Two diamictites, two cap carbonates, two δ13C excursions, two rifts: The Neoproterozoic Kingston Peak Formation, Death Valley, California
A. R. Prave Crustal Geodynamics Group, School of Geography and Geosciences, University of St Andrews, St Andrews, Fife KY16 9ST, UK
ABSTRACT Stratigraphic mapping of the Neoproterozoic glaciogenic Kingston Peak Formation (Death Valley, California) provides evidence for two temporally discrete extensional deformation episodes. These episodes are bracketed by the Sourdough Limestone and Noonday Dolomite, the facies characteristics and δ13C data (ranging between 2.15 and –2.56‰ and –1.88 and –4.86‰, respectively) of which make them equivalent to Sturtian and Varangian age cap car- bonates, respectively. This constrains the two extensional episodes along the southwestern margin of Laurentia to ca. 700 Ma and ca. 600 Ma. These observations and data show that the field evidence for mid-Neoproterozoic breakup and the predictions from tectonic subsidence curves for a latest Neoproterozoic breakup are both correct. Thus, Neoproterozoic plate recon- structions must account for two discrete rift episodes separated by 100 m.y. or more. Confining rifting to within the Kingston Peak Formation thereby places the younger Proterozoic rocks of the southwestern Great Basin in the rift to drift tectonic phase.
INTRODUCTION measured sections) integrated with previous work PROPOSED KINGSTON PEAK The Neoproterozoic breakup of the Rodinian (Harding, 1987; Labotka et al., 1980; Miller, TECTONOSTRATIGRAPHIC supercontinent and subsequent amalgamation of 1985; Swanson, 1982) permits refining the age FRAMEWORK Gondwana is a well-accepted hypothesis. How- constraints and tectonostratigraphic evolution of The marked facies changes exhibited by the ever, the timing of Rodinia fragmentation around the Kingston Peak Formation. Kingston Peak rocks across the Death Valley its Laurentian thorax remains problematic (Dalziel, 1997). In 1972, Jack Stewart proposed o 0 km 30 8 117 W Wood Canyon Formation that late Precambrian diamictite and volcanic NV study area CC base C rocks exposed intermittently along the North CA Stirling Quartzite Johnnie Formation American Cordillera were synrift deposits and ~ y
STY that, because such rocks occurred on both Noonday - Ibex Fms 4 margins of Laurentia, rifting was cratonwide KINGSTON PEAK (Stewart, 1976). Field constraints place this rift- FORMATION Beck Spring Dolo. ing at 700–800 Ma (Bond et al., 1985; Ross, Death Valley Crystal Spring Fm WR 1991; Young, 1995), but tectonic subsidence Group Pahrump (1.08 Ga diabase) Panamint Mountains 0 curves imply a much later final thermal event, ca. km 1.7 - 1.4 Ga basement }~ST "_`a YZ a [U
STY 550–600 Ma (Bond and Kominz, 1984; Levy and SU measured section Christie-Blick, 1991). Either two discrete rifts or o Black Mountains 36 N Kingston Peak Fm outcrop protracted rifting occurred (Bond, 1997; Young, 1995). The purpose of this paper is to present RC newly obtained data on the Neoproterozoic WC GW VS glaciogenic Kingston Peak Formation in the LM NR Kingston Death Valley region of California that support the CM Range JH model for two discrete rifting episodes and pro- TH BC FR AH vide ages for Kingston Peak glaciations. HS Panamint Mountains S.Death Valley SP SA VJ HM Wildrose Garlock fault SS "un-named ls" KP3 STRATIGRAPHIC DATABASE SH Mountain Girl DL SC The Kingston Peak Formation is typical of the Middle Park
South Park KP2 inferred synrift glaciogenic rocks preserved along Sourdough Ls Avawatz Silurian Hills o Surprise KP1 Mountains 116 W Northern Facies the North American Cordillera. It is as thick as Limekiln Spring Southern Facies 3 km, exhibits abrupt facies and thickness changes, contains diamictite, and was deposited Figure 1. Kingston Peak Formation outcrop belt, Death Valley in a diverse suite of environments ranging from region; Neoproterozoic succession is upper right and Kingston braided fluvial to glaciomarine (Labotka et al., Peak terminology is lower left. AH—Alexander Hills; BC—Beck Canyon; CC—Chloride Cliff; CM—Crescent Mine; DL—Dog-leg 1980; Miller, 1985; Wright et al., 1976). An age of Wash; FR—Fatzinger Ridge; GW—Goler Wash; HM—Horse Thief ca. 700 Ma is generally assumed, but this is only Mine; HS—Horse Thief Spring; JH—Jupiter Hill; LM—Lotus Mine; loosely bracketed between the 1.08 Ga diabasic NR—southern Nopah Range; RC—Redlands Canyon; SA—Sara- sills in the underlying Crystal Spring Formation toga Hills; SC—Sheep Creek; SH—Silurian Hills; SP—Saddle Peak Hills; SS—Salt Spring Hills; SU—Surprise Canyon;TH—Talc Hills; (Heamann and Grotzinger, 1992) and the base of VJ—Valjean Hills; VS—Virgin Spring Wash; WC—Woodlands the Cambrian, located 2 to 3 km stratigraphi- Canyon;WR—Wildrose Canyon. Note that several sections are too cally above (Fig. 1). My database (29 mapped and close to plot individually at this scale.
Geology; April 1999; v. 27; no. 4; p. 339–342; 4 figures. 339 region have hindered construction of a unified southern Black Mountains–Kingston Range areas youngest Kingston Peak unit, the Wildrose stratigraphic framework. In the Panamint Range, consist of nearly identical lithologies; the only Diamictite, defines an angular unconformity the Kingston Peak Formation consists of a vari- difference is that the rocks in the Panamint Range that seals a Precambrian normal fault. The base ably thick lower succession of coarse siliciclastic are amphibolite grade. Both successions are of the Wildrose Diamictite bevels across older and diamictite deposits (the Limekiln Spring and floored by unconformities and are typified by Kingston Peak units (including an olistostrome) Surprise Members) overlain by a heterolithic suc- carbonate-clast dominated diamictites, olisto- and the fault to rest depositionally on basement cession, including a patchily developed diamictite stromes containing enormous blocks and/or gneiss in the area of the Lotus Mine (LM, Fig. 2, (Sourdough Limestone–South Park Member). In lenses of dolostone and older Crystal Spring dia- A and B). In places, the fault was active during the Silurian Hills (SH, Fig. 1), it is mostly base- base, and irregular mafic igneous bodies. Both initial Wildrose Diamictite deposition (lower ment-clast bearing diamictite and turbidites also display unequivocal evidence for syndeposi- Wildrose rocks are faulted against Limekiln (Southern facies of Troxel, 1967), whereas in the tional extensional tectonism, i.e., buried normal Spring–Surprise rocks), but the fault is sealed by southern Black Mountains–Kingston Range area faults, abrupt thickness and facies changes, and upper Wildrose units and the base of the Noon- it consists of a lower mudstone, a middle diamic- mid-oceanic ridge basalt (MORB) type volcanic day Dolomite. Elsewhere in Death Valley, the tite, and an upper fanglomerate-turbidite, termed rocks (Lanphere et al., 1964; Troxel, 1966; Noonday Dolomite also seals normal faults KP1, KP2, and KP3, respectively (Northern facies Labotka et al., 1980; Hammond, 1983; Miller, (Wright et al., 1976). This confirms that a second of Troxel, 1966). However, KP1 is genetically 1985). Taken together, and as argued by Miller episode of extensional deformation occurred at part of the Beck Spring Dolomite depositional (1983), these are compelling reasons to infer that least as late as the initiation of Wildrose Diamic- cycle and thus KP2 marks the actual initiation of both successions were deposited coevally during tite deposition, but that it had mostly ceased by Kingston Peak deposition (Prave, 1994). a major episode of lithospheric extension. the time of early Noonday Dolomite deposition. The lower Kingston Peak succession (Limekiln A younger extensional deformation episode Thus, the Kingston Peak Formation contains evi- Spring–Surprise Members) in the Panamint can be similarly documented. In Goler Wash dence for two temporally discrete episodes of Range and Northern facies succession in the (GW, Figs. 1 and 2, A and B), the base of the extensional tectonism. What occurred between these two episodes? In the Panamint Range, the Surprise Diamictite is N Wildrose S Silurian Hills sharply overlain by black, finely laminated car- A (mostly basement-clast base Noonday Dolomite C WRdominated diamictite) RC WC GW LM overlain by Ibex Formation (unit 21) bonates of the Sourdough Limestone that pass ★ Noonday Dolomite gradationally upward into pelites and quartzites ★ (unit 20) "un-named of the Middle Park quartzite, which are in turn Mountain Girl limestone" 300 m (cross-bedded conglom- sharply overlain by Mountain Girl conglomerate, erate and quartzite) an “un-named limestone” (a name adapted from
_`Z[Z \][ YYZ[__` yz~ RW Z[` ^_ |}~RST~ UVWX\][} \[ ^_` XYZ}S |R y y |}~RSTXYZ^_` yz{PQUVW\][[Wildrose Diamictite ~T }SYZ TU yU PV Harding’s [1987] “un-named marble” in Wild- (KP2/3 Southern olistostrome and pC fault; Facies; units 13-19) rose Canyon), and the basement-clast–bearing Middle Park fault is sealed by Wildrose Wildrose Diamictite. About 100 km to the south- (shale and thin-bedded fine sandstone; southward ★ location of samples for east, the Pahrump Group in the Silurian Hills and becomes fine to medium ★ C-O isotopic analyses quartzites) adjacent areas (SH, DL, SS, SC, Fig. 1) is domi-
100 m "un-named limestone" nantly siliciclastic and the Kingston Peak Forma-
}~RSWX}~ y yz ~T STXY !"|}~RSTXYZ^_` yU V !"RSXY^_ |}~TUZ[` !"|}~RSTXYZ^_` y [\]abc (formerly Beck Spring basal Kingston Peak is unconformable "_`a[ tion consists mostly of Southern facies rocks. Sourdough on gneiss and metaconglomerate Dolomite; unit 12) Limestone ★ Correlation of this succession to Pahrump expo- Surprise and Panamint Mountains Limekiln Spring sures elsewhere has long vexed geologists study- (sedimentary-clast domina- ★ location of samples for Mountain Girl conglomerate ted diamictite; local basalts; C-O isotopic analyses (units 9-11) ing Death Valley. My reinterpretation of the quartzite and mudstone) Silurian Hills stratigraphy (corroborated by the Limekiln Spring-Surprise Members are many hundreds of meters thick; Middle Park quartzite (units 7-8) unconformable on C isotope data; see following) indicates that the bases of WR-RC-WC are not exposed or are structurally compromised Crystal Spring Fm (unit 6)
"STYZ_` ab TZ[`a !"RSTXYZ^_` U !"^_` }~ST YZ_` post–Crystal Spring Formation there can be cor- 750 Goler Wash area related unit by unit to the Middle Park–Wildrose B s 1000 b 500 m succession in the Panamint Range (Fig. 2C). The n 45 4-WD track b m sedimentary sole exception (allowing for thickness differ- fault GW contact ences) is that in the Silurian Hills the base of the 65 b Lotus mine Middle Park quartzite is an unconformity (it rests s on Crystal Spring rocks) that must pass into a 1000 lks correlative conformity in the Panamint Range. n b b These correlations imply that the limestone pre- o LM viously interpreted as Beck Spring Dolomite in 75 w w the Silurian Hills (Kupfer, 1960) is actually the n N 25 Pz and T rocks “un-named limestone” of the South Park Mem- c lks 10 ber, and that the Southern facies of Troxel (1967) n n w b w is wholly equivalent to the Wildrose Diamictite (Fig. 2C). This correlation agrees with Miller’s Figure 2. A: Stratigraphic cross section of upper Kingston Peak Formation north-south through (1983) contention that the Surprise Member and Panamint Mountains (see Fig. 1 for locations and abbreviations). B: Simplified geologic map of Northern facies rocks are correlative and older Goler Wash area; note Precambrian fault that trends southwest-northeast through central part of than the Wildrose Diamictite and Southern facies map. Contours are in meters. Units: b—basement; c—Crystal Spring Formation; lks—Limekiln Spring and Surprise Members; m—Middle Park quartzite; n—Noonday Dolomite; o—olistostrome; rocks. Others have contested this correlation be- s—Sourdough Limestone; w—Wildrose Diamictite. C: Silurian Hills section with proposed cause of the observation that, in certain localities Kingston Peak member correlations; bold numbers are stratigraphic units of Kupfer (1960). south and east of Death Valley, Southern and
340 GEOLOGY,April 1999 Northern facies rocks occur in close proximity NSbase Noonday Dolomite (~250 m of lower Noonday) and thus were assumed to be coeval. I have care- C B A fully reexamined many of those localities. My observations indicate that the lateral juxtaposition KP3 STUY |}~RST RSTUXY{|} QRS ~T PQRVWX yzP of Northern and Southern facies rocks is due to erosional incision and not coeval interfingering. incised-channel of 50 m quartzite-clast diamictite
For example, in the Alexander Hills (Fig. 3) (~ 300 m thick) (Wildrose equivalent) Figure 3. Stratigraphic
Southern facies rocks (Wildrose Diamictite Spring Dolomite Beck 500 m cross section (measured equivalent) occur in an incised valley that erodes sections A–C) and map ]^Noonday - (modified from Wright, into and sharply truncates Northern facies units. Alexander Hills KP2 Johnnie Fms 1954) of Alexander Hills T}~ !"XYZ^_`ST yz{|}~PQRSTU V PQRS !"]^_c {|}~QRST yz yzPQWX45 yz{|}~PQRST Z` ~T yzP [\ab yzPUV Thus, the Kingston Peak Formation contains two z{|PQRWestern yz{ Talc mine 70 (Surprise Member equivalent) (AH; see Fig. 1). Note how E temporally distinct diamictite intervals separated D Wildrose-equivalent dia- by a stratigraphic succession (most of the South basement middle Crystal mictite erosionally trun- Spring Fm Beck Spring Dolomite cates underlying Kingston Park Member) marked by a uniform, consistent lower Crystal C Peak units KP1 and KP2. facies character. This implies a period of relative Spring Fm
tectonic quiescence between two pronounced |}~ y yU upper Crystal B KP1 45 episodes of extensional deformation. Spring Fm "Z[_`a*+,-./£¤¥¦§¨$ !"' 0}~TUV\]^_c ¡¢©}~ !"{|QRSTWXYZ]^_`c \b $*+yzPQWX`£¤UVWXYZ[\]^_`abc !"yz{|}~PQRST ` y zPUV[\ab [\abC-O !bc UVW[\]abc 60 N 35 One other stratigraphic issue needs to be re- Acme mine A isotope solved. On the basis of exposures in Surprise samples Kingston Peak Kingston Peak Canyon (SU, Fig. 1), Miller (1987) concluded Fm (KP2-KP3) Fm (KP1) ★ that the “un-named limestone” and lower Noon- 1 km day Dolomite were facies equivalents. However,
!"RSTUXYZ[^_`a U [a my mapping in the southern Panamint Range and Panamint Silurian Hills/ Alexander Hills/ reevaluation of the Surprise Canyon mapping A' ./0 ¡¢§¨©Mountains "YZ[_`a !Z]^`cSouthern$*+£¤VWXYZ[\]^_`abcU !" DeathZ U [\ab Valley Kingston UVRange has documented that the base of the Noonday Noonday Dolomite ca. 600 Ma Dolomite cuts irregularly downsection to rest Wildrose; KP2/3 Southern Facies variably on Wildrose Diamictite or “un-named TU3 limestone” or older units (Fig. 2A). This indi- "un-named limestone" YYYZZZ TT}~ UUUVVVWWWXXX PPQQRRSSUUVVWWXXYY Tzz{{|}~ y y QRWX
}}~~ yyzz{{|| Mountain Girl cates that the lower Noonday Dolomite (a tan, TU2 Middle Park
mostly microbial-laminated dolo[calc]micrite) time Sourdough Limestone and “un-named limestone” (a gray, traction- ca. 700 Ma bedded, sandy, oolitic grainstone-wackestone) Surprise and Limekiln Spring TU1 KP2/3 Northern Facies Figure 4. A: Wheeler diagram are genetically unrelated. Consequently, as else- cartoon for Kingston Peak tec- }~ yz{|KP1 where in Death Valley, the Kingston Peak ZZ__`` For- [[\\]]^^pre-Kingston Peak rocks tonostratigraphic units (TU 1–
~~~~TTTT Z[__`" SSTTYYZZ yyyzzz{{{|||}}}PPPQQQRRRSSS \]^ !"\\]]_`abbcc a PQRUVWX YZ RRSTUXXYZ[ PQVW
"" !!aabbcc TU 3); absolute durations of mation–Noonday Dolomite formation contact is 13 δ C ‰ (PDB) units and hiatal surfaces are unconformable. B -4 -2 0246 not known precisely and are Thus, regional unconformities (and correlative shown schematically. Abso- conformities) can be used to define three lute ages are for Sturtian and Kingston Peak Formation tectonostratigraphic lower Noonday Dolomite Varangian glacials. B: δ13C units (Fig. 4A): TU1—Limekiln Spring–Surprise trends for Neoproterozoic car- " !abcbonate units in Death Valley Diamictite–Northern facies (KP2-3 only)–Sour- Wildrose Diamictite; KP2/3 Southern Facies }~ST TUYZ region. Closed circles are for dough Limestone; TU2—Middle Park quartz- "un-named limestone" Mountain Girl conglomerate & sample sites shown in Figures ite–“un-named limestone”; and TU3—Wildrose Middle Park quartzite 2 and 3; Noonday Dolomite Diamictite–Southern facies. Sourdough samples are from southern Limestone Nopah Range section (NR; see Fig. 1). Open circles refer to CHEMOSTRATIGRAPHIC DATA Silurian Hills data (Fig. 2C). Surprise Diamictite; The C isotope stratigraphy has become a 200 m PDB is Peedee belemnite. KP2/3 Northern Facies
}~STYZ" Z[_` a widely applied methodology for establishing "_` chronostratigraphy in otherwise unfossiliferous or radiometrically undatable Precambrian rocks (e.g., Kaufman et al., 1997). The C isotope data lower Kingston Peak (KP1) (obtained and analyzed following standard tech- niques, e.g., Kaufman et al., 1991) have proven
STY critical in establishing a unified Kingston Peak Beck Spring Dolomite }~STY "Z_` yU stratigraphy and its correlation to other Neo- proterozoic glacial deposits. Heavy δ13C trends (Fig. 4B) mark the Beck Spring Dolomite and KP1 limestones with values to 5.16‰ (most are >3.0‰). Heavy values also characterize the Limestone and Noonday Dolomite, which im- positive values (2.15‰) within 15 m of the “un-named limestone” and Silurian Hills lime- mediately overlie glaciogenic diamictites, rec- base, but the Noonday Dolomite trend remains stone and range between 4.33 and 6.27‰ "_`a (such ord marked[ negative shifts between –1.11 and negative for more than 200 m. These trends and heavy values are rare and this strongly supports –2.56‰ and –1.88 and –4.86‰, respectively. the facies characteristics of the Sourdough their correlation). In contrast, the Sourdough The Sourdough Limestone trend shifts toward Limestone and Noonday Dolomite rocks match
GEOLOGY,April 1999 341 those of Sturtian and Varangian age cap carbon- Laurentia’s southwestern margin that account Lanphere, M. A., Wasserburg, G. J. F., Albee, A. L., and ates. Sturtian cap carbonates are dark colored for two discrete Neoproterozoic rifting events Tilton, G. R., 1964, Redistribution of strontium δ13 and rubidium isotopes during metamorphism, finely laminated dolo(lime)stones with C separated by 100 m.y. or more. World Beater complex, Panamint Range, Califor- values lightest near the base (to –4‰), and be- nia, in Craig, H., et al., eds., Isotopic and cosmic come heavier typically over 1–20 m. In contrast, ACKNOWLEDGMENTS chemistry: Amsterdam, North Holland Publish- This work benefited from discussions over many ing, p. 269–320. Varangian cap carbonates are cream-colored years with John Cooper, Matt McMackin, Bennie laminated dolo(calc)micrites with light δ13C Levy, M., and Christie-Blick, N., 1991, Tectonic subsi- Troxel, and Lauren Wright. I thank Julia Miller and Janet dence of the early Paleozoic passive continental values (to –6‰) for many tens to several hun- Hammond Gordon for freely sharing their data and margin in eastern California and southern Nevada: dreds of meters above the base (Kennedy et al., thoughts and Gerard Bond and Ian Dalziel for incisive re- Geological Society of America Bulletin, v. 103, views. Mike Arthur, Mark Pagani, and Dave Pinkus at p. 1590–1606. 1998; Kaufman et al., 1997). Consequently, I Pennsylvania State University and Tony Fallick at the interpret the Sourdough Limestone and Noon- Miller, J. M. G., 1983, Stratigraphy and sedimentology Scottish University Reactor Research Centre provided of the Upper Proterozoic Kingston Peak Forma- day Dolomite as the ca. 700 Ma Sturtian and isotope analyses and insights. This work was supported tion, Panamint Range, California [Ph.D. thesis]: ca. 600 Ma Varangian caps, respectively (ages by National Science Foundation grant EAR-9305708. Santa Barbara, University of California, 355 p. from Young, 1995). Miller, J. M. G., 1985, Glacial and syntectonic sedi- REFERENCES CITED mentation: The Upper Proterozoic Kingston Peak Bond, G. C., 1997, New constraints on Rodinia TECTONIC IMPLICATIONS, Formation, southern Panamint Range, eastern breakup ages from revisited tectonic subsidence California: Geological Society of America Bul- SPECULATIONS, AND CONCLUSIONS curves: Geological Society of America Abstracts letin, v. 96, p. 1537–1553. Unit TU1 contains compelling evidence for with Programs, v. 29, no. 6, p. 280. Miller, J. M. G., 1987, Paleotectonic and stratigraphic Bond, G. C., and Kominz, M. 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The challenge now is to devise geologically compatible plate configurations for
342 Printed in U.S.A. GEOLOGY,April 1999