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An Alluvial Surface Chronology Based on Cosmogenic36Cl Dating, Ajo Mountains (Organ Pipe Cactus National Monument), Southern Arizona

Published online by Cambridge University Press:  20 January 2017

Beiling Liu ,
Fred M. Phillips ,
Molly M. Pohl  and
Pankaj Sharma
Beiling Liu
Affiliation:
Department of Geoscience, New Mexico Tech, Socorro, New Mexico, 87801
Fred M. Phillips
Affiliation:
Department of Geoscience, New Mexico Tech, Socorro, New Mexico, 87801
Molly M. Pohl
Affiliation:
Department of Geography, Arizona State University, Tempe, Arizona, 85287
Pankaj Sharma
Affiliation:
PRIME Lab. Physics Department, Purdue University, West Lafayette, Indiana, 47907
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Abstract

A chronology of alluvial surfaces on piedmont slopes below the western Ajo Mountains, southern Arizona, has been obtained using cosmogenic 36Cl accumulation and AMS radiocarbon dating. The apparent 36Cl ages of individual boulders range from 520,000 to 13,000 yr, and the 14C ages of organic material in the two young terraces are 2750–2350 and 17,800 cal yr B.P. The sequence of36Cl ages is consistent with the apparent stratigraphic order, but groupings of similar ages for different surfaces appear to result from repeated reworking of older surfaces associated with the deposition of younger ones. The youngest surface gave a distribution of 36Cl ages about 30,000 yr older than the 14C and soil ages; however, this distribution had36Cl ages that overlapped with 36Cl ages from active channels and hillslopes. We attribute the older-than-expected exposure ages of sampled boulders to inheritance of 36Cl while residing near the surface during very slow erosion on the mountain front. Our results show that although cosmogenic nuclide accumulation can help establish chronologies for surfaces in piedmont settings, care must be used in evaluating the effects of complex exposure histories.

Type
Research Article
Information
Quaternary Research , Volume 45 , Issue 1 , January 1996 , pp. 30 - 37
Copyright
University of Washington

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References

Birkeland, P. W. (1984). “Soils and Geomorphology.” Oxford Univ. Press, New York.Google Scholar
Bryan, K. (1922). Erosion and sedimentation in the Papago Country, Arizona, with a sketch of the geology. U.S. Geological Survey Bulletin 730 , 19–90. Denny, C. S. (1967). Fans and pediments. American Journal of Science 265 , 81–105.Google Scholar
Dohrenwend, J. C. (1987). Basin and Range. In “Geomorphic Systems of North America, Centennial Special Volume 2” (William, G. L., Ed.), pp. 303–342. Geological Society of America, Boulder, LO.Google Scholar
Dorn, R. I. Jull, A. J. T. Donahue, D. J. Linick, T. W., and Toolin, L. J. (1989). Accelerator mass spectrometry radiocarbon dating of rock varnish. Geological Society of America Bulletin 101 , 1363–1372.Google Scholar
Fabryka-Martin, J. (1988). “Production of Radionuclides in the Earth and Their Hydrologic Significant, With Emphasis on Chlorine-36 and Iodine-129.” Unpublished Ph.D. dissertation, The University of Arizona, Tucson.Google Scholar
Gile, L. H. Peterson, F. F., and Grossman, R. B. (1966). Morphological and genetic sequences of carbonate accumulation in desert soils. Soil Science 101 , 347–360.Google Scholar
Gile, L. H. Hawley, J. W., and Grossman, R. B (1981). “Soils and Geomorphology in the Basin and Range Area of Southern New Mexico—Guidebook to the Desert Project.” Memoir 39 , New Mexico Bureau of Mines and Mineral Resources, Socorro.Google Scholar
Harden, J. W. Mark, R. M., and Switzer, P. (1988). Soil development as a correlation and dating tool; concepts, quantitative methods, and limitations. Abstracts with Programs 3(20), 166.Google Scholar
Jenny, H. (1941). “Factors of Soil Formation.” McGraw-Hill, New York.Google Scholar
Jull, A. J. T. Donahue, D. J., and Linick, T. W. (1989). Spallogenic C-14 in high-altitude rocks and in Antarctic meteorites. Radiocarbon 31 , 719–724.Google Scholar
Klein, J. Giegengack, R. Middleton, R. Sharma, P. Underwood, R. J. Jr., and Weeks, R. A. (1986). Revealing histories of exposure using in situ produced Al-26 and Be-10 in Libyan Desert Glass. Radiocarbon 28 , 547–555.Google Scholar
Kurz, M. D. (1986). In situ production of terrestrial cosmogenic helium and some applications to geochronology. Geochimica et Cosmochimica Acta 50 , 2855–2862.Google Scholar
Liu, B. (1994). “Cosmogenic 36Cl Dating of Geomorphic Surfaces and Isotopic Investigation of Soil Water and Paleoclimate, Ajo Mountains, Southern Arizona.” Unpublished Ph.D. dissertation, New Mexico Institute of Mining and Technology, Socorro.Google Scholar
Liu, B. Phillips, F. M. Fabryka-Martin, J. T. Fowler, M. M. Biddle, R. S., and Stone, W. D. (1994a). Cosmogenic 36Cl accumulation in unstable landforms, I. Effects of the thermal neutron distribution. Water Resources Research 30 , 3115–3125.Google Scholar
Liu, B. Phillips, F. M. Elmore, D., and Sharma, P. (1994b). Depth dependence of soil carbonate accumulation based on cosmogenic 36Cl dating. Geology 22 , 1071–1074.Google Scholar
Morrison, R. B. (1991). Quaternary geology of the southern Basin and Range province. In “Quaternary Nonglacial Geology: Conterminous U.S.” (Morrison, R. B., Ed.), pp. 353–371. Geological Society of America, Boulder, LO.Google Scholar
Phillips, F. M. Leavy, B. D. Jannik, N. O. Elmore, D., and Kubik, P. W. (1986). The accumulation of cosmogenic chlorine-36 in rocks: A method for surface exposure dating. Science 231 , 41–43.Google Scholar
Phillips, F. M. Zreda, M. G. Elmore, D., and Sharma, P. (1995). Reevaluation of cosmogenic 36Cl production in terrestrial rocks. Submitted.Google Scholar
Pohl, M. (in press). First radiocarbon ages on organics from piedmont alluvium, Ajo Mountain, Arizona. Physical Geography. Google Scholar
Ritter, D. F. (1978). “Process Geomorphology.” Brown, Dubuque, IA.Google Scholar
Shafiqullah, M. Damon, P. E. Lynch, D. J. Reynolds, S. J. Rehrig, W. A., and Raymond, R. H. (1980). K-Ar geochronology and geologic history of southwestern Arizona and adjacent area. In “Studies in Western Arizona” (Jenney, J. P. and Stone, C., Eds.), Arizona Geological Society Digest 12 , pp. 201–260. Tucson, AZ.Google Scholar
Simpson, D. T. (1991). “Soil and Geomorphology of the Quaternary Alluvial Sequences on the Western Piedmont of the Ajo Mountains, Organ Pipe Cactus National Monument, Pima County, Arizona.” Unpublished M.S. thesis, University of New Mexico, Albuquerque.Google Scholar
Swanson, T. W. (1994). Application of 36Cl dating based on the deglaciation history of the Cordilleran ice sheet in Washington and British Columbia. Abstracts with Programs 26(7), 512.Google Scholar
Zreda, M. G. (1994). “Development and Calibration of Cosmogenic 36Cl Method and Application to Chronology of Late Quaternary Glaciations.” Unpublished Ph.D. dissertation, New Mexico Institute of Mining and Technology, Socorro.Google Scholar
Zreda, M. G. Phillips, F. M. Elmore, D. Kubik, R. W., and Sharma, P. (1991). Cosmogenic chlorine-36 production rates in terrestrial rocks. Earth and Planetary Science Letters 105 , 94–109.Google Scholar