Sedimentation and volcanism in the Hopi Buttes, Arizona

Research Article| February 01, 1942 Sedimentation and volcanism in the Hopi Buttes, Arizona JOHN T. HACK JOHN T. HACK Search for other works by this author on: GSW Google Scholar GSA Bulletin (1942) 53 (2): 335–372. https://doi.org/10.1130/GSAB-53-335 Article history received: 12 Jun 1941 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation JOHN T. HACK; Sedimentation and volcanism in the Hopi Buttes, Arizona. GSA Bulletin 1942;; 53 (2): 335–372. doi: https://doi.org/10.1130/GSAB-53-335 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The Hopi Buttes area in the southern Navajo Country, Arizona, lies in a Pliocene basin of sedimentation and volcanism. The thin Pliocene sediments, known as the Bidahochi formation, are interbedded calcareous sand, clay, marl, tuff and other pyroclastic material. These sediments extend southeastward as far as the Zuni area, New Mexico. They overlie the Hopi Buttes erosion surface of low relief, a portion of which is now exhumed on the southern edge of Black Mesa. This surface may be widespread in northern Arizona. The Bidahochi formation and the erosion surface have evidently been deformed in Pliocene or post-Pliocene time.The Hopi Buttes area, which lies at the lowest point of the structural basin of deformation, contains Pliocene volcanic rocks of alkalic composition greater in volume than the sediments, and over 200 closely spaced volcanic necks or diatremes ranging from 500 to 4000 feet in diameter, and arranged along a complex pattern of fractures.Flows are few in number, for the volcanism produced pyroclastic débris and lava domes. Deep erosion reveals that explosions produced funnel-shaped pipes which were rapidly filled with explosion débris, with material poured in by streams or with lava and viscous agglomerate erupted from below. Small rims protected many diatremes for a time from filling by river-borne sediments so that fine ash, gypsum, and calcium carbonate collected in their crater lakes to be later buried by coarser material as stream aggradation continued. The structure of the diatreme fillings indicates that subsidence occurred after eruption. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.