K. H. McKKE Age and Rate of Movement of the Northern Part of the Death Valley-Furnace Creek Fault Zone, California Abstract: Large right -lateral displacements along the Death Valley-Furnace Creek fault zone have probably taken place since Middle Jurassic time. Matching of Middle Jurassic granitic rocks (160 m.y. old by K-Ar dating) on either side of the fault zone suggests displacement on the order of 30 miles. The distribution of Pliocene sedimentary rocks (3.5 m.y. old by K-Ar dating) in the same region suggests the possibility of approximately 3000 feet of right-lateral movement since Pliocene time. The calculated rate of displacement since the Middle Jurassic is similar to the , . _,. 30 miles 3.5 miles tentative rate since the late Pliocene: — ^ 160 m.v. 0.6 m.y. Introduction Jurassic granitic rocks. The Sylvania Moun- tains bordering the north side of the Death The Death Valley-Furnace Creek fault zone Valley-Furnace Creek fault zone at the south is an important structural feature in the Death end of Fish Lake Valley are composed mostly Valley region of eastern California. Movement of medium- to coarse-grained granitic rocks. along the fault zone is generally considered to One of the main rock types is a distinctive por- be strike-slip with right-lateral displacement phyritic quartz monzonite which crops out over (Lock and others, 1940; Noble and Wright, an area of approximately 100 square miles. A 1954; Drewes, 1963; Stewart, 1967). Estimates K-Ar date on biotite from this rock gave an age of the amount of right-lateral displacement of 155 ± 3 m.y. (Table 1, no. 1; McKee, Ph.D. along the zone differ widely. A limit of several thesis, University of California at Berkeley, miles of total right-lateral displacement has 1962), which is Middle Jurassic. Approximately been suggested by Wright and Troxel (1967), 8 miles northwest of the Sylvania Mountains while Drewes (1963, p. 56) proposed displace- on the south side of Fish Lake Valley granitic ment of 15 to 30 miles and Stewart (1967), sug- rocks crop out, which are part of the Inyo gested movement of as much as 50 miles. batholith (Fig. 2A). One of the most distinctive The Fault Zone rocks in this part of the batholith resembles the porphyritic quartz monzonite of the Sylvania The northern portion of the Death Valley- Mountains. The age determined by the K-Ar Furnace Creek fault zone is well exposed from method on biotite from this porphyritic quartz the north end of Death Valley northwest to monzonite is 161 + 4 m.y. (Table 1, no. 2; Fish Lake Valley where the fault is buried by McKee, Ph.D. thesis, University of California Quaternary alluvium (Fig. 1). Along the north- at Berkeley, 1962). eastern edge ol the Last Chance Range and the The similarity in lithology and age between southwestern edge of the Sylvania Mountains, the porphyritic quartz monzonite of the Sylva- the fault zone is about half a mile wide and nia Mountains on the north side of the Death brings Jurassic granitic rocks on the east against Valley-Furnace Creek fault zone and the por- Precambrian and Cambrian sedimentary rocks phyritic quartz monzonite on the south side on the west. The fault zone in the south end of of the fault zone suggests that they are parts of Fish Lake Valley forms a depression which is a once continuous body (Fig. 2B). The general filled with Tertiary and Quaternary sedimenta- map pattern of the rocks in the region (Figs. ry deposits. Recent movements along the fault 2A, 2B) supports this idea, although there is no zone have tilted these sediments and have dis- evidence that these bodies are not connected rupted drainage (PL 1). at depth beneath Fish Lake Valley. If, however, Ecological Society of America Bulletin, v. 79, p. 509-512, 3 figs., April 1968 509 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/79/4/509/3432501/i0016-7606-79-4-509.pdf by guest on 02 October 2021 510 K. H. McKFK --AGF, MOVIi MF.NT: DKATII VALLFY FAULT '/ONE bordering the southern end of the valley. 'I liliaceous arkosic sedimentary rocks with in- terbcdded basalts and lulls similar in appear- ance to the sequence described above crop out at the mouth ot Horse Thiet Canyon (Fig. 3). 'I here the sequence is more than 1200 feet thick and probably correlates with the deposits at the southern end ol Fish Lake Valley. K-Ar dates have been determined on biotite and sanidine from tuffaccous units in the Fish Lake Valley and Horse Thief Canyon sequences. Two units at the southern end of Fish Lake Valley (Table 1, locality nos. 3 and 4) and one unit Irom the mouth of Horse Thief Canyon ('fable 1, locality no. 5) are Pliocene. The thick arkosic Pliocene deposits at the mouth of Horse Thief Canyon which closely Figure 1. Index map ol the Death \"allcy re- resemble rocks of that epoch in Fish Lake- gion, showing the Death Valley-Furnace Creek Valley, and which probably were derived from fault zone. the same granitic source (Sylvania Mountains), suggest that in Pliocene time the major drain- age in the southern end of Fish Lake Valley was they are separated portions ol the same plu- througll Horse Thief Canyon. At present, how- tonic body, the best restored "fit" would in- ever, Horse Thief Canyon drains about three- dicate right-lateral displacement of the order square miles of the area northeast of the fault of 30 miles. This movement would have taken zone, and none ot the drainage heads in the place since Middle Jurassic time (~ 160 m.y.). granitic rocks of the Sylvania Mountains. An The amount of separation of the granitic adjustment of the drainage, therefore, has bodies is similar to the offset of Precambnan taken place. The change could be due to head- and Paleozoic lacies in the region (Fig. 2). ward erosion on \Villow Wash or to disruption Some details of these lacies relationships have of drainage by faulting. In the latter case, a been described by Stewart (1967, Fig. 5). stream system with Horse Thief Canyon as the Tertiary roc/^s. At the extreme southern end main outlet for the north flank of the Sylvania of Fish Lake Valley, tulfaceous arkosic sand- Mountains can be reconstructed by shifting stone, siltstone, and conglomerate with a few the region north of the Death Valley-Furnace interbcdded rhyolitic ruffs and basalt flows Creek fault zone approximately 3000 feet in a form a continuous section more than 2000 feet left-lateral sense. A divide would then exist thick (Fig. 3). The entire sequence dips away causing the headwater area of Willow Wash to from the Sylvania Mountains, a granitic body dram out Horse 1 hief Canyon rather than TAIU,H !. I\>TASSlUM-Aiu;oN RADIOMF.TKIC DATKS FROM ROCKS i.v THI; KKCION AROUND THE SOUTH FND or FKSII L.\Kii VAI.I,I;Y Locality K2O Ar''10 ° rad Ar« rad no. Lab no. Locution Mineral (percent) (l(P inole/g) (percent) Age (m.y.) 1 KA840 Center sec. 36 T6S, R38H Bioiite 75.4 155 ±3 2 KA902 Vv center sec. 15 T6S, K.37I-: Bioiite 85.5 161 ±4 3 61091 NF, Kscc. 3 T7S, R38L Biotitc 27.96 4.5 ±0.2 4 61090 Center sec. ? T7S, R38E Sanidine 61 .90 3.5 ±0.2 5 61021 NVv'Msec. 17 T7S, R3SF Biotite 25.84 5.7 ±0.2 1 m Xe = 0.585 X 10"'" yr" K. /K. total •= 1.19 X 10 ' mole/mole X/3 -- 4.72 X II)-10 yr ! Argon analysis by standard isoiope dilution (Lab. numbers 61021, 61090, and 61091 run by li. H. McKee using a Neir-typc mass spectrometer at the U. S. Geological Survey Isoiope Laboratory, -Mcnlo Park, California. Samples KA840 anil KA902 run by }• !>• Obradovich using a Rcynolds-lypc mass spectrometer at the University of Cali- fornia at Berkeley, 1961). Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/79/4/509/3432501/i0016-7606-79-4-509.pdf by guest on 02 October 2021 N 4 miles Areal photograph of the south end of Fish Lake Valley. Cucomungo Canyon southeast corner, Horse Thief Canyon west central portion of photograph. Death Valley-Furnace Creek fault zone runs diagonally from northwest to southeast across the picture. McKLL, PLATE 1 Geological Society of America Bulletin, volume 79 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/79/4/509/3432501/i0016-7606-79-4-509.pdf by guest on 02 October 2021 Potass ium-argon 25 Miles age date localities Jurassic and Cretaceous Precambrian and Cambrian Precambrian and Paleozoic granitic rocks r o c K s of rocks of "W h i t e - I n y o " f a c i e s "Death Valley" facies Figure 2. ("A) Present distribution of granitic rocks in the \Yhitc-Tnyo Mountains and Sylvania Mountains. (R) Distribution of granitic rocks in the Invo batholith in Middle Jurassic time. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/79/4/509/3432501/i0016-7606-79-4-509.pdf by guest on 02 October 2021 512 -AC;K, MOVKMKNT: DEATH VALLKY FAULT ZONK iO miles b\ right-lateral movement along the not them part ol the Death Valley-Furnace deck latilt /one. These possibly displaced rocks ha\c the same lithologic character on cither \ - side ol the l.iult zone, and a K-Ar date (155 + °"J \ •Sylv-i i m \ ) on the northeastern side of the fault is \ Mount fish Lake f-\ \ the -ame as a date (161 ±4 m.y.) on the south- Valley ' .