By analogy with late paleozoic orogeny in the Venezuelan Andes, Maracaibo Basin is en route to a granitic event

Conference · Tue Jan 01 00:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6457604

Shagam, R; Giegengack, R F; Lutz, T M

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

Related Subjects

58 GEOSCIENCES
SEDIMENTARY BASINS
GEOLOGIC HISTORY
GEOTHERMAL GRADIENTS
HEAT TRANSFER
OROGENESIS
VENEZUELA
COMPUTERIZED SIMULATION
DEPOSITION
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
ROCKS
SIMULATION
SOUTH AMERICA
TECTONICS
TEMPERATURE GRADIENTS
580100* - Geology & Hydrology- (-1989)
580201 - Geophysics- Seismology & Tectonics- (1980-1989)