Mesozoic sedimentary rocks and depositional facies, Vizcaino-Cedros Area, Baja California, Mexico

Conference · Tue Apr 01 04:00:00 EST 1986 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:6987693

Boles, J R

Mesozoic sedimentary rocks in the Vizcaino-Cedros area constitute a 135-m.y. history of arc-related marine sedimentation with a cumulative thickness of 14 km. The Upper Triassic San Hipolito Formation is the oldest sedimentary unit in the region, and is recognized only on the Vizcaino Peninsula. The formation depositionally overlies an ophiolite sequence and consists of 2.4 km of tuffaceous sediment including a limestone megabreccia. The upper two-thirds of the sequence in the type section is now believed to be of Early Jurassic age. On Cedros Island, the basal sedimentary rocks are 1.2 km of the Lower Jurassic Gran Canon Formation. This richly tuffaceous unit depositionally overlies both ophiolite and arc volcanics. Conformably overlying the Gran Canon on Cedros Island is the Coloradito Formation, a spectacular sedimentary olistostrome up to 0.4 km thick, containing Triassic and late Paleozoic metasedimentary blocks. This formation record the first evidence of continental detritus in the region. Conformably overlying the Coloradito and, in part, stratigraphically equivalent to it on Cedros is 0.4 km of volcanogenic-metasedimentary conglomerate designated the Eugenia Formation. The Eugenia is much thicker (to 2.7 km) and widespread on Vizcaino where it unconformably overlies the San Hipolito Formation. On Vizcaino, the lower Eugenia (Upper Jurassic) includes spectacular volcanic debris flows interbedded with sandstone, but it is transitional upward into finer facies with increasing plutonic detritus. Time equivalent to the upper Eugenia and locally deposited on tonalite and volcanics is the Lower Cretaceous Asunction Formation (0.8 km thick). This sequence includes calcareous coarse breccias of serpentinized gabbros and tonalite.

• Research Organization: Univ. of California, Santa Barbara
• OSTI ID: 6987693
• Report Number(s): CONF-8604187-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 70:4
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
CARBONATE ROCKS
CONGLOMERATES
CRETACEOUS PERIOD
DEVELOPING COUNTRIES
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGY
JURASSIC PERIOD
LATIN AMERICA
LIMESTONE
MESOZOIC ERA
MEXICO
NORTH AMERICA
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
STRATIGRAPHY
TRIASSIC PERIOD