Mass-gravity deposits and structures in the Lower Cretaceous of Sonora, Mexico

Abstract

Research Article| December 01, 1998 Mass-gravity deposits and structures in the Lower Cretaceous of Sonora, Mexico Mary Beth McKee; Mary Beth McKee 17118 Clow Road, Winneconne, Wisconsin 54986 Search for other works by this author on: GSW Google Scholar Thomas H. Anderson Thomas H. Anderson 2University of Pittsburgh, Department of Geology and Planetary Science, 321 Old Engineering Hall, Pittsburgh, Pennsylvania 15260 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1998) 110 (12): 1516–1529. https://doi.org/10.1130/0016-7606(1998)110<1516:MGDASI>2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Mary Beth McKee, Thomas H. Anderson; Mass-gravity deposits and structures in the Lower Cretaceous of Sonora, Mexico. GSA Bulletin 1998;; 110 (12): 1516–1529. doi: https://doi.org/10.1130/0016-7606(1998)110<1516:MGDASI>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Rocks that form the south flank of Sierra Azul, northern Sonora, Mexico, are correlative with the Jurassic(?) and Lower Cretaceous Bisbee Group of southern Arizona. We interpret them as basinal marine deposits featuring both mass-gravity deposition and deformation. Thick (hundreds of meters) bodies of sediment showing some internal disaggregation are separated by slide surfaces that cut down-section into footwalls. We believe that further mass movement formed these stacked slide masses into northwest-trending, southwest-vergent folds, though they contain many features normally associated with direct tectonism. Thus, the folds are not the product of Laramide crustal shortening, but rather they reflect earlier (Jurassic and Cretaceous) high-angle crustal movement that produced the paleo-upland (the Cananea high), the basin, and the slope that guided their development. We suggest their vergence shows paleoslope, not tectonic transport.This basinal marine sequence contains blocks of reefal limestone equivalent to the upper Mural Limestone (Bisbee Group) that have been widely used as evidence of an in situ carbonate bank; here, they are allochthonous. We suggest that they may have been derived from the margin waters of the Cananea high. Confusion of structures such as these formed by mass-gravity processes may be one reason that the pattern of Laramide deformation in northern Sonora is still poorly defined. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not currently have access to this article.