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931.
J. L. Granja Bruña A. Muñoz-Martín U. S. ten Brink A. Carbó-Gorosabel P. Llanes Estrada J. Martín-Dávila D. Córdoba-Barba M. Catalán Morollón 《Marine Geophysical Researches》2010,31(4):263-283
The Muertos Trough in the northeast Caribbean has been interpreted as a subduction zone from seismicity, leading to infer
a possible reversal subduction polarity. However, the distribution of the seismicity is very diffuse and makes definition
of the plate geometry difficult. In addition, the compressive deformational features observed in the upper crust and sandbox
kinematic modeling do not necessarily suggest a subduction process. We tested the hypothesized subduction of the Caribbean
plate’s interior beneath the eastern Greater Antilles island arc using gravity modeling. Gravity models simulating a subduction
process yield a regional mass deficit beneath the island arc independently of the geometry and depth of the subducted slab
used in the models. This mass deficit results from sinking of the less dense Caribbean slab beneath the lithospheric mantle
replacing denser mantle materials and suggests that there is not a subducted Caribbean plateau beneath the island arc. The
geologically more realistic gravity model which would explain the N–S shortening observed in the upper crust requires an overthrusted
Caribbean slab extending at least 60 km northward from the deformation front, a progressive increase in the thrusting angle
from 8° to 30° reaching a maximum depth of 22 km beneath the insular slope. This new tectonic model for the Muertos Margin,
defined as a retroarc thrusting, will help to assess the seismic and tsunami hazard in the region. The use of gravity modeling
has provided targets for future wide-angle seismic surveys in the Muertos Margin. 相似文献
932.
933.
Mayra C. Robles-Montes Guillermo Martínez-Flores Michael K. Faught Enrique H. Nava-Sánchez 《Geoarchaeology》2024,39(2):106-121
When the first Americans inhabited the area now known as Isla Espiritu Santo, around 12.5 and 6 ka, the sea level continuously rose. This resulted in the loss of the coastal territory and the retreat of the human population further inland. Part of the archaeological evidence of this period currently lies over the seafloor and under the seabed. Therefore, reconstructing paleoshorelines is a necessary first step toward submerged precontact archaeology and a broad understanding of the spatial context in which those human populations interacted and how the landscapes changed. Isla Espiritu Santo is of prehistoric importance as it contains numerous Paleocoastal tradition sites as early as ~12,400 Cal B.P. This research aims to reconstruct the changing shoreline positions as sea levels rose around Isla Espiritu Santo between 12.5 and 6.5 ka. We apply numerical modeling to map digital elevation models at 1 ka intervals by estimating the changes in the morphology of the seafloor according to the deposition rates and global sea-level curve. The results show the evolution of coastal morphology and paleoshoreline's position. Three primary geoforms are proposed: (1) coastal plains, (2) tombolo, and (3) a coastal lagoon–island barrier system. This also offers insights into the physical aspect of submerged prehistoric landscapes and the possible resource exploitation options of early societies. In this research, the reconstruction of submerged landscapes seeks to contribute to the long-term goal of locating submerged precontact sites. 相似文献