- Draper, G; Lewis, JF
- The Amina-Maimon Schists and the Duarte Complex form two parallel metamorphic belts in central Hispaniola. They are separated by a belt of serpentinites and mafic rocks of mid-ocean ridge basalt affinity and are flanked on both sides by Cretaceous island-arc volcanic sequences. The Duarte Complex is intruded by several large tonalite plutons of Late Cretaceous to Paleocene age. The protolith of the Amina Maimon belt consists of mafic to felsic volcanic rocks, gray wackes, and carbonaceous shales. These rocks were heterogeneously deformed and metamorphosed to chlorite grade. The Duarte Complex consists mainly of chloritegrade metabasalts, but at least 10 other units have been identified, including metasediments, metatuffs, and ultramafic rocks. The grade of metamorphism varies from prehnite-pumpellyite to amphibolite facies. Trace element data on the metabasalts suggest that they were formed as part of an ocean island or seamount. We present a model in which the Duarte forms the oceanic basement of the southward-facing Hispaniola arc, and the Anima-Maimon rocks are the early volcanic and sedimentary deposits of that arc. A back-arc basin formed during Cenomanian time, which separated the Amina-Maimon deposits from the main arc. During the Campanian, or perhaps slightly earlier, a collisional event took place that closed the back-arc basin and caused a flip in the polarity of subduction from southwest facing to northeast facing. As the basin closed, the Duarte and rocks of the basin floor were thrust northeastward over the Amina-Maimon rocks, causing their deformation and metamorphism. Late Cretaceous to Eocene emplacement of the tonalite batholiths resulted from continued north-facing subduction.
- January 1, 1991
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