By analogy with late paleozoic orogeny in the Venezuelan Andes, Maracaibo Basin is en route to a granitic event
Postulated stages of orogeny in a continental crustal setting are:- 1. Stresses of plate convergence lead to block uplift and complementary basin subsidence. The basin fills with 12-14 km of illite-rich flysch (1km/3Ma). This about doubles the thickness of K-rich sial. 2. In situ heating of the flysch by radioactive decay provides a thermal gradient of c.35/sup 0/C/km and it is metamorphosed (pre-deformation) to greenschists facies. 3. After maximum crustal subsidence continued compression results in updoming of crust and overlying flysch. Cannibalism of flysch, cooling and mild subsidence follow; autometamorphism declines. 4. Thin deltaic-marine deposits complete basin fill over the meta-flysch. The unconformity (a span of only 5-10 Ma) is of minor import. 5. Resetting of the thermal profile of the depressed crust lags far behind that in the flysch. Parallels to the above in the Maracalbo basin fill are: -thickness (approx.11km), nature (flysch abounds), rate of deposition (c.1km/3-4Ma), thermal gradient (c.33/sup 0/C/km) and overall tesselar shape. Presence of impermeable strata in the Maracaibo Basin suggests that large-scale fluid convection is inhibited; conductive models of heat transfer can be used. Computer modeling suggests that radiogenic heat, augmented by exothermic oxidation of organic matter, and with a normal mantle heat flow will explain the autometamorphism of the flysch. Alternative orogenic models invoking pull-apart basins do not explain the great thickness of sediments and absence of volcanic activity.
- Research Organization:
- Univ. of Pennsylvania, Philadelphia (USA)
- OSTI ID:
- 6457604
- 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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SEDIMENTARY BASINS
GEOLOGIC HISTORY
GEOTHERMAL GRADIENTS
HEAT TRANSFER
OROGENESIS
VENEZUELA
COMPUTERIZED SIMULATION
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DIAGENESIS
EARTH CRUST
GEOLOGIC MODELS
GRANITES
METAMORPHISM
ORIGIN
PETROGENESIS
PLATE TECTONICS
SEDIMENTARY ROCKS
STRESS ANALYSIS
STRESSES
DEVELOPING COUNTRIES
ENERGY TRANSFER
GEOLOGIC STRUCTURES
IGNEOUS ROCKS
LATIN AMERICA
PLUTONIC ROCKS
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SIMULATION
SOUTH AMERICA
TECTONICS
TEMPERATURE GRADIENTS
580100* - Geology & Hydrology- (-1989)
580201 - Geophysics- Seismology & Tectonics- (1980-1989)