Lithofacies of deep marine basalts emplaced on a Jurassic backarc apron, Baja California (Mexico)

Journal Article · Tue Sep 01 00:00:00 EDT 1987 · J. Geol.; (United States)

DOI:https://doi.org/10.1086/629163· OSTI ID:5515980

Busby-Spera, C J

Basalts of the mid-Jurassic Gran Canon Formation, Cedros Island, Mexico, were emplaced on a volcaniclastic apron in a deep marine backarc basin. Elongate pillows and lava tubes, as well as paleocurrent data from the volcaniclastic apron, indicate a southward regional paleoslope away from the island arc source. Basalts emplaced on relatively proximal parts of the apron are nearly entirely pillowed and have thick flow units with mega-pillows. Basalts on distal parts of the apron (about 15 to 20 km down paleo-current) are dominated by pillow fragment breccias (flow foot rubble), and individual lava flows are generally thin, with small pillows, suggesting that the distal ends of lava flows, erupted upslope, are represented. These distal flow fronts, however, are interstratified with features that typically form close to a vent, including thick massive to mega-pillowed lavas and lava tubes up to 8 m in diameter. It is inferred that a fissure (or system of fissures) extended from the arc into the backarc basin, erupting basalt lavas onto both proximal and distal parts of the volcaniclastic apron. Such intraplate volcanism may be common on the hot frontal arc side of backarc basins. 26 references.

• Research Organization: Univ. of California, Santa Barbara
• OSTI ID: 5515980
• Journal Information: J. Geol.; (United States), Vol. 95:5
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
MEXICO
VOLCANIC REGIONS
GEOLOGIC HISTORY
BASALT
FLUID FLOW
GEOLOGIC FISSURES
JURASSIC PERIOD
LAVA
MORPHOLOGY
OFFSHORE SITES
UNDERWATER
VOLCANISM
DEVELOPING COUNTRIES
GEOLOGIC AGES
GEOLOGIC STRUCTURES
IGNEOUS ROCKS
LATIN AMERICA
LEVELS
MESOZOIC ERA
NORTH AMERICA
ROCKS
VOLCANIC ROCKS
580202* - Geophysics- Volcanology- (1980-1989)