Geochemistry and Geochronology of the Southern Caribbean–Northern Venezuela Plate Boundary

摘要: The geochemistry and geochronology of the igneous rocks from Venezuelan islands in southern Caribbean, Netherlands Leeward Islands, Caribbean Mountains northern Venezuela were studied an effort to test plate tectonics models for evolution that part region. continental platform north is underlain by metamorphic complex crops out on islands. older (lower upper greenschist facies) are similar those found Mountains. These intruded basic granitic andesitic basaltic volcanic during Early Cretaceous early Tertiary time. Geochemically, can be divided into two suites, a calc-alkaline suite consisting quartz diorite, granodiorite, trondhjemite, granite, olivine ocean-floor tholeiitic gabbro, diabase, lamprophyre, orthoamphibolite. affinity shown high Al 2 O 3 K O, low MgO TiO contents. content increases southward toward Fe /MgO ratios, Sr contents, K/Rb ratios. K-Ar age determinations these show rock oldest, which confirms field relations, ranging between 114 m.y. 130 (Early Cretaceous). ages range 30 84 (Late Oligocene). interpreted represent Late Cretaceous–early time intrusion later metamorphism also support late Eocene–Oligocene erogenic event resulted present structural configuration central A dacite Carupano area (Araya-Paria Peninsula) yielded 5 m.y., or Pliocene, youngest evidence activity Venezuela. possibly related younger province Lesser Antilles. Our data hypothesis Aves Ridge represents presently inactive arc prior Antilles arc.