Circulation of high pressure blocks in subduction complexes: some insights from northern Hispaniola
Detailed mapping in the Rio San Juan Complex (RSJC) and reconnaissance investigations in the Samana peninsula, in North Hispaniola, have determined the characteristics of a Cretaceous blueschist/eclogite melange. In the RSJC, the melange has a mafic greenschist matrix which appears to be part of a larger, coherent greenschist terrane, which varies in composition and includes mafic and quartz feldspathic types interbedded in a sedimentary protolith. Of the many lithologies present in the melange, the most common are original gt-px and gt-hbl schist, both of which have been strongly overprinted by a blueschist facies metamorphism. The blocks also have a rind of coarse grained actinolite surrounded a second rind of actinolite + chlorite + fuchsitic (cr-rich) mica. The authors follow Moore in suggesting that the rind formed by contact with serpentinite at depth. They suggest instead that rind formation and block exhumation were by diapirism and/or corner flow of serpentinite. Limited isotopic evidence suggests that the blocks area about 90 m.y. old. Stratigraphic evidence indicates that the deeper levels of the coherent metamorphic terrane was eroded by Paleocene time (65 m.y. b.p.). Thus, the complete cycle of exhumation of blocks from greater than 30km., their incorporation into trench-fill sediments, burial of the coherent terrane and subsequent erosion of this terrane took place in about 25 m.y.. Since the erosion of the coherent terrane must have occupied the greater part of this time period (about 20 m.y.), then both burial and exumation took place in only a few million years.
- Research Organization:
- Florida International Univ., Miami (USA)
- OSTI ID:
- 6612578
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HISPANIOLA
PLATE TECTONICS
SUBDUCTION ZONES
SCHISTS
GEOLOGIC HISTORY
ISOTOPE DATING
CRETACEOUS PERIOD
GEOLOGIC FAULTS
GEOLOGIC MODELS
MAPPING
STRATIGRAPHY
AGE ESTIMATION
GEOLOGIC AGES
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOLOGY
GREATER ANTILLES
ISLANDS
MESOZOIC ERA
METAMORPHIC ROCKS
ROCKS
TECTONICS
WEST INDIES
580201* - Geophysics- Seismology & Tectonics- (1980-1989)
580100 - Geology & Hydrology- (-1989)