The major features of the crustal structure in north-eastern Venezuela from deep wide-angle seismic observations and gravity modelling
The major features of the crustal structure in north-eastern Venezuela from deep wide-angle seismic observations and gravity modelling
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DOI：
10.1016/j.tecto.2004.12.018
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发表时间：
2005-04
期刊：
影响因子：
2.9
通讯作者：
M. Schmitz;A. Martins;C. Izarra;M. Jacome;J. Sánchez;V. Rocabado
中科院分区：
文献类型：
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作者：
M. Schmitz;A. Martins;C. Izarra;M. Jacome;J. Sánchez;V. Rocabado
委内瑞拉位于南美大陆和加勒比海板块之间的板块边界地带。从安第斯山脉到巴里亚湾的走滑断层系统提供了2厘米/年的相对运动。内陆山脉是一条中等高度的山脉，将东方盆地与加勒比海隔开。在南部，奥里诺科河以南的瓜亚纳地盾以前寒武纪岩石为主。该地区的深广角地震测量结果是在1998年(ECOGUAY)瓜亚纳盾(ECOGUAY)和2001年(ECCO)东方盆地实地活动期间获得的。总的地壳厚度从瓜亚纳盾下的45公里减少到奥里诺科河下的39公里，以及东方盆地中心靠近El Tigre的36公里。平均地壳速度也从6.5km/S降至5.95km/km2。获得了有关东方盆地内部速度分布的详细信息。速度最高处为2.2公里/S，下部为4.5公里/S至4公里，最大深度为13公里，最大深度为5.9公里/S，被解释为沉积盆地的底部。重力模型证实了从地震数据中得出的构造。盆地沉积厚度的离散增加可能与白垩纪被动边缘阶段或早期伸展阶段的伸展过程有关。
Venezuela is located on the plate boundary zone between the South American continent and the Caribbean plate. A relative movement of 2 cm/year is accommodated by a system of strike–slip faults running from the Andes to the Gulf of Paria. The Interior Range, a moderate-height mountain range, separates the Oriental Basin from the Caribbean. To the south, predominantly Precambrian rocks are outcropping in the Guayana Shield south of the Orinoco River. Results of deep wide-angle seismic measurements for the region were obtained during field campaigns in 1998 (ECOGUAY) for the Guayana Shield and in 2001 (ECCO) for the Oriental Basin. The total crustal thickness decreases from 45 km beneath the Guayana Shield, to 39 km at the Orinoco River, and 36 km close to El Tigre, in the center of the Oriental Basin. The average crustal velocity decreases in the same sense from 6.5 to 5.95 km/s. Detailed information was obtained on the velocity distribution within the Oriental Basin. Velocities are as low as 2.2 km/s for the uppermost 2 km, 4.5 km/s down to 4 km in depth, and a maximum depth of 13 km was derived for material with seismic velocities up to 5.9 km/s, interpreted as the base of the sedimentary basin. A gravimetric model confirms the structures derived from the seismic data. Discrete increases in sedimentary thickness along the basin may be associated to extension processes during the passive margin phase in the Cretaceous, or during earlier extension phases.