Tuesday, June 21, 2016

Approach to Titus Canyon: Up and Over White Pass

Getting past Tan Mountain on the trip down the Titus Canyon road always feels like a milestone to me, not so much because the road gets better—it maybe does get better, for a while, or maybe I just get used to the washboard—but because I've finally made it past the Amargosa Desert into the Grapevine Mountains. (The Grapevine Mountains are part of the much larger Amargosa Range, the mountains that essentially bound the east side of Death Valley. See the image after these two bush photos.)

On this section of our trip, we are not actually in Titus Canyon: We are in some unnamed wash that drains eastward into the northwest part of the Amargosa Desert. Beyond "White Pass," we will at first be in the upper reaches of Titanothere Canyon, still not in Titus Canyon.
A close-up of the same bush, showing the silky, tent-like mass in its branches.
I suspect this bush, growing beneath the hoodoos of Tan Mountain, is Purshia stansburyana (formerly P. stansburiana) rather than its close cousin P. tridentata—Lengner and Troxel (2008) show pictures of this bush growing along the road near Tan Mountain. It's hosting what they identify as the caterpillars of the Fotis hairstreak (Callophrys fotis).
Google Earth image of the Grapevine Mountains with a few labels.
Well, I've torqued this G.E. image around quite a bit, so that the long dimension is parallel to the NW-SE California-Nevada stateline. I've added a crude outline of the Grapevine Mountains, the portion of the larger Amargosa Range that runs essentially from the Daylight Pass Road on the southwest (far left boundary) to Scotty's Castle on the northwest (far right boundary that has tailed upward). The odd shape of the mountains on the right occurs because at about Grapevine Peak, the mountain range as named on maps splits in two, with a little tail running WNW toward Scotty's Castle in California, while the main part of the range runs ENE toward Bonnie Claire and Scotty's Junction in Nevada. If you look closely, I've marked White Pass and Red Pass, and a couple faults. (I hope to talk about these faults in a later post.) If I hadn't torqued the image, it would have looked like this:
(No labels on this one, though.)
"White Pass" as a name is well established in Titus Canyon and Death Valley lore: It's mentioned on several websites, including the NPS's page about Titus Canyon, although it's shown on zero maps (that I could find) and is not listed as a place name by the USGS. Consequently, you not only get a location on the Google My Maps map way below, I'm giving you the location on a topo map:
Location of White Pass and other key localities, courtesy USGS TNM 2.0 Viewer. Labeling done in MS Paint.
White Pass will mark another official milestone on our journey: We will enter the realm of this fairly detailed geologic map. Yay!

Between Tan Mountain and White Pass, the road runs south of several smallish dark brown hills composed of brown volcanic rock above white to pale yellow sedimentary rocks, often tuffacaceous, with intercalated tuffs. The brown, hill-capping formation has been mapped as Tlt, Lithic Ridge Tuff and related felsic rocks, by Workman et al (2002) and as part of Tw, the newly defined Wahguyhe Formation, by Niemi (2012). So it's a little confusing, but with a little research I determined that these brownish cliffs are indeed what has been called a latite flow before (Lengner and Troxel, 2008), with Niemi saying that the latite (he included it in the Wahguyhe) correlates with the Rhyolite of Picture Rock, which is rhyodacitic to latitic. So, when you look north at the dark brown caps, think rhyodacite to latite!
Dark brown latite flow rock caps a hill north of the road.
I took this zoomed-in photo mostly because of the interesting patterns in the talus coming from our dark brown latite flow on the right (and, the sky!).
Moving on, we arrive at White Pass, where we can now see into the northeasternmost part of Titanothere Canyon.
We're looking west from White Pass. The dark rocks to the left (S) are Cambrian; the rocks to the right (north) and straight ahead (W) are Tertiary.
At White Pass, and in fact all along the road from about a mile past Tan Mountain, rocks to the south are all Cambrian while rocks to the north are all Tertiary.
The same photo, labeled with geologic formations (the Tertiary as shown is all from Niemi, 2012).
We'll see more of the Cambrian in a bit. The Tg is the Panuga Formation. Probably some of you will notice that this greenish unit has been included in the Titus Canyon Formation before. We'll see more of this unit on the way to Red Pass, and maybe we'll figure out whether it's Titus Canyon Formation or not. The Wahguyhe Formation (Tw) includes various sedimentary and volcanic units, including sandstone, shale, conglomerate, and tuffs. In places, the Trp, Rhyolite of Picture Rock, often described as a latite flow, is included in Tw. Here I've broken it out as best as I can (and hopefully, correctly!). Overlying the Tw and Trp are various tuffs, mostly ash-flow sheets from the southwest Nevada volcanic field, including those in the Crater Flat Group (Tc), the Paintbrush Group (Tp), and the Timber Mountain Group (Tm, not shown in these photos). All these Tertiary formations are Miocene in age (Niemi, 2012).

Before leaving White Pass, we'll look off a little to the south. These two photos were taken about 7 years apart from almost the same spot. The lighting and clouds are a bit different, the time of day is nearly the same.
Photo taken at about 10:00 am in late February, 2016.
Photo taken at about 10:30 am in early May, 2009.
I guess I'm often inspired by the same rocks and the same angles! The photos both show Thimble Peak (6,381 ft, 1945 m), the thimble-shaped peak on the far left. The dark gray rocks in the foreground on the left are in the Bonanza King Formation; the dark reddish brown rocks in the foreground, center and right (in shadow in the 2nd photo), consist, I think, of the Zabriskie Quartzite; and the layered rocks in the distance consist of the Bonanza King Formation (the gray on Thimble Peak and the dark gray capping the ridge to the right of Thimble Peak) overlying the brown, reddish brown, and gray Carrara Formation. These formations are all Cambrian in age. The normal sequence is Zabriskie overlain by Carrara overlain by Bonanza King. On Google Earth, it looks like the Bonanza King and Zabriskie in the foreground are juxtaposed by a fault.

Okay! Let's move along! We've got to get through this canyon before...well, you're not supposed to camp in the canyon: It's day use only!! (This is really too bad, IMO; there is way too much to see along this road in one day.)

Here's another place I always end up stopping: on the road between White Pass and an unnamed pass between the two branches of upper Titanothere Canyon. We'll turn and look south down Titanothere Canyon.
The alluvial fan in the distance is across Death Valley, beyond Stovepipe Wells.
At about the same point on the road, also looking to the south,you'll see Telescope Peak.
Telescope Peak (11,048 ft, 3367 m) is about 45 miles distant in this shot!
Next time, maybe we'll make it to Red Pass!

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., 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.

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:
Beatty: Old Buildings, A Fold, and Onward toward Titus Canyon

The Approach to Titus Canyon: Amargosa Narrows, Bullfrog Pit, and the Original Bullfrog Mine

Mineral Monday: Close-Ups of Bullfrog Ore from the Original Bullfrog Mine, Nevada

The Approach to Titus Canyon: Tan Mountain

Friday, June 17, 2016

Friday Field Photo: Cannonball Chert

Back in my eastern Nevada field days, I was lucky enough to go on a stratigraphy tour that took me to several good examples of chert nodules in the mostly Pennsylvanian Ely Limestone.
Nicely spherical chert nodules in the Ely Limestone, with 2.5 lb sledge for scale.
In the 1950s and 1960s, R. A. Breitrick and J. E. Welsh described the detailed stratigraphy of the Ely Limestone in the area of Ely and the Robinson mining district (with Breitrick, at least, continuing to work in the area to this day). They divided the formation into mappable units, W through C, bottom to top. (Their units A and B have since been placed in the overlying Permian Riepe Spring Limestone.) The only summary of this stratigraphy I could find online is shown here (Maher, 1995, p. 22).

Several units within the Ely, notably units S, R, P, L, and F, contain cannonball cherts (although I'm not sure about the details of units T, U, V, and W: I can't find my field sheets in the mess my office is currently in!). Theses photos are most likely from S, R, or P (my thoughts).
Fairly large, sub-spherical chert nodule.
This is the best example I have of a chert nodule that is approaching "cannonball"  in size and shape. Apparently, cannonball chert nodules can weather out and end up looking a lot like loose cannonballs. An excellent example of a loose cannonball nodule can be seen here on page 27 (Maher, 1995, Fig. 7C).

These photos were taken in the spring of 2007 on the northeastern slopes of Rib Hill, a location that might or might not be accessible from Highway 50 or Route 6 via a side road formerly known as S.R. 44 or S.R. 485 (the location might be behind a locked gate).

Tuesday, June 14, 2016

The Approach to Titus Canyon: Tan Mountain

On our ongoing journey into Death Valley via Titus Canyon, we've left behind the Original Bullfrog mine (which can be seen from the road if you know where to look) and have made it past the eastern boundary of Death Valley National Park. As I've already mentioned, the Titus Canyon road can be distractingly washboardy in its early parts, and it's often barely wide enough for two vehicles to squeeze past each other, which only happens when a faster one wants to pass a slower one (it’s all one-way to the west).
Loose gravel typical of the Titus Canyon road east of Tan Mountain.
In the photo, we're looking back the way we just came, which happens to be northward here, toward some low volcanic hills in the northwesternmost part of the Amargosa Desert.

By the way, I took all the photos in this post in early May, 2009. A lot of flowers were blooming in the upper Amargosa Desert and along the Titus Canyon road. We stopped often on that trip, for flowers, lizards, and short hikes. We didn’t stop as often during our February trip to Death Valley: We were intent on getting to the lower elevations to see the superbloom.
Prickly pear cactus, which we saw along the road before entering the park (see location map way below). The cross-hatching pattern of the pads reminds me of the mineral alunite.
A close-up of the same plant.
An unidentified flowering plant with 1996 dime on the left for scale.
After about 50 minutes on the road, and about a half hour into the park (including flower-photo stops), MOH and I pulled over at a hill composed of exposed and outcropping ash-flow tuff. I found out later that this hill or butte is locally or colloquially known as “Tan Mountain.” It’s referred to by this name on Panoramio and in Death Valley's Titus Canyon & Leadfield Ghost Town by Lengner and Troxel (2002, 2008). The reason for the name is ... you guessed it, the color. It is not named on topo maps, and ordinarily, without knowing a local name, I'd call it hill 4915, for the 4915-foot marking shown on the Daylight Pass 7.5' quad (USGS TNM 2.0 location).

The road is widened somewhat at Tan Mountain, so it's easy to stop, look around, and go for a stroll. It can seem kind of warm on the slopes, even before ten in the morning; maybe the light-colored tuff reflects a lot of heat.
Tan Mountain, with geo-type hiker for scale.
We continued to take flower photos as we rambled upward.
An unknown yellow flowering plant with dime for scale.
Bright red fireweed on the slopes below the rounded spires and hoodoos of Tan Mountain.
Nearing the base of the cliffs, I stopped to take this photo of an outcrop of the pumiceous, lithic-rich, poorly welded ash-flow tuff that makes up Tan Mountain. I didn't climb to the top of the hill, so I didn't get to see if the degree of welding changed significantly in the 200 feet or so to the top.
A reddish brown lithic fragment in the poorly welded tuff.
Tent-like and hoodoo-like forms eroded into the ash-flow tuff.
I'm not sure what ash-flow tuff formation this is. It was mapped as Tr--Pliocene to Oligocene felsic lava flows and tuffs by Workman et al (2002), and Lengner and Troxel (2008) implied that it erupted from the Timber Mountain caldera, although maybe they were intending, on page 63, to refer to tuff sheets seen a little farther to the west when they said:
"...you will see volcanic debris only from the Timber Mountain caldera on this trip."
And that's how far we're going down the Titus Canyon road today.

Location map

Related Posts (in order of posting):
Death Valley, "Super" Blooms, Turtlebacks, and Detachments
Death Valley Trip, Part 2: More of the Badwater Turtleback Fault
Death Valley Trip, Part 3: Northward, and over Daylight Pass
Death Valley Trip, Getting There: Wave Clouds beyond the Sierra
Death Valley Trip, Getting There: A Hike to Pleistocene Shorelines

Death Valley Trip, Getting There: Walker Lake, Road Stories, A Bit about Copper, and Some Folds near Luning

Death Valley Trip, Getting There: A Jeep Trail, Folds and Cartoons of Folds, Even More Folds, and Boundary Peak

Death Valley Trip, Getting There: Highway 95, Redlich, Columbus Salt Marsh, and Another View of Boundary Peak

Death Valley Trip, Getting There: Coaldale, Black Rock, Lone Mountain, and the Boss Mine

Death Valley Trip, Getting There: Black Rock to Lida Junction to Beatty

Beatty: Old Buildings, A Fold, and Onward toward Titus Canyon

The Approach to Titus Canyon: Amargosa Narrows, Bullfrog Pit, and the Original Bullfrog Mine

Mineral Monday: Close-Ups of Bullfrog Ore from the Original Bullfrog Mine, Nevada

Monday, June 6, 2016

Mineral Monday: Close-Ups of Bullfrog Ore from the Original Bullfrog Mine, Nevada

I collected this hand sample from the Original Bullfrog mine, Nye County, Nevada, sometime back in the mid to late 1980s when doing recon in the area, then cut and polished it—probably with a company saw and grinding wheel. This specimen is no doubt the best one I still have (a few may have been lost during one or two house moves), although it's been a while since I looked through all my rock boxes. This one photo has already been featured in two earlier posts, here and here.

I've got a few more photos to show you. These zoom in so we can see the size of the shiny ore minerals contained within the rock: v.g. (visible gold) and a silvery-gray silver mineral.
Here's the other side of this same rock.

We'll be focusing in on the lower left.
I've zoomed in here. Can you see the shiny flecks?
Well, it's hard to see them without holding the rock up to the light and waving it back and forth to get the metallic glint, so I've circled the little bits in yellow and light blue (cyan). Yellow is for gold; cyan is for silver.
See them now?
Yes, these are very tiny flecks of native gold and a silver mineral. The silver mineral is probably either acanthite; Ag-bearing tetrahedrite, with Ag substituting for Cu in the solid-solution series with freibergite; or uytenbogaardtite.
Zooming in even farther, we can see the ore minerals without enlarging the photo.
A few of these show up really well.
Next time I get my hands on this sample—I think it's still up in Alaska—I'll see if I can get even better photos.

Tuesday, May 31, 2016

The Approach to Titus Canyon: Amargosa Narrows, Bullfrog Pit, and the Original Bullfrog Mine

We're officially on the Titus Canyon leg of our larger Death Valley trip—a round trip odyssey that will take us to and near a number of places. This section of our journey began with the last post, which was centered around Beatty. I’ll be complementing my February photographs with photos from a similar journey MOH and I took back in the late spring of 2009. So, let's get on with it! We'll begin by leaving Beatty.

There are two ways to get to the Titus Canyon road from Beatty. I usually forget that fact because it's generally been years between journeys into the canyon. Consequently, I seem to end up on this route one time, and that route the next time, alternating routes without really thinking about it. Then I wonder why the road, the signs, and the overall lay of the land don't look the same as the last time I passed through the area.
Beatty's main intersection: a 4-way stop.
We went one way in 2009, turning left at Beatty’s main intersection, which kept us on U.S. 95 as we drove east and then south through and out of town. We passed the dirt turnoff to Fluorspar Canyon (might there be some fluorite up there?) and passed into the Amargosa Narrows. Not far beyond the Narrows, we turned right onto the unsigned paved road to the Beatty Airport, which goes by an obscure ghost town, Gold Center. Airport Road turns to dirt beyond the airport.
The Amargosa Narrows: Precambrian Z rocks crop out on the right, left, and straight ahead.
We went the other way this past February, going straight on Nevada S.R. 374, the Daylight Pass road, at the same intersection. This paved road winds through a bit of the Bullfrog Hills, going by Velvet Peak and Paradise Mountain. It then meets up with Airport Road near the Bullfrog pit of the currently inactive Bullfrog open pit gold mine.
The Bullfrog pit, as seen from the dirt portion of Airport Road, looking across a sea of blooming creosote (from the early May trip, 2009).
The Bullfrog gold mine—AKA the Barrick Bullfrog gold mine—was in operation from 1988 or '89 through 1998, when it produced about 2.4 million ounces of gold from two main open pits, the Bullfrog pit and the Montgomery-Shoshone pit, and from at least one related underground project, the North Extension. Discovery of these ore deposits began in 1982 with St. Joe Minerals Corporation (overall history is described in some detail here, here, and here). The exploration property then passed through several companies in quick succession through a series of acquisitions or buyouts, going from St. Joe to Bond Gold Corporation, then to Lac Minerals Ltd (or LAC Minerals Ltd, depending on the year—this company went back and forth with its name several times in a few years), and then to Barrick Gold Corporation.

The deposit is hosted in Tertiary volcanic rocks, mostly ash-flow tuffs that are cited by Castor et al (1989) as being correlative with the Miocene Timber Mountain Tuff, which has age dates ranging from about 10 to about 15 Ma (Geolex). In fact, the host formation was mapped by Maldonado et al (1990) as the Rainier Mesa Member of the Timber Mountain Tuff.

I had a tour of the Bullfrog pit back in the late 1980s or in 1990, while I was working for Former Mining Company. Bond Gold was probably the operator when I was there, and the mine was just called the Bullfrog mine. We learned then that much of the overall low-grade ore is concentrated in veins, breccias, and stockworks, and we thought at the time the deposit would be fairly difficult to make money at. It later surprised me that a large company like Barrick got involved in the mining. (I have no idea how the economics really played out; so much can depend on the up front expenditures a company has made and the price of gold during production.)

The deposit formed near the end of an extreme extensional event that took place in the area between 11.4 and 7.6 Ma (Castor and Weiss, 1992Weiss et al, 1995; Castor et al, 1999). Although ore is partly hosted in and controlled by structures in the upper plate of the Bullfrog Hills detachment fault, it's not generally considered to be a detachment-related type of ore deposit (although knowledge of detachment faulting and related structural models would be indespensible for making discoveries in the Bullfrog mining district).

A little farther down the Daylight Pass Road, about six miles from the center of Beatty, the Titus Canyon dirt road heads WSW toward the Grapevine Mountains.
Turnoff to the Titus Canyon road.
The Titus Canyon road is a dirt road of variable character, narrow and washboardy in many parts, and entirely one way east to west. It isn't possible to turn around once you get going, and from asphalt to about "Tan Mountain," there are few pullouts. It's possible that one could exit the road in two or more places within this first section, but it's not clear to me that any of these possible exits are really roads.
High clearance 4x4 vehicles are recommended!
Although 4WD is not usually necessary along most sections of the road, high clearance is a must, and 4WD can become necessary at any time (especially during bad weather). I think the road is blocked from the east when bad T-storms or flash flooding are expected, but I'd always want to check the weather to avoid getting stranded during a bad washout, like the kind the Death Valley area experienced in October, 2015.

This is what the October flooding looked like, during and after:

Don't get caught up in one of these!

Somewhere between the Titus Canyon warning sign and the Death Valley sign, you can look off to the north and see some classic Nevada ash-flow tuff formations, in this case tilted moderately along two detachment faults. The visible roads and workings are in the area of the Original Bullfrog mine, a little less than four miles west, as the crow flies, from the Bullfrog open pit.
Tilted volcanic rocks on Bullfrog Mountain (the highest point in the photo), with the Original Bullfrog mine not far left of center.
Wildflowers and creosote are in bloom in this May, 2009 photo. More precise photo and location information can be had by perusing the map near the end of this post.

I got to fooling around, saving this Google Earth image of Bullfrog Mountain from a similar angle as my photo above.
Google Earth image of Bullfrog Mountain.
Then I fiddled a little more and shortly had a geologic map overlay of Bullfrog Mountain. The two USGS maps used here are the Geologic map of the northeast quarter of the Bullfrog 15-minute quadrangle (Maldonado et al, 1990) and the Geologic map of the northwest quarter of the Bullfrog 15-minute quadrangle (Maldonado, 1990).
The same Google Earth image with two kmz file overlays.
What fun! Okay, this was so much fun, I went ahead and made the image match my photo more precisely, and then added a few geologic labels.
The photo, again, for comparison with the image below.
Geologic overlay of Google Earth (G.E.) image, labeled.
This is a good part of the Bullfrog Hills in which to see the results of the extreme extension that occurred in the area during the Miocene, although I'm not sure if its possible to actually place a finger on the main (or secondary) detachment surface. For the most part, the detachment faults are shown on the maps as dashed beneath Quaternary cover. In only three areas is either detachment fault mapped in the hills where we might be able to go look at the fault planes, and in only two places are dip measurement shown, and both sites are in the low hills to the east of the photo and images.

As for the rest of the local geology, the mylonitized lower plate Precambrian rocks are easily reconnoitered in the light colored hill on the far left of my photo (lower left of the G.E. geologic image), and the tilted volcanic section is easily walked in the hills above the Original Bullfrog mine. The main volcanic formations, oldest to youngest (west to east, left to right), are as follows: Ts3, mostly sandstone, shale, and conglomerate; Tql, quartz latite lava flows; Tlr, the Lithic Ridge Tuff; Tbt2, bedded tuff; Tcb, the Bullfrog Member of the Crater Flat Tuff; Tbt3, bedded tuff; Tpc, the Tiva Canyon Member of the Paintbrush Tuff; Tbt4, bedded tuff; and Tmr, the Rainier Mesa Member of the Timber Mountain Tuff. The Op on these maps is the Ordovician Pogonip Group, here consisting of limestone only 60m thick. The Zm consists of Late Proterozoic metamorphic rocks that have mid- to late Miocene cooling ages related to the regional extension.

Bullfrog ore.
The lower trenches at the Original Bullfrog mine used to be a great place to stop when driving through the area. (The location dot in the last image shows the site of the original mine, not the lower trenches; the lower trenches are more easily seen in the last photo as the small color anomaly below the location of that dot.) The easily unearthed quartz-amethyst veins contain v.g. and other neat minerals (see this post and next week's post). Much of the mineralized material was mined out in the 1980s (or earlier?), and a bunch of it was placed on a nearby heap leach pad. I doubt that leaching was an efficient way of recovering gold and silver from this ore, and we used to bemoan the placing of all this great specimen material out to leach. Not long after my first introduction to the area, which was probably in about 1986 or a little later, someone—no, I really can't won't say who—came and scraped the leach pad, removing all the rock in order to recover and melt the gold and electrum down for a wedding ring (at least that's the story I've heard). I visited the area most recently on the last day of the last millennium (depending on when we say the millenium started). I camped on one of the drill roads after wandering around the roads, trenches, and prospects. I didn't find much. If you ever happen to stop by the area, remember that you're probably on patented (private) ground, at least up near the original mine site, although I don't remember seeing any signs.
The Death Valley National Park boundary on the Titus Canyon is marked by signs, a fence, and a cattle guard.
Here's where we'll stop our journey today, right at the eastern boundary of Death Valley National Park (as an oldtimer, I keep wanting to call it a National Monument).

Location map

Related Posts (in order of posting):
Death Valley, "Super" Blooms, Turtlebacks, and Detachments
Death Valley Trip, Part 2: More of the Badwater Turtleback Fault
Death Valley Trip, Part 3: Northward, and over Daylight Pass
Death Valley Trip, Getting There: Wave Clouds beyond the Sierra
Death Valley Trip, Getting There: A Hike to Pleistocene Shorelines

Death Valley Trip, Getting There: Walker Lake, Road Stories, A Bit about Copper, and Some Folds near Luning

Death Valley Trip, Getting There: A Jeep Trail, Folds and Cartoons of Folds, Even More Folds, and Boundary Peak

Death Valley Trip, Getting There: Highway 95, Redlich, Columbus Salt Marsh, and Another View of Boundary Peak

Death Valley Trip, Getting There: Coaldale, Black Rock, Lone Mountain, and the Boss Mine

Death Valley Trip, Getting There: Black Rock to Lida Junction to Beatty

Beatty: Old Buildings, A Fold, and Onward toward Titus Canyon