Arizona Geological Society

Transcription

1 Arina Gelgical Sciety Field Trip t Clssal Cave and the Surrunding Area, Pima Cunty, Arina Leader: William Peachey, Spelelgist Clssal Cave Muntain Park February 19, 2000 Clssal Cave Muntain Park

2 Clssal Cave Muntain Park Physical and Bilgical Resurces General Gelgy Intrductin: Clssal Cave Muntain Park is the nly interpretive site in the Pima Cunty parks system here visitrs can vie, in_ clse prximity t ne anther, rk units representing the entire span f gelgic time in suthern Arina as ell as evidence f the physical changes that accmpanied gelgic events. Faults and flds are represented at all scales. Evidence f the expansin and shrinkage f rck vlumes is fund thrughut the study area. Evidence f metamrphic changes in rcks-i. e., quartite frm sandstne, marble _ frm limestne, and gneiss frm granite-is equally cmmn. Mre subtle assciatins frmed by faulting reveal relative mvements f large vlumes f rck n the rder f tens f miles hrintally and thusands f feet vertically ver tens f millins f years. The cave and canyn terrain als alls direct bservatin f the effects f physical and chemical ersin and depsitin, bth as the result f past events and as dynamic frces still shaping the Snran desert. What e see tday is a msaic f rck types and ages in very cmplex relatinships ith ne anther as they frm a prtin f the suthestern flank f the Rincn Muntains ithin the Basin and Range physigraphic prvince. This prvince is characteried by islated muntain rck masses hse intervening valley flrs hlve settled bel them. Typically, the valleys cntain thusands f feet f sediments erded frm the muntains that brder them. The initial published gelgic investigatin in the area, f hich e are aare, as cnducted by Dartn in In it, he ntes the curius psitin f Paleic limestnes that appeared t have been thrust ver Precambrian granite. Over the intervening decades the true character f that relatinship remained unknn.

3 Actually preceeding Dartn, the first" frmal mapping effrt at Clssal Cave tk place in This as undertaken by Byrn Cummings, the first head f the Anthrplgy Department at the University f Arina. Cummings had assistants in the surveying, ne f hm as Lynn Hdgsn, then a lcal teenager, h as t becme a prminent suthern Arina utdrsman. Hdgsn died at age 96 in 1996, evidently the last f the riginai gelgical investigatrs f the Celssal Cave area. Unfrtunately, neither the map nr a reprt n the effrt as published, and any cpies f the map have since disappeared. Tday the nly existing recrd f the map cnsists f an incmplete set f data reductin tables f the surveys. Since the early rk by Cummings and Dartn, many studies, bth published and unpublished, have addressed questins abut the Clssal Cave Muntain Park area. These are t numerus t detail here and s have been cmpiled as part f the bibligraphy t this reprt. These references supprt current vies f estern reginal Nrth American gelgy: that is, three significant eyents, hich ccurred relatively late in gelgic time, are largely respnsible fr the landscapes e see in the regin tday. They are the Laramide rgeny, a muntain-building episde that ccurred millin years ag (m. y. a.), the Mid-Tertiary extensin,30-20m. y. a., and the Basin and Range extensin, 15-5 m. y. a. These events verprinted the vast number f the lder rck units in the area (that is, they masked lder chemical and physical characteristics ith yunger. nes), and even verprinted the rck units prduced by ne anther, t yield the great cmplexity and diversity e see tday in the gelgy f Clssal Cave Muntain Park and the study area.

4 QUAT COLOSSAL CAVE MOUNTAIN PARK PLIOCENE MIOCENE t= a::: OLIGOCENE t- EOCENE PALEOCENE GEOLOGIC UNITS* ALLUVIUM M M SIL. RED BRECCIA PANTANO FORMATION TURKEY TRK. ANDESITE WRONG MOUNTAIN NIPPER FORMATION 24 M.Y. RADIOMETRIC AGE-DATE c::: N...J Cl.. M rn :J 0 t- a::: 0 LATE UPPER VOLCANIC SEQUENCE FORT CRITTENDEN FORMATION CINTURA FORMATION EARLY BISBEE GROUP MURAL LIMESTONE WILLOW CANYON FM.-M GLANCE CONGLOMERATE 'OCHOAN RAlNVALLEY FORMATION GUADALUPIAN CONCHA LIMESTONE SCHERRER FORMATION a::: LEONARDIAN LLJ EPITAPH FORMATION l.. COLINA LIMESTONE WOLFCAMPIAN EARP FORMATION VlRGILlAN MISSOURIAN LLJ DES MOINESIAN HORQUILLA LIMESTONE l.. ATOKAN MORROWAN "...,.,...,..., ,......,...,......, CHESTERIAN PARADISE FORMATION en rn MERAMECIAN OSAGIAN ESCABROSA LIMESTONE (COLOSSAL CAVE) KINDERHOOKIAN OZ > _ LATE MARTIN LIMESTONE Cl!!:ci EARLY EL PASO LIMESTONE LATE = _ FRANCONIAN = a: c :E MIDDLE EARLY ABRIGO FORMATION,/f BOlSA QUARTZITE LATE PIONEER SHALE M a: c RINCON VALLEY GRANODIORITE :E MIDDLE!!: EARLY 01.SB.Y. RADIOMETRIC AGE-DATE - FOUND WITHIN COLOSSAL CAVE MOUNTAIN PARK M - ILLUSTRATED ON STUDY AREA-GEOLOGY MAP * - AFTER BRYANT 1968, DREWES 1977, KRANTZ 1983, DICKINSON RICHARD & HARRIS 1996.

5 Clssal Cave N Partial Plan Vie The Cave Ttals 12,000+ f Passage E-3 E-l Tur Entrance E-2 Cvered EntrBDce(per) E-3 Guan Mining Tunnel( 1905) E-4 "Bandits Escape" Entrance E-5 C.C.c. Cnstr. Shaft E-4 M Match line f Maps- Brd(1987)/UAAC Grtt(1965) This map is the same as Plate 3, reduced t a scale f apprximately 11 meters per cm., and is included t sh the verall pattern f the cave I Brd, L.G. Gelgy and Spelegenesis f Clssal Cave, Pima Cunty, i Arina. Unpub. M.S., Univ. A., 1987.