Tuesday, October 11, 2016

Titus Canyon: The TCFZ, the FCFZ, and a few Other Faults

At the end of our last post—the one about the non-fold—we came into Titus Canyon proper and were looking at this view, down the canyon and to the west.

When MOH and I passed through Titus Canyon in May 2009 and February 2016, I didn't know a whole lot about the detailed geology of the canyon: I knew the regional geology of the Death Valley NP, some detailed geology in the Beatty area, and some geologic bits and pieces for the road trip through Nevada, but I didn't know all that much about the geology along the Titus Canyon road. So, although I have some great canyon photos, a lot of the main geologic features in Titus Canyon proper were photographed by accident rather than by design. I've since come to know more of the detailed geology while doing research for the several blog posts comprising this interminably rambling and seemingly unending Titus Canyon series.

Not knowing the detailed geology means that over the years I've driven down the road and through the canyon while missing low-angle faults and a huge fold! The photos we'll see during the rest of the trip were not designed with these geologic features in mind, but because geology is everywhere, we can see portions of these features, including exposures of the several low-angle normal faults known collectively as the Titus Canyon fault or fault zone (TCFZ), which crops out in an area of somewhat more than 4 x 5 miles (about 6.5 x 8 km).
Source: Modified from part of Fig. 1 of Reynolds (1974), which was reprinted in Troxel and Wright (1976) at NPS History eLibrary. North is not up!
On Reynolds' map, I've added magenta coloring to the TCFZ and dark purple coloring to the Fall Canyon fault zone (FCFZ), the Fall Canyon fault (FCF), and what might be the Thimble fault (TF). These faults are all likely related to each other, at least broadly, and the Titus Canyon fault (zone) is explained most succinctly by Niemi (2002):
The Titus Canyon fault, an enigmatic low-angle structure, places upright Middle Cambrian strata on overturned upper Proterozoic through Middle Cambrian rocks ... .
In this instance, upright means right side up rather than overturned or upside down. Like me, Niemi cites Reynolds, both the detailed 1969 version, which I've not seen, and the generalized 1974 version (as in my previous figure). I've seen a version of part of Reynolds' detailed map in Lengner and Troxel (2008); it was particularly helpful in the Leadfield area.

Getting back to the regional map, the main splay of the Titus Canyon fault zone steepens north of Klare Spring to become the high-angle Fall Canyon fault—a single dark purple line trending nearly due north—a fault that cuts rocks at least as young as late Miocene (Niemi, 2012). On the southeast side of the upper plate of the TCFZ, a moderate- to high-angle normal fault—a single dark purple line trending east-southeast—seemingly juts out from beneath the upper plate; it's either cut by the TCFZ or merges with it, I'm not sure which. I think this ESE-trending fault is what's been called the Thimble fault (originally Reynolds, 1969; Saylor, 1991Niemi, 2002).

The rest of the dark purple faults are part of the sensu stricto Fall Canyon fault zone, a set of high- to moderate-angle normal to oblique faults that flatten with depth. Niemi (2002, 2012) explains:
This fault zone is a distinct boundary in the Grapevine Mountains, separating Cenozoic volcanic and sedimentary strata to the east  from Paleozoic miogeoclinal strata to the west [map]. Both the age and amount of displacement on the Fall Canyon fault zone are difficult to determine.
The TCFZ (we first saw a bit of it here) consists of one or more low-angle normal faults that were active during mid- to late Tertiary extension of the region (Reynolds, 1974; Saylor, 1991, Niemi, 2002 & 2012). My improvisational interpretation of Reynolds and Niemi on Google Earth—a little bit farther down in this post—is what we'll mostly be seeing in the next several blog posts.

Keeping all that in mind, let's get back into the canyon!
The first photo with some added geology.
We see a fair example of one of the main splays of the TCFZ in the labeled photo above, over on the right where the Bonanza King Formation (Єb) sits atop Carrara Formation (Єc). This example of the location of the Titus Canyon low-angle fault is from Lengner and Troxel (2008). I was having a hard time trying to place it from Niemi's map until I noticed their Figure 6.17 on page 114 (I recommend their book if you plan a trip through Titus Canyon).

From it's position on the right, the Titus Canyon fault passes in front of us and then to the left, behind the cliffs of Bonanza King. It then wraps around hills we can't see, gets offset once or twice, and becomes (I think) the upper, dark blue fault on the distant slopes. (My correlation of this upper fault with the foreground fault is largely from my interpretation of Reynolds, via Lengner and Troxel, 2008, and my interpretation of Google Earth; this particular fault is not shown on any of the maps I've seen.) I've drawn two splays of the fault system on the background hills. The lower fault as drawn, also not shown on any maps I've seen, partly mirrors Niemi's mapped Єb-on-Єc fault from the north side of the canyon. It's possible that this lower splay doesn't exist. It's also possible that what I've labeled Єb in its upper plate is really Єc, although it doesn't look that way to me (!).

Let's look at this on Google Earth (GE), where I'm storing my geologic mega-cartoon:
My current version of the TCFZ (magenta), the FCFZ and related faults (dark blue), a few other normal faults (blue), the Titus Canyon fold axis (maroon), and several stratigraphic contacts and some formation labels (modified from Reynolds, 1974, Reynolds in Lengner and Troxel, 2008, and Niemi, 2012). 
I have to admit that my interpretation of the location of the main splays or splices of the TCFZ is somewhat hypothetical. I've taken Reynolds' small scale map (here), Niemi's larger scale map (here), bits and pieces from here and there, and created my own mashup based on what I can see on Google Earth. The mashup is far from perfect, and I could change it every time I look at it. (Really, I try to restrain myself!)

As in the earlier geologic map, the low-angle normal faults of the Titus Canyon fault zone (TCFZ) are in magenta; a few possible related faults in the southeast are in dull pink. The TCFZ merges into or becomes the Fall Canyon fault (dark blue) north of Titus Canyon, and may do something similar to the southeast (also dark blue). Other faults in dark blue are part of the larger Fall Canyon fault zone (FCFZ), consisting of high to moderate angle normal to oblique faults that flatten at depth. Other normal to oblique extensional faults in are in lighter blue; some of these might be part of the FCFZ.

The bigger picture in my GE-cartoon includes the Titus Canyon fold, which we'll see more of later, with it's overturned limb west of Klare Spring. The Precambrian to Cambrian section in that area, from oldest to youngest and east to west, is Wood Canyon Formation (ZЄw) overlain by the Zabriskie Quartzite (Єz), which is outlined on the map in thin maroon lines. Above that is the Carrara Formation (Єc), which is overlain by the Bonanza King Formation (Єb). The Carrara – Bonanza King contact is marked by a thin cyan line; it's mostly seen to the west and south of the TCFZ. I've thrown in a rough demarcation line between the pre-Tertiary and Tertiary section in orange. Not drawn in are bits and pieces of the Titus Canyon Formation lying above the Bonanza King Formation, seemingly and quite possibly in the upper plate of the low-angle TCFZ. Labels on the GE image are listed below.

The Tertiary, undivided:
Tvs = Tertiary sedimentary and volcanic formations.

Part of the pre-Tertiary section:
Pz = Paleozoic undivided, including some rocks younger than Єambrian.
ZPz = Upper Precambrian and Paleozoic undivided, mostly Є and pЄ.
Єb = Bonanza King Formation (mostly dolostone with lesser limestone)
Єc = Carrara Formation (mostly siltstone, also quartzite and limestone)
Єz = Zabriskie Quartzite (thick-bedded to massive quartzite)
ZЄw = Wood Canyon Formation (a miscellaneous formation bounded by two quartzites, consisting of siltstone, quartzite, dolostone, conglomerate, and limestone)

I'd hoped to have more photos of the Titus Canyon fault zone in this post, but the geology overcame me! We'll see more next time, when we'll actually, hopefully, go on a little hike.

A Few References:
Lengner, K., and Troxel, B.W., 2008, Death Valley's Titus Canyon & Leadfield ghost town: Deep Enough Press, 175 p.

Niemi, N.A., 2002, Extensional Tectonics in the Basin and RangeProvince and the Geology of the GrapevineMountains, Death Valley Region, California andNevada: Pasadena, California Institute of Technology, Ph.D. dissertation, 344 p.

Niemi, N.A., 2012, Geologic Map of the Central Grapevine Mountains, Inyo County, California, and Esmeralda and Nye Counties, Nevada: Nevada, Geological Society of America Digital Maps and Charts Series, DMC12, 1:48,000, 28 p. text.

Reynolds, M.W., 1969, Stratigraphy and structural geology of the Titus andTitanothere canyons area, Death Valley, California: Berkeley, University of California, Ph.D dissertation, 310 p.

Reynolds, M.W., 1974, Geology of the Grapevine Mountains, Death Valley,California; a summary, in Death Valley region, California and Nevada, Geological Society of America Cordilleran Section, Field Trip 1 Guidebook: Death Valley Publishing Company, Shoshone, California, p. 91-97 [reprinted here].

Saylor, B.Z., 1991, The Titus Canyon Formation: Evidence for early Oligocene extension in the Death Valley, area, CA: Cambridge, MIT, M.S. thesis, 54 p.

Workman, J.B., Menges, C.M., Page, W.R., Taylor, E.M., Ekren, E. B., Rowley, P.D., Dixon, G.L., Thompson, RRA., and Wright, L.A., 2002, Geologic map of the Death Valley ground-water model area, Nevada and California: U.S. Geological Survey Miscellaneous Field Studies Map MF-2381-A, Pamphlet text, Sheet 1, Sheet 2.

Location map

Related Posts:
The Approach to Titus Canyon: Tan Mountain
The Approach to Titus Canyon: Up and over White Pass
The Approach to Titus Canyon: To Red Pass
The Approach to Titus Canyon: Just Below Red Pass
A Hike at Red Pass, Titus Canyon Road, Death Valley, CA
Titus Canyon Road: A Little History and a Few Maps
Down into Titus Canyon: We Leave Red Pass Behind (Finally!)
Titus Canyon: The Upper Part of Lost Canyon
Leadfield: Scams with a Side of Geology
Leadfield: Views from Old Mine Buildings
Leadfield: Geology...and a Cactus...on the Way Back to the Parking Area
Almost Titus Canyon: Is This a Fold? And... Apparent Dip with Post-it® Notes

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