Lithospheric Structure Beneath the Alboran Basin: Results from 3D Gravity Modeling and Tectonic Relevance
Lithospheric Structure Beneath the Alboran Basin: Results from 3D Gravity Modeling and Tectonic Relevance
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阿尔博兰盆地下方的岩石圈结构：3D 重力模型和构造相关性的结果
DOI：
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发表时间：
2000
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影响因子：
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通讯作者：
J. Soto
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作者：
M. Torné;Manel Fernàndez;M. Comas;J. Soto
三维重力模拟结合综合热流和高程模型进行映射出的地壳和岩石圈地幔厚度在阿尔沃兰盆地，在地中海最西部。“沉积物”校正的布格异常已经使用深度到基底图和密度从测井和地震数据确定。从沉积物校正的布格异常中去除岩石圈底部的重力效应，得到“地壳”布格异常，并将其反演为地壳厚度。由此产生的岩石圈结构进一步约束下的假设当地的等值线高程数据。剩余高程异常较低（平均±100 m），表明该区处于局部等深线，尤其是中、长波地形特征。地壳厚度的变化范围从Betic和Rif链之下的36公里到Alboran海盆最东部之下的12公里，在向南巴利阿里海盆的过渡中。在阿尔沃兰西部，莫霍面的深度相当稳定，为1018公里，向直布罗陀海峡急剧加深，深度达30-32公里。岩石圈底部从直布罗陀海峡的140 km深度变浅到最东端的阿尔沃兰海的<45 km深度。岩石圈减薄穿透到伊比利亚边缘的东南侧，横切贝蒂斯链中部和东部的地形高点。我们的研究结果有利于地幔脱层所产生的拆离和随后剥离的岩石圈地幔，而不是对流去除岩石圈地幔无论是造山带的崩溃或拆离和下沉的岩石圈板。
A three-dimensional gravity modeling combined with integrated heat flow and elevation modeling is conducted to map out the crustal and lithospheric mantle thickness in the Alboran Basin, in the westernmost Mediterranean. A “sediment”-corrected Bouguer anomaly has been derived using a depth-to-the-basement map and densities determined from well logs and seismic data. The gravity effect of the base of the lithosphere has been removed from the sediment-corrected Bouguer anomaly to obtain a “crustal” Bouguer anomaly, which has been inverted for crustal thickness. The resulting lithospheric structure is further constrained by elevation data under the assumption of local isostasy. The low residual elevation anomalies obtained (±100 m in average) suggest that the area is in local isostasy, particularly the medium- and long-wavelength topography features. Variations in crustal thickness range from 36 km underneath the Betic and Rif Chains to <12 km beneath the easternmost part of the Alboran Sea Basin, in the transition to the South Balearic Basin. In western Alboran the Moho lies at a rather constant depth of ∼18 km, deepening sharply toward the Gibraltar Strait down to 30–32 km. The base of the lithosphere shallows from 140 km depth in the Gibraltar Strait to <45 km depth in the easternmost Alboran Sea. Lithospheric thinning penetrates to the southeastern side of the Iberian margin crosscutting topographic highs of the central and eastern Betic Chain. Our results favor mantle delamination produced by detachment and subsequent peeling away of the lithospheric mantle rather than convective removal of the lithospheric mantle either by orogenic collapse or detachment and sinking of a lithospheric slab.