Deep structures in southern Italy. Evidences from the gargano-pantelleria seismic refraction experiment (1971)
Deep structures in southern Italy. Evidences from the gargano-pantelleria seismic refraction experiment (1971)
复制标题
意大利南部的深层结构。
DOI：
--
复制
发表时间：
2007
期刊：
影响因子：
--
通讯作者：
G. Caielli
中科院分区：
文献类型：
--
作者：
G. Biella;R. Franco;E. Marsella;G. Caielli
根据关于近第勒尼安带和亚平宁山脉地壳结构的新地质假说，我们尝试重新解释 1971 年沿着从第勒尼安海深海平原延伸到普利亚台地、贯穿整个亚平宁山脉的一条地震折射实验。在本文中，我们提出了第勒尼安南大陆边缘从挤压构造演化到伸展构造的综合地壳模型。地震数据集与地面地质数据和重力建模相结合和约束，提供了三层岩石圈模型。在速度模型的西南半部，穿过第勒尼安边缘，上地壳的特征是横向速度和厚度变化，这是由第勒尼安后弧盆地的开口控制的从海洋到过渡到减薄大陆地壳的转变引起的。接收器集合中存在来自下地壳顶部的相当清晰的广角反射（PiP），限制了上地壳的厚度。下地壳层的厚度和速度由显着的 PmP 相定义，这些相广泛地穿过该层。仅在记录剖面的少数痕迹上观察到 Pn 首次到达，并解释了“第勒尼安”上地幔速度为 7.8 km/s。“第勒尼安莫霍面”向东北方向的延伸受到在一些接收器集合上观察到的 PmP 阶段的限制，其中也证明了后期阶段。我们将这些迟到的事件解释为下降的亚得里亚海板块的地壳/地幔边界的反射阶段。加尔加诺站观测到的 Pn 相是整个数据集中更清晰和完整的，将亚得里亚海上地幔速度限制为 7.9 公里/秒，也与第勒尼安期上地幔 7.8 公里/秒一致。使用布格重力异常对根据广角数据集开发的地壳模型进行了独立测试。地壳速度模型用作重力建模的直接输入。作为与大规模重力异常（平均网格尺寸为 3x3 km）相关的可用数据汇编，考虑到 Vp 横向变化，仅对三层（上地壳、下地壳、上地幔）进行了建模。
In the light of new geological hypothesis on the crustal structure under the peri-Tyrrhenian belt and the Apennines chain we tried a reinterpretation of a seismic refraction experiment which was carried out in 1971 along a line stretching from the Tyrrhenian sea bathyal plain to the Apulia platform, throughout the Apenninic chain. In this paper we present an integrated crustal model across the southern Tyrrhenian continental margin that evolved from compressional to extensional tectonics. The seismic data set combined and constrained with surface geologic data and gravity modeling provides a three layers lithospheric model. In the Southwestern half of the velocity model, across the Tyrrhenian margin, the upper crust is characterized by lateral velocity and thickness variability caused by the transition from oceanic to transitional to thinned continental crust controlled by the opening of the Tyrrhenian back arc basin. Quite clear wide angle reflections (PiP) from the top of the lower crust are present in the receiver gathers, constraining the thickness of the upper crust. Thickness and velocity of the lower crustal layer are defined by prominent PmP phases which travel extensively through this layer. Pn first arrivals are observed only on few traces of the record sections and account for a «Tyrrhenian » upper mantle velocity of 7.8 km/s The prolongation of the «Tyrrhenian Moho» northeastward is constrained by PmP phases observed on some receiver gathers, where later phases are also evidenced. We interpreted these late arrivals as reflected phases of the crust/mantle boundary of the downgoing Adriatic slab. Pn phases observed on the Gargano stations, the more clear and complete of the entire data set, constrain an Adriatic upper mantle velocity of 7.9 km/s and are also consistent with a Tyrrhenian upper mantle of 7.8 km/s. The crustal model developed from the wide-angle data set was indipendently tested using Bouguer gravity anomalies. The crustal velocity model was used as a direct input for the gravity modeling. Being the available data compilation related to large scale gravity anomalies (average grid dimension of 3x3 km), only three layers have been modeled (upper and lower crust, upper mantle), taking into account the Vp lateral variations.