U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY BRECCIA-PIPE AND GEOLOGIC MAP OF THE SOUTHEASTERN PART OF THE HUALAPAI INDIAN RESERVATION AND VICINITY, ARIZONA By George H. Billingsley, Karen J. Wenrich, and Peter W. Huntoon 2000 Prepared in cooperation with the U.S. BUREAU OF INDIAN AFFAIRS AND THE HUALAPAI TRIBE Pamphlet to accompany GEOLOGIC INVESTIGATIONS SERIES I-2643 (I Printed on recycled paper CONTENTS Introduction ............................................................................................. , . 1 Geologic setting ........................................................................................ ;. .. .. .. .. .. .. .. .. .. .. .. 1 Structural geology ................................................................................... , . 3 Tectonic overview .............................................................................. , . 3 Cenozoic uplift and erosion .................................................................. ·..................................... 4 Deformation of the Paleozoic section .......................................· ............ ~.................................... 4 Laramide monoclines .......................................................................... , ................ ;. 5 Late Cenozoic faulting and extension . .. 5 Paleogeographic reconstructions ........................................................ , . 7 Breccia pipes . •. 8 Introduction ....................................................................................... , . 8 Structural control of breccia pipes .......................................................•..................................... 9 The Blue Mountain Pipe ...................................................................... , . 11 Collapse features having economic potential ......................................... •·.................................. 11 Conglomerate cave ............................................................................ , . 12 Conclusions ........................................................................................................................... 12 Acknowledgments ..................................................................................... , . 12 Description of map units ........................................................................... ~................................... 13 References cited . 1 7 FIGURES 1. Geographic map of the southeastern part of the Hualapai Indian Reserva~ion, Arizona ................ 2 2. Diagrammatic cross sections showing the stages in the development of the Hurricane ............... 6 Fault Zone in the western Grand Canyon. 3. Map of breccia pipes and springs in the Blue Mountain/Diamond Creek ar¢a .............................. 10 INTRODUCTION This report includes two maps, map A showing geology and breccia pipes coded into The map area encompasses about 660 mi2 categories, and map B showing only the breccia (1,050 km2) of the southeastern part of the pipes and their respective pipe number and Hualapai Indian Reservation, a part of Grand category. Breccia and collapse structures in the Canyon National Park (northwest edge of map extreme northwest corner of the map area are area), and private and State lands that border those mapped by Huntoon and others (1981). the southeastern and eastern boundaries of the All pipes in the mineralized category were sam­ Reservation (fig. 1). The map area is in that part pled; petrographic, mineralogic, and geochemical of the southwestern Colorado Plateaus physio­ studies are in progress. Initial mapping of the graphic province that is dissected by the Col­ pipes and sinkholes was done using 1976, orado River to form the Grand Canyon and its 1:24,000-scale color aerial photographs. Each system of tributary canyons. collapse feature was visited and examined by he­ Hundreds of solution-collapse breccia pipes licopter or vehicle. Radiometric traverses were are found in the Hualapai Indian Reservation and made across all but a few of the pipes and sink­ adjacent areas in northwestern Arizona. Many holes. Collapse features not field checked are in pipes contain uranium and copper minerals and the Redwall Limestone and were determined to anomalous concentrations of Ag, Co, Mo, Ni, have little economic potential based on previous Pb, and Zn. In the map area, 231 confirmed and field investigations (Billingsley and others, 1986; suspected breccia pipes and collapse features Wenrich and others, 1996, 1997). have been recognized. Of these, approximately 8 percent have copper or other minerals, or GEOLOGIC SETTING have gamma radiation in excess of 2.5 times background level. The oldest rocks in the map area are Early This research was funded by the Bureau of Proterozoic granites, schists, and gneisses ex­ Indian Affairs in cooperation with the Hualapai posed along the Colorado River and in the Dia­ Tribe to appraise the mineral potential of the mond Creek drainages (northwestern part of Hualapai lands. The entire 1,550 mi2 (2,465 map area). The metamorphic rocks are mostly k m 2) Hualapai Reservation has been mapped in the middle and upper amphibolite facies. Early geologically at a scale of 1:48,000 (Wenrich and Proterozoic pegmatite and diabase dikes intrude others, 1996, 1997; Billingsley and others, these rocks throughout the area (Huntoon and 1999). Within the Reservation, all breccia pipes others, 1981). and collapse features have been plotted. Outside Exposed in canyon walls and on the the Reservation, several pipes are shown by plateaus are Paleozoic strata ranging in age from symbols based on the work of Huntoon and Cambrian to Permian. The youngest exposed others (1981) and this project. A few well­ Paleozoic unit is the resistant Kaibab Formation defined collapse features outside of the of Early Permian age, which forms the surface of Reservation are shown. the Coconino Plateau. Rocks of Pennsylvanian The top of the Aubrey Cliffs forms the and Mississippian age crop out locally in Aubrey boundary between the Coconino Plateau in the Valley and in the southwestern part of the map northern and northeastern parts of the map area, although at many places they are covered area and the Aubrey Valley in the southwestern by Cenozoic deposits. Strata of Ordovician and part of the map area (fig. 1). The Aubrey Valley, Silurian age are not present in the region or map a broad alluviated plain that conceals any under­ area. Their position in the section is marked by lying breccia pipes, is bounded on the west by a regional disconformity that separates rocks of tributary canyons to Peach Springs and Dia­ Cambrian and Devonian age. mond Creek Canyons. The Hualapai Plateau is Deposits of Late Cretaceous to Holocene west of Aubrey Valley and is a broad, irregular­ age are locally present. The Cenozoic deposits shaped plateau of low relief that breaks off into cover much of the Paleozoic rocks on the canyons along the Hurricane Fault. The Grand plateaus, the large upland valleys, and in Aubrey Canyon and its tributaries are in the western Valley. In the tributary canyons of the Col­ and northwestern parts of the map area. Eleva­ orado River, Cenozoic rocks are mostly limited tions range from 1,340 ft (408 m) above sea to younger landslides, travertine, and talus de­ level at the Colorado River to 7,392 ft (2,253 m) posits. at Manzanita (benchmark) on the Aubrey Cliffs The oldest Cenozoic rocks consist of two north of Diamond Creek, giving a maximum relief units: a consolidated gravel and conglomerate of 6,052 ft (1,845 m) in the map area. unit that fills a 2-mi (3.2 km) wide paleovalley 1 AREA OF AREA OF 1-2440 1-2522 MAP AREA UNMAPPED 113°22'30" 35°52'30" fHualapai Hilltop 30mi Peach Springs 3.5mi \ 10 MILES I I I 10 15 KILOMETERS Agure 1. Geographic map of the southeastern part of the Hualapai Indian Reservation, Arizona. 2 east of and between upper Diamond Creek and Sediments of similar lithology occur throughout Blue Mountain (central part of map area), and a the Hualapai and Coconino Plateaus and have consolidated gravel and fanglomerate unit that been shown to be no younger than middle fills a paleovalley and adjacent erosional scarp Miocene (Young, 1999). In summary, the Blue just north of Blue Mountain. Both deposits Mountain gravel and Frazier Well gravel of consist of Paleozoic clastic material in a gravelly Koons (1948a, b) and part of the Hindu Canyon sandstone matrix described informally and to­ Formation of Gray (1959, 1964) are all equated gether as the Robbers Roost gravel by Koons with the Music Mountain conglomerate of (1948a, b, 1964). The deposits are considered Young (1966) just east of this map, which is to be Late Cretaceous to late Paleocene in age formally proposed as the Music Mountain For­ because their stratigraphic position is about mation (Young, 1999). equivalent to that of similar Paleozoic clastic Modern erosion of the Robbers Roost gravel deposits below Eocene lacustrine deposits gravel, the Frazier Well gravel, and local Paleo­ a few miles east of the map area on the Co­ zoic outcrops have resulted in an extensive conino Plateau (Young, 1985, 1999). The cover of younger undifferentiated gravel deposits Robbers Roost gravel in the higher paleovalley (T g). These deposits consists of unconsolidated on a ridge east of upper Diamond Creek con­ to partly consolidated mixed lithologies of Pro­ tains conglomerate clasts from the Coconino terozoic and Paleozoic clastic material. These Sandstone, the Toroweap Formation, and the Tertiary deposits are middle Miocene to Pliocene