Logotipo del repositorio

Artículos científicos

URI permanente para esta colecciónhttp://10.0.96.45:4000/handle/11056/17882

Examinar

Examinando Artículos científicos por Materia "AMBIENTE MARINO"

Seleccione resultados tecleando las primeras letras
Mostrando 1 - 2 de 2
  • Miniatura
    Ítem
    Effect of subducting sea-floor roughness on fore-arc kinematics, Pacific coast, Costa Rica
    (Geological Society of America, 1998-05-01) Fisher, Donald M.; Gardner, Thomas W.; Marshall, Jeffrey S.; Sak, Peter B.; Protti, Marino
    Fault kinematics and uplift in the Costa Rican fore arc of the Middle America convergent margin are controlled to a large extent by roughness on the subducting Cocos plate. Along the northwest flank of the incoming Cocos Ridge, seafloor is characterized by short wavelength roughness related to northeast-trending seamount chains. Onland projection of the rough subducting crust coincides with a system of active faults oriented at high angles to the margin that segment the fore-arc thrust belt and separate blocks with contrasting uplift rates. Trunk segments of Pacific slope fluvial systems typically follow these margin-perpendicular faults. Regionally developed marine and fluvial terraces are correlated between drainages and acrossfaults along the Costa Rican Pacific coast. Terrace separations across block-bounding faults reveal a pattern of fore-arc uplift that coincides roughly with the distribution of incoming seamounts. Magnitude and distribution of Quaternary uplift along the Costa Rican Pacific coast suggests that, despite a thin incoming sediment pile, the inner fore arc shows an accumulation of mass—a characteristic that may be due to underplating of seamounts beneath the fore-arc high.
  • Miniatura
    Ítem
    Holocene forearc block rotation in response to seamount subduction, southeastern Península de Nicoya, Costa Rica
    (Geological Society of America, 2001-02) Gardner, Thomas; Marshall, Jeffrey; Merritts, Dorothy; Bee, Bhavani; Burgette, Reed; Burton, Emily; Cooke, Jennifer; Kehrwald, Natalie; Protti, Marino; Fisher, Donald; Sak, Peter
    The southeastern tip of the Penı´nsula de Nicoya, Costa Rica, on the Caribbean plate margin lies inboard of the rough bathymetric terrain on the subducting Cocos plate and along the landward projection of the convergence vector for the Fisher seamount group. The southern tip of the peninsula has nearly orthogonal coastlines and extensive, well-preserved, Holocene marine terraces,and is ideally situated to evaluate the spatial distribution of forearc deformation in response to seamount subduction. Two marine terraces that yielded 35 radiocarbon dates give information on the rates, style, and timing of deformation along 40 km of coastline. Ages range from 3.5 to 7.4 ka for a higher terrace and from 0.3 to 2.9 ka for a lower terrace. A maximum uplift rate is ;6.0 m/k.y. along the southeastern tip of the peninsula. Uplift rates decrease linearly to ,1.0 m/k.y. along both orthogonal coastlines and thus landward from the Middle America Trench and away from the line of subducting seamounts. The ;400km2 region along the tip of the peninsula can be approximated as a rotating block with an angular rotation rate of 0.028/k.y. about an axis with an azimuth of 808. Given the modern elevation and dip of the late Quaternary Cobano surface, this style of deformation is limited to a duration of 100–200 k.y. Deformation is occurring in response to seamount bypass or underplating onto the Caribbean plate margin.