rift model implies that incipient rifting propagates throughout the cold and strong lithosphere of central Tanzania following Proterozoic basement weakness zones (N140°E) and earlier Karoo rift structures (north-south). An eventual structural connection of the Kilombero rift zone with the Lake Malawi rift further south is also envisaged and should imply the spatial link of the eastern and western branches of the East African Rift System south of the Tanzanian craton.