DEAN HENDRiCKSON 75

SOME NOTES ON THE LATE CENOZOIC DRAINAGE PATTERNS IN SOUTHEASTERN ARIZONA AND SOUTHWESTERN NEW MEXICO' By M. E. Cooley2 U. S. Geological Survey, Tucson, Arizona

INTRODUCTION rocks were involved in large-scale normal faulting and some compressional folding and thrusting (Sabins, The development of the drainage in southeastern 1957). Deposits of late Cenozoic age are not known Arizona and southwestern New Mexico has been con- to have been involved in the thrusting. Normal trolled and modified repeatedly by pulses of large-scale faulting, however, continued throughout late Cenozoic faulting, epeirogenic upwarping or subsidence, and time, but with decreased intensity; by the beginning volcanic activity. As a result—in late Cenozoic time, of time, faulting was minor. mainly during the Pliocene and Quaternary—a close The drainage and the main centers of deposition relation exists between these events and the evolution are difficult to reconstruct before late Cenozoic time, of the Gila and Salt Rivers, which are the two main owing to the difficulty in placing deposits of this age streams in the area. in their correct stratigraphic position. Some aid in Much has been written about the development of correlation is obtained from the association of these the Basin and Range physiographic province and its deposits with the volcanic rocks, which, during drainage patterns since the early geological surveys of Cenozoic time, show a rough transition in composition Gilbert (1875). These reports include studies by Lee from silicic to more mafic basalt types. The volcanic (1905), McKee (1951), Heindl (1958; 1962), Lance rocks extruded before late Cenozoic time are rhyolite, (1960), Melton (1960), Cooley and Davidson (1963), light-colored andesite, latite, dark andesite, andesitic Kottlowski and others (1965), and Cooley and others basalt, and dacite. During late Cenozoic time, (1967) that cover all or parts of the area. This report however, the volcanic rocks were mainly basalt. presents a working hypothesis of the drainage develop- Some indications of what the drainage may have ment based on regional trends in sediment size and been immediately preceding late Cenozoic time are the association of the sedimentary deposits with the shown in figure 1. In places, the drainage direction volcanic rocks and geologic structure, coupled with was similar to that of the present streams, but in other about 1,100 measurements of imbrication of pebbles places, such as in parts of the Santa Cruz and San and the direction of dip of the crossbeds. Pedro Valleys, the drainage direction was opposite to The author gratefully acknowledges Mr. J. D. Sell that of the present streams. for his aid in review of this report.

LATE CENOZOIC DRAINAGE INITIAL GEOLOGIC SETTING The main physiographic features and the ancestral Toward the end of middle Cenozoic time (mainly stages of the present drainage patterns were developed in the ), large-scale differential structural by late Cenozoic time, mainly in Pliocene and Quater- movements formed the mountain chains and valleys nary time. During the early part of late Cenozoic time, south of the Mogollon Rim. Pre-upper Cenozoic mainly in early to middle Pliocene time, the drainage sedimentary rocks, such as the Helmet Fanglomerate was imponded and probably produced more internally near Tucson (Cooper, 1960, p. 95), and the volcanic drained basins in southeastern Arizona and south- western New Mexico than during any other period (fig. 1). This was followed by a gradual integration of the internal drainage into through drainage and the establishment of the system (fig. 2). 1. Publication authorized by the Director, U.S. Geological Survey. Prepared in cooperation with the Arizona State Land Department. A large amount of alluvium was deposited in the 2. Geologist, US. Geological Survey, Water Resources Division, valleys throughout much of late Cenozoic time. Col- Tucson, Ariz. lectively, these deposits are more than 1,500 feet

EXPLANATION

Direction of sediment transport of older valley fill Am— Direction of sediment transport of deposits laid down immediately before late Cenozoic time pre- ceding the older valley fill

Approximate location of drainage divide

Approximate area of known fine- grained deposits of older valley fill

Fossil locality, early to middle Pliocene in a2e

Contact between alluvial valley and hard-rock mountain area

I r l I I Figure 1 -- Drainage during the deposition of the older valley fill, mainly in early and middle Pliocene time.

EXPLANATION

410 PAYSON 1 zl S PRINGERVIL 01)7c A I II Direction of sediment cr 2 transport of younger valley fill

Approximate location of drainage divide on nr% vAul 1211P Present area of internal drainage

SILVER I TV

Approximate area of known fine-grained deposits of younger valley fill

Fossil locality, Blancan (late Pliocene and early

446 Pleistocene) to early n._ in age so;q..11, post-Biancan mk- OUGL Contact between alluvial —1 0 20 40 MILES valley and hard-rock I I I I mountain area Figure 2 — Drainage during the deposition of the younger valley fill, mainly in late Pliocene and early Pleistocene time, and the present areas having internal drainage.

Arizona Geological Society — Guidebook III 77

thick in many large valleys, particularly the Phoenix Francisco River and been imp_andedin a basin_aur basin and Safford Valley. The alluvium is not a single the New Mexico-Arizona, State line. The water in sequence of deposits but chiefly represents two general Santa Cruz -valley apparently floWed into the southern periods of alluviation; in this report the deposits are part of the*Ichoenix basin, where it became imponded, referred to as the older valley fill and the younger and the je&n_pslro and Safford Valleys were large areas valley fill. Many investigators (Peterson, 1962, p. 41; of internal drainags, To the north, however, the Salt Gilluly, 1956, p. 118; Schwartz, 1953, p. 13-15) have River was throu h flowin as far downstream as the called the bulk of the late Cenozoic deposits the Gila Tonto jaasin,soushwestor_i_'ontalain,Atc_Augatal Conglomerate, or the Gila (?) Conglomerate (Gilbert, was imponde&near Phoenix and its main 1875), or the Gila (Heindl, 1963). In many tributary, the Verde River, had not vet become a places, however, the late Cenozoic deposits are referred through-flowing stream. to informally—the older alluvium and lake deposits in During the period of upwarping and downcutting the San Pedro and Sulphur Spring Valleys (Cooper preceding the deposition of the younger valley fill, and Silver, 1964, 'p. 94-95), deformed gravel and some drainages became integrated. uring the deposi- basin-fill deposits in the Safford Valley (Davidson, tion of the younger valley fill, the Salt Santa ,Cruz, 1961, p. C-151), and older and younger units of the Verde, and possibly the San Pedro Rivers drained into basin fill adjoining the Huachuca Mountains (Brown the phoenix basin, and perhaps -part Of the water and others, 1966, p. 15-18). continued westward across the basin (fig. 2). The Many exposures in southeastern Arizona and south- Gila River, however,wever , was still imponded in its upper western New Mexico show the contact between the . . reaches. Dun the YQ.P11.1T.LIA'M older and younger valley-fill deposits as a channeled fill the Gila(?)-San Francisciailivers.flowed into. the erosion surface; in places, the contact indicates an _Saff4s1 _Valley, as indicate4 by the rounded gravel of angular unconformity generally along basin margins. different lithologies in the upper part of the younger In one place in the San Pedro Valley, sediment of the valley fill east of Safford (E. S. Davidson, oral younger valley fill is deposited against a fault scarp commun., 1960). TheGilaRiyeLliowelsr,r_y_haya formed from the older valley fill (Montgomery, 1963). been impo • ed in pluvjaj jakellahc_504.thanzar.1421_ In the central part of many valleys, such as Sulphur the Duncan basin n 1 late in Pie • ene (R. B. Sprinkand Safford ValleysAnd the Duncan basin, that Morrison, oral commun., 1964). The Gila Riyer_in... probbly haLcontinusilaternal drainage during Jhe Safford V deposition of the younger valley fill, this unit overlies reaches oftherlyeralteLlpulmarggionaimpwarging conformably the older valley fill. that terminated of a youngeroun valley The older and younger valley-fill deposits consist of and established.thrslugh_clajograt_g_alli2og-B lan can mixtures of clay, silt, sand, and gravel. The gravel of timejiLthiLansi many other valleys in southeastern the younger valley fill usually contains more silt and Arizona and southwestern New Mexico. The upwarp- is more weakly cemented than the gravel of the older ing seems to be continuing at the present time, as valley fill. In most exposures, the younger valley fill evinced by the downward and headward cutting by has a reddish-brown hue, whereas the older valley fill streams, and only the Sulphur Spring Valley in Arizona is buff or gray. Fine-grained deposits, including some and a broad area near Lordsburg and Silver City, New gypsum in the Tonto basin (Lance and others, 1962, Mexico, are still internally drained (fig. 2). p. 98-99) and San Pedro Valley, are widely distributed in the older valley fill and are present in the center of As a result of the regional upwarping in the late most of the valleys (fig. 1). In the younger valley fill, part of Quaternary time, most streams removed large fine-grained deposits are not present everywhere, but amounts of alluvium and deepened the valleys. The there are large amounts of limestone in the Safford maximum amount of cutting probably was in the Valley (fig. 2). A few vertebrate fossils have been Safford Valley, where the valley was deepened by found in the valley-fill units. The fossils in the older about 900 feet. In the Santa Cruz Valley near Tucson valley fill are early to middle Pliocene in age, whereas and in much of San Pedro Valley, the valleys were the ones in the younger valley fill are late Pliocene to deepened by about 500 feet. Downcutting was slight early Quaternary and early post-Blancan in age (Lance, in the Phoenix basin, and some subsidence must have 1960, p. 156-157; Wood, 1960, p. 141). occurred, because post-younger valley-fill flood-plain During the early part of late Cenozoic time. when alluvium was deposited over a wide area to depths of the older valley fill was deposited and internal strainage_ 200 to 300 feet. The effects of the apparent sub- was prevalent, the Gila River system did not exist in sidence on the drainage was slight, and the Salt and its preseriTiorm (fig. 1). The water from pirT6TIFF- Gila Rivers and their main tributaries continued to be iiiiper-6177rainage mayiaieLlovved to the San — through-flowing streams. 78 Arizona Geological Society - Guidebook III

REFERENCES Kottlowski, F. E., Cooley, M. E., and Ruhe, R. V., 1965, Quaternary geology of the Southwest, in The Quaternary of the United States, Brown, S. G., Davidson, E. S., Kister, L. R., and Thomsen, B. W., 1966, H. E. Wright, Jr., and D. G. Frey, eds.: New Jersey, Princeton Univ. Water resources of Fort Huachuca Military Reservation, southeastern Press, p. 287-298. Arizona: U. S. Geol. Survey Water-Supply Paper 1819-D, 57 p. Lance, J. F., 1960, Stratigraphic and structural position of Cenozoic Cooley, M. E., and Davidson, E. S., 1963, The Mogollon Highlands-their fossil localities in Arizona: Arizona Geol. Soc. Digest, v.3, p.155-159. influence on Mesozoic and Cenozoic erosion and sedimentation: Lance, J. F., Downey, J. S., and Alford, Malcolm, 1962, Cenozoic Arizona Geol. Soc. Digest, v. 6, p. 7-35. sedimentary rocks of Tonto basin: New Mexico Geol. Soc. Field Cooley, M. E., and others, 1967, Arizona highway geologic map: Conf., 13th, 1962, Guidebook of the Mogollon Rim region, east- Arizona Geol. Soc. (In press.) central Arizona, p. 98-99. Cooper, J. R., 1960, Some geologic features of the Pima mining district, Lee, W. T., 1905, Underground waters of Salt River valley, Arizona: Pima County, Arizona: U. S. Geol. Survey Bull. 1112-C, p.63-103. U. S. Geol. Survey Water-Supply Paper 136, 196 p. Cooper, J. R., and Silver, L. T., 1964, Geology and ore deposits of the McKee, E. D., 1951, Sedimentary basins of Arizona and adjoining areas: Dragoon quadrangle, Cochise County, Arizona: U. S. Geol. Survey Geol. Soc. America Bull., v. 62, p. 481-506. Prof. Paper 416, 196 p. Melton, M. A., 1960, Origin of the drainage of southeastern Arizona: Davidson, E. S., 1961, Fades distribution and hydrology of inter- Arizona GeoL Soc. Digest, V. 3, P. 113-122. montane basin fill, Safford basin, Arizona, in Geological Survey research 1961: U. S. Geol. Survey Prof. Paper 424-C, p. 151-153. Montgomery, E. L., 1963, The geology and ground water investigation Gilbert, G. K., 1875, Report on the geology of portions of Nevada, of the Tres Alamos Dam Site of the San Pedro River, Cochise Utah, California, and Arizona: U. S. Geog. and Geol. Surveys W. County, Arizona: Arizona Univ., Tucson, unpublished master's 100th Meridian, v. 3, p. 17-187. thesis, 69 p. Gilluly, James, 1956, General geology of central Cochise County, Peterson, N. P., 1962, Geology and ore deposits of the Globe-Miami Arizona: U. S. GeoL Survey Prof. Paper 281, 169 p. district, Arizona: U. S. Geol. Survey Prof. Paper 342, 151 p. Heindl, L. A., 1958, Cenozoic alluvial deposits of the upper Gila River Sabins, F. F., Jr., 1957, Geology of the Cochise Head and western part area, New Mexico and Arizona: Arizona Univ., Tucson, unpublished of the Vanar quadrangles, Arizona: Geol. Soc. America Bull., v. 68, doctoral thesis, 249 p. no. 10, p. 1315-1341. -1962, Cenozoic geology of Arizona-a 1960 resume: Arizona Schwartz, G. M., 1953, Geology of the San Manuel copper deposit, Geol.'Soc. Digest, v. 5, p. 9-24. Arizona: U. S. Geol. Survey Prof. Paper 256, 65 p. 1963, Cenozoic geology in the Mammoth area, Pinal County, Wood, P. A., 1960, Paleontological investigations in the 111 Ranch Arizona: U.S. Geol. Survey Bull. 1141-E, 41 p. area: Arizona Geol. Soc. Digest, v. 3, p. 141-143.