Early Cretaceous rifting and exposure of periodotite on the Galicia continental margin: preliminary results of ocean drilling program Leg 103

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:5892834

Winterer, E; Boillot, G; Meyer, A; Applegate, J; Baltuck, M; Bergen, J; Comas, M; Davies, T; Dunham, K; Evans, C; Girardeau, J

Results of drilling near the ocean-continent boundary on the Galicia margin of Iberia shed new light on the timing of rifting and demonstrate the presence at the foot of the margin of a ridge of foliated, lineated, sheared and serpentinized harzburgite, probably representing oceanic mantle. Fifty km east of the periodotite ridge, on a continental fault block, the stratigraphic section sampled during Leg 103 above Hercynian basement comprises: (1) at least 250m of Upper Jurassic and possibly lowest Cretaceous limestone, dolomite and minor sandstone and claystone deposited in relatively shallow water before rifting began; (2) about 20m of Valanginian calpionellid marlstone, probably deposited in moderate depths at the onset of rifting; (3) from about 500 to 1500m of Valanginian and Hauterivian turbidite sandstone rich in terrestrial plant debris, and Barremian and Aptian( ) claystone and marlstone deposited in deeper water during rifting; and (4) about 700m of sediments deposited after Aptian time, when rifting ceased and oceanic spreading between Iberia and Newfoundland began. The lithology and seismic stratigraphy of the wedges of clastic sediments laid down during rifting show the progressive filling of basins that formed by episodic listric faulting that began very early in the Cretaceous and continued for about 25 my. The Lower Cretaceous turbidite sandstone cored on the Galicia margin correlates with thick Lower Cretaceous turbidites cored off Morocco during DSDP Leg 50, and with Wealden deltaic and fluviatile deposits on both sides of the Atlantic.

• OSTI ID: 5892834
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580100 -- Geology & Hydrology-- (-1989)
580201* -- Geophysics-- Seismology & Tectonics-- (1980-1989)
BOREHOLES
CAVITIES
CONTINENTAL CRUST
CONTINENTAL MARGIN
CRETACEOUS PERIOD
DRILLING
EARTH CRUST
EARTH MANTLE
FEDERAL REGION VI
GEOLOGIC AGES
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOLOGY
GEOPHYSICAL SURVEYS
IGNEOUS ROCKS
LITHOLOGY
LOUISIANA
MESOZOIC ERA
NORTH AMERICA
OCEANIC CRUST
PERIDOTITES
PLATE TECTONICS
PLUTONIC ROCKS
RIFT ZONES
ROCKS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SEISMIC SURVEYS
STRATIGRAPHY
SURVEYS
TECTONICS
USA
WELL DRILLING