Late Paleozoic volcanic arc in southern Coahuila, Mexico: further definition
About 4000 m of Late Pennsylvanian and Permian rocks exposed NW of Las Delicias (now Nueva Delicias) are all marine sediments deposited below storm wave base. Principal components are andesitic and dacitic volcanic debris, pelagic siliciclastic sediment, and limestone debris. Virtually all of the sediment was transported by mass-gravity processes. Volcanic debris ranges in size from silt and sand of turbidites to great blocks of basin-margin and extra-basinal volcanic rocks which form a more-or-less intact slide mass up to 300 m thick and over 10km in exposed length. Limestone debris was derived from the shallow-water margin of the basin; clasts range in size from sand to blocks a few tens of meters across. Debris was transported by both sediment gravity flow and sliding; post-depositional transportation of pelagic sediment was principally by sliding. Strata accumulated in an arc-proximal basin which persisted through the Permian. Beds record macroscopic, syndepositional folds and faults mainly generated by downslope movement. Stratigraphic evidence and soft-sediment structures indicate sediment derivation from the south or east; the authors interpret the volcanic rocks at Canon Rosillo as a portion of the arc from which the sediments were derived. On petrographic evidence, the volcanic rocks are calc-alkaline; because of this and the rare occurrence of granite boulders in debris flows low in the section, they suggest that the arc may have developed on crust with continental affinities. Mesozoic, pre-Cretaceous deformation has compressed the Paleozoic beds into a folded syncline.
- Research Organization:
- Univ. of Wisconsin, Oshkosh (USA)
- OSTI ID:
- 6459963
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Vol. 17; ISSN GAAPB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580300* -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
DEPOSITION
DEVELOPING COUNTRIES
EROSION
GEOLOGIC AGES
GEOLOGIC HISTORY
GEOLOGY
IGNEOUS ROCKS
LATIN AMERICA
MEXICO
NORTH AMERICA
PALEOZOIC ERA
PENNSYLVANIAN PERIOD
PERMIAN PERIOD
PETROGENESIS
PETROGRAPHY
PETROLOGY
ROCKS
SEDIMENTARY ROCKS
SEDIMENTS
STRATIGRAPHY
VOLCANIC REGIONS
VOLCANIC ROCKS
VOLCANISM