Titus Canyon: The Klare Spring Breccia

Klare Spring in Titus Canyon is well known as a petroglyph site (with a sign and everything); it is less well known as a breccia site and as a place to view the low-angle normal faults of the Titus Canyon fault zone (TCFZ). MOH and I were both immediately attracted to the breccia, and then—after examining it closely—we turned our attention to the various petroglyphs. (If you want petroglyphs, go here, here, or here, or to other Google-able websites.)

The breccia is the orange-brown mass of rock that MOH is inspecting intently. It's composed largely of fragments of Carrara Formation (Єc), with a few scattered chunks of gray limestone, which are presumably from either the Carrara Formation or the tectonically higher Bonanza King Formation (Єb). The upper strand of the Titus Canyon fault zone (TCFZ) cuts above the breccia, somewhere between my Єc and Єb labels, possibly at the base of the first cliff, or possibly behind and above that cliff. Rocks in this lower part look brecciated to me, but I didn't scramble up the slope to see them in person.

In fact, here are some of my ideas about the placement of the upper strand (or multiple upper strands?) of the TCFZ.

An image from Google Earth approximating the first photos.

I wasn't sure whether the two very large angular fragments of gray limestone, including the block festooned with petroglyphs, were an actual part of the tectonic breccia, or whether they had at some point slid down the cliffs and been cemented in place by the waters of Klare Spring.

Angular fragments of the Carrara Formation are healed by travertine.

The waters of Klare Spring emerge from the lower strand of the Titus Canyon fault zone, just down-canyon from the petroglyph site. The lower strand has placed this fractured, shattered, and brecciated Carrara Formation over the older Wood Canyon Formation (ZЄw, see next photo set).

Looking up canyon past Klare Spring.

I happened to shoot this pic looking eastward, back toward Klare Spring from a couple hundred yards down canyon. Once again, I had fortuitously grabbed a view of the TCFZ, this time including the lower strand that runs right through Klare Spring, and also including the upper strand (although the exact location is of that strand(s) is imprecise).

The same view with some geologic labels, including a few question marks.

The faults up the canyon (on the right) were seen in more detail in an earlier post; basically, we're looking at the upper strand of the TCFZ, which has placed the Bonanza King (Єb) over the Carrara (Єc) and some possible breccia (labeled "?"). Klare Spring is past the white car in the lower left of the photo. The lower strand of the TCFZ, which runs right through Klare Spring according to many, places the pale orange brecciated Carrara (Єc bx) over the reddish brown rocks of the Wood Canyon Formation (ZЄw). I've labeled the Bonanza King where I'm sure of it (Єb), and have left the first light gray cliff above the Єc breccia as "?". These lower cliffs, held up by rocks that appear brecciated in the first set of photos, might be composed of Carrara or Bonanza King, or even some tectonic jumble of both.

And so, we've left Klare Spring, and will continue our way down the canyon...

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!)
Scribbles
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
Titus Canyon: The TCFZ, the FCFZ, and a few Other Faults
Titus Canyon: Another Look at the Titus Canyon Fault and A Scramble
Titus Canyon: We Make Our Way Toward Klare Spring

Leadfield: Geology...and a Cactus...on the Way Back to the Parking Area

We've left the far northwest mine building at Leadfield, have sauntered past a large chunk of Tertiary megabreccia (Mbx), and we're making our way back to the parking area by the Leadfield sign.

Looking to the SW, we see part of the broad fold in the Bonanza King Formation juxtaposed against the foreground mass of Mbx.

Wonderful barrel cacti grow right along the trail.

The barrel cactus here is of the genera Ferocactus, possibly the type known as California barrel cactus, or Ferocactus cylindraceus (there is more than one subspecies of F. cylindraceus).

From this same location, we also have the opportunity to see one of the area's several low-angle faults known collectively as the Titus Canyon fault zone (TCFZ). Here's one online version of the TCFZ in map view and cross section. On the map it's shown as a thick, hatched line wrapping around the upland south of Titus Canyon. It crosses the canyon at Klare Spring, and northward becomes the main strand of the Fall Canyon fault zone (FCFZ). I modified the figures by moving the scales, credits, and index map for cropping and added the location of Leadfield to the map. Note the askew north-south line indicated by the 117°00' mark; the long dashed line on the right is the skewed CA-NV border.

Source: Part of Fig. 1 of Reynolds, 1974 reprinted in Troxel and Wright, 1976 at NPS History eLibrary.

Source: Part of Fig. 3 of Reynolds, 1974 reprinted in Troxel and Wright, 1976 at NPS History eLibrary.

Back on the trail, we're looking south toward the low hills.

My labeled version of this photo shows both thrust (thick line with sawteeth) and low-angle normal (thick line with hatch marks) symbols. Reynolds' map (the one in Lengner and Troxel, 2008), shows this fault with a thrust symbol, but it hooks up with one that appears on Google Earth to wrap around the terrain to become part of the larger Titus Canyon Fault system, even though that part of the low-angle fault system doesn't appear on Reynolds' summary map (above) or this composite map (Workman et al, 2002). You can also see this low-angle fault on my marked-up Google Earth image (below); I've got it there with two colors, deep blue and a kind of dark magenta. I should probably just change it all to one color, but when I made the image, I was trying to correlate different strands of the fault system, which I've since determined is a rather futile project without some field mapping and perhaps a bit of surveying, neither of which I'm likely to do!

The low-angle fault south of Leadfield places younger rocks on older rocks, a hallmark of low-angle normal faults; thrust faults (low-angle reverse faults) can also do that, but they more commonly produce an older-over-younger scenario.

Photo with geology from Reynolds (1969, in Lengner and Troxel, 2008).

Although seen here mostly in fault contact, the usual section from bottom up is Cambrian Zabriskie Formation (Cz), Cambrian Carrara Formation (Cc), and Cambrian Bonanza King Formation (Cb). The Eocene-Oligocene Titus Canyon Formation (EOgtc) and batches of megabreccia within the lower part of the EOgtc (Mbx) sit entirely in fault contact with the Cambrian rocks along a normal, down-to-the northeast fault. Landsliding or slumping along this fault or the TCFZ might be what produced the breccia bodies now known as Mbx.

My (current) Google Earth version of the geology at Leadfield.

The geology I've drawn onto Google Earth (GE) is mostly from two maps: North and northeast of the Titus Canyon road, the geology is largely from Niemi (2012); south and southwest of the road, the geology is largely from a map in Lengner and Troxel (2008), which they took from Reynolds (1969). The contacts as transferred to GE should be considered approximate; I've modified them where I've seen fit and added possible faults and a few other things like marker beds.

Let's keep meandering back toward the parking area.

Dried wildflowers, probably from the spring or summer of 2015, grow out of a concrete foundation.

Lengner and Troxel list this former building as "Frame and Iron Compressor and Engine Room," located on Western Lead Mines Company's March Storm claim No. 2. I'd usually just call something like this an old mill foundation.

I paused below the main mine dump, next to the larger metal building that we saw last time, to take two zoomed shots looking eastward across the valley of lower Lost Canyon.

Interesting fracture pattern in greenish brown rocks above the red slope formers of the Titus Canyon Formation. Is that tilted columnar jointing? Tilted bedding? Stay tuned.

Reddish bluff (earlier called "Tc Hill") above orange, brown, red, and greenish layers. All the formations are dipping to the north.

When I took the photos, I wasn't thinking of making a panorama, but look! They splice together fairly well with just a tiny bit missing in the middle. All the better to see the geology with.

We look eastward, over the parking area near the Leadfield sign.

With some geology added!

Here we're seeing most of the Tertiary section (Paleogene to Neogene).

The Tertiary section (from Niemi, 2012):
Tm = Miocene Timber Mountain Group (ash-flow tuff)
Tp = Miocene Paintbrush Gp (ash-flow tuff)
Tc = Miocene Crater Flat Gp (ash-flow tuff)
Tw = Miocene Wahguyhe Fm (sedimentary and volcanic rock)
Tg = Miocene Panuga Fm (conglomerate, sandstone, and minor tuff)
EOgtc = Eocene-Oligocene Titus Canyon Fm (various sedimentary facies)

Part of the pre-Tertiary section:
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)

The section is sliced by two major, roughly north-south trending normal faults, part of the Fall Canyon Fault Zone (FCFZ). I've labelled these FCFZ/W (westerly strand) and FCFZ/E (easterly strand), not to imply that these are the only strands of this fault zone. The faults are moderate- to high-angle at the surface, flattening at depth. There is a bit of white rock along the westerly strand of the FCFZ; I'm not sure if this is a fault breccia or shatter zone along the fault or some light-colored bed (tuff?) smeared along the fault, and I'm not sure if it belongs in the hangingwall or footwall. I decided to show it as a possible shatter zone, marked in dashed blue lines.

The fault shown with an up arrow to its right, is a somewhat minor high-angle normal fault with its down side toward us (down-to-the-west); it is not a reverse fault. (I'm afraid the arrow makes it look that way, but I don't feel like redoing the labeling!)

Same photo with a little more labeling.

In the second geological panorama, I've added a few broad orange, pink, and lavender lines or strokes to indicate three marker beds in the Panuga Formation (Tg). These are possibly tuffs. In the geologic image below, the pink and lavender color of the upper two marker beds is reversed (my fault!).

Google Earth image of the same panorama.

The geologic map on Google Earth (same as earlier).

Next time, we'll finally get into the main branch of Titus Canyon!

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.

Reynolds, M.W., 1969, Stratigraphy and structural geology of the Titus andTitanothere canyons area, Death Valley, California [Ph.D. thesis; not available online]: Berkeley, University of California, 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.

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!)
Scribbles
Titus Canyon: The Upper Part of Lost Canyon
Leadfield: Scams with a Side of Geology
Leadfield: Views from Old Mine Buildings

Titus Canyon: The Upper Part of Lost Canyon

As we descend the west side of Red Pass and enter the realm of Titus Canyon proper—as opposed to being just on the Titus Canyon road—the geology becomes a little more complex than the Tertiary-to-the-north–Cambrian-to-the-south scenario that we've been seeing since leaving Tan Mountain. Just for the heck of it, I’ve shown a little of the geologic complexity of the area below, although the contacts I’ve drawn, using Google Earth’s “Add Path” tool, are merely the ones I’ve felt the need to investigate during the course of writing these little blurbs about Titus Canyon: They by no means represent all the geology, nor are they guaranteed to be accurate or precise. And I’ll probably add a few more lines before we reach Titus Canyon’s alluvial fan!

Geologic contacts are in cyan and other colors; faults are thicker lines in dark blue, dark purple, and magenta. Geology is modified from Niemi (2012) and Reynolds (1974, also as seen in Lengner and Troxel, 2008).

On the last bit of our journey along the Titus Canyon road, we had stopped to briefly consider the geology of Tc Hill, and we had nearly reached the sharp turn at the western base of Red Pass. We have now fully entered the southeasternmost branch of upper Titus Canyon.

There are three branches to upper Titus Canyon. The longest branch, the northern or western, runs about 5 miles almost due south from its headwaters near Alkali Spring; this branch is labeled Titus Canyon on topo maps. The second longest branch, the southern or southeastern, runs about 2.5 miles northwest from Red Pass; though unnamed, we're calling this branch Lost Canyon after Lengner and Troxel (2008) and others. A third branch, the eastern or middle, runs about 2.4 miles southwest from headwaters in the volcanic hills near the California-Nevada border; this branch is also unnamed, and I'm not aware of any local or regional designations for it. The three branches meet just below Leadfield.

The three branches of upper Titus Canyon: The main, west or north branch, aka Titus Canyon, is in purple; the unnamed middle or east branch is in yellow; and the unnamed southeast or south branch, aka Lost Canyon, is in red.

At the western base of Red Pass, the road takes a tight curve and heads west-northwest, closely following the dry wash that cuts through this upper section of Lost Canyon. The gradually crumbling, oft-times slumping, but still-steep cliffs of colorful Tertiary beds dominate the skyline to the north. To the south, the rocks are a bit of a mishmash: Though most of the hilly slopes are underlain by several different Cambrian formations, a few irregular and nearly level reddish patches harbor the poorly exposed, lower Tertiary Titus Canyon Formation, and a batch of locally coalescing rocky knobs expose rugged masses of dark gray Tertiary megabreccia.

Beyond the gray Tertiary megabreccia immediately on our left (south), I spy the maroon color often indicative of Cambrian Zabriskie Quartzite (Cz).

Immediately ahead, the road abandons its close proximity to the wash and passes into a half-mile by quarter-mile upland plain painted red by the lower Titus Canyon Formation. It is at just about at this point in the road that I often become fascinated by the cliff to the north and have to stop to take a few more photos.

We've been calling this cliffy hill "Tc Hill" for the reddish brown formation that caps it, although we could have gone with "Tm Hill" for the Timber Mountain Group tuffs that we can't see beyond and above the upper, dark brown cliff.

This is a perfect spot to review the geology, which is basically a faulted stack of Eocene to Miocene sedimentary and volcanic units: Titus Canyon Formation (EOgtc), possible Panuga Formation (Tg?), Wahguyhe Formation (Tw), and one or two ash-flow tuff formations within the Crater Flat Group (Tc).  The contact between the Tw and the overlying Tc is unclear, but it's probably either right beneath the reddish brown cliff labeled Tc, or it's right below the uppermost, thin whitish layer just below that, or it lies below the cream to pale yellow cliffs below the whitish layer. It's too bad that contacts—which are inconstant constructs that can move with changes in stratigraphic nomenclature—aren't drawn across the land!

Tc Hill, with some geologic formations and a few contacts drawn in.

The dark cyan line between the Tg? and Tw might be one strand of the Fall Canyon Fault Zone (a more definite strand is in dark blue), or it might be a regular stratigraphic contact.

This part of the countryside reminds me of those wonderful desert paintings by Georgia O'Keeffe.

Red rocks on a pink, yellow, and green slope.

As we traverse this relatively flat area, the road will cross several rills and washes coming of the cliff to the north.

The road continues on. The contact between the lower Titus Canyon Formation and the underlying Cambrian units (that's quite an unconformity between the Cambrian and the Eocene!) is now almost immediately south of the road, between us and the main dry wash of upper Lost Canyon. As we cross several rills and washes coming off the cliff to the north, we'll pass low slopes of gray Carrara Formation and bulges of dark gray Bonanza King Formation. If we look closely, we might spot a few old workings dug into these older formations, hinting that we're getting close to the old mining camp at Leadfield.

Now, as we near the end of the reddish upland, the road swings wide and to the south, and we're suddenly aiming toward a lumpy hill of dark gray rock. This is one of several large bodies of megabreccia composed of limestone fragments and blocks (limestone and dolomite?), which lie at or near the base of the Titus Canyon Formation. Stock and Bode (1935), who described and defined the Titus Canyon Formation shortly after H. Donald Curry's discovery of a Titanothere in what became known as Titanothere Canyon (Protitanops curryi, now part of the Brontothere family; read more about this story at Geotripper), included the "limestone breccia" as a basal part of the larger Titus Canyon Formation. In the many times I've driven by these breccia bodies, I've always assumed they were part of the Paleozoic section of the area! Next time...

The reddish road, pointing toward a jumble of dark gray rocks in this Google Earth ground-level view, is about to make a tight turn to the right.

This tight turn signals that we are about to descend into the Leadfield part of Lost Canyon, and that we are nigh onto the roughest part of the road.

Now that we've passed this tight curve, the road has a steep drop off to the dry wash immediately to the left. Across the wash, there's a great view of one of the larger dumps of the Leadfield mining camp.

A partly wash-eroded mine dump sits below a large, dark gray outcrop of Tertiary megabreccia. Cambrian Zabriskie Quartzite forms a maroon cliff in the upper part of the photo. 

I was a little surprised to find that the oldtimers were digging into what's long since been determined to be monolithologic breccia formed of angular clasts and blocks of Bonanza King Formation, that is, not the Bonanza King Formation itself. Although I haven't examined this working in the field, I'm going to note a few things from the photo as though I was looking at it from an exploration standpoint. First, a bit of a hedge: It's very hard to tell what the oldtimers were after without actually making a visit to the site (all I've ever done is drive by).

A first thing to note is that there is a fair amount of iron oxide on the dump—and on the rock outcrop immediately to the right of the dump, and also on the slope coming off of the Fe-oxide-barren dark gray carbonate breccia (reportedly the breccia might consist of both limestone and dolomite). The iron oxides consist of goethite, hematite, and jarosite based solely on the color seen in these photos (hopefully the color balance of the photos is good), the oxides are leaning toward goethite and jarosite. (Here, I'm using the old porphyry copper, Bear Creek–originated triad of hematite-goethite-jarosite, even though jarosite is technically a sulfate, not an iron oxide. Someday I'll have to try to do a color triangle to show what we used to use.)

Secondly, I'd like to note that someone took the time and effort to shore up the flat area in front of the adit feeding this dump with fairly cruddy hand rocking (left of the dump and best seen in my next photo).

Here you can see the dump and rock wall a little better. The adit opening is behind a largish creosote(?) bush.

Oldtimers were interested in a number of things, just like we are today. They would have been more attracted to the rocks with iron oxides, although iron oxides by themselves aren't indicative of anything besides the oxidation of iron, and iron oxides aren't necessarily all that uncommon in carbonate country. The oldtimers would have liked any quartz vein material they might have seen floating around, and they would have noticed any gossanous material that might indicate the weathering of sulfides. They also knew how to follow structures. Adits, like the one that created this mine dump, were often dug to either follow structures or to intersect them.

The biggest anomaly I see in the photo is the abrupt, semi-linear contact between the unoxidized, cliff-forming dark gray rocks and the oxide-bearing, slope-forming grayish orange rocks. It's possible that the oldtimers were trying to hit this contact. Maybe there was a little indication of "mineral" upslope, maybe not. It's a little hard to for me to imagine that this particular dump was created solely as part of a stock scam, as has often been claimed for nearly the entirety of the Leadfield camp.

That is, if I was doing any exploration in this area (I don't conduct exploration in National Parks or Monuments; it doesn't pay), I'd be remiss if I didn't take at least one sample from this dump, and if I didn't try to find something to sample either in the back or ribs at the adit opening, or on the hill above it. Maybe I'd only try to grab (select, or "high-grade") a sample of iron oxides in blebs, veinlets, or on fractures. I'd also be remiss if I didn't at least look for a "goody pile" left by the last claimholders, although erosion by the wash might have taken it away.

So much for armchair exploration! Here's a bit of the geology near the adit:

Cbl = Cambrian Bonanza King Formation (should be "Cb or Cbk"); EOgtc = Eocene to Oligocene Titus Canyon Formation; Mbx = Tertiary/Paleogene, probably Eocene megabreccia in or at the base of the EOgtc.

After rounding the next bend, we'll be descending into the lower part of Lost Canyon...into the Leadfield basin. The road is on the side of a fairly steep, rocky hill, and we come to what is probably the worst part of the road overall: the part where you might get high-centered if your clearance isn't good enough or if you hit it at the wrong angle.

The road passes over a barely scraped, overhung exposure of Tertiary megabreccia.

We descend, switch back to the south, and there's a great pullout for hiking back to the mine dump and adit we just viewed.

From this trailhead you can hike the short distance to the mine dump we just viewed, and one or two other dumps along the way.

Most mine adits and shafts don't have all these hazards, but most have a few to several. Don't go in if you don't know what you are doing, and don't assume you know what you are doing. It's my humble opinion that you don't.

Well, there we are: We've arrived in the lower part of Lost Canyon, in the valley or basin that the ghost town of Leadfield occupies.

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.

Reynolds, M.W., 1969, Stratigraphy and structural geology of the Titus andTitanothere canyons area, Death Valley, California [Ph.D. thesis; not available online]: Berkeley, University of California, 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.

Snow, J.K., and Lux, D.R., 1999, Tectono-sequence stratigraphy of Tertiaryrocks in the Cottonwood Mountain and northern Death Valley area, Californiaand Nevada, in Wright, L.A. and Troxel, B.W. eds., Cenozoic basinsof the Death Valley region: Geological Society of America Special Paper 333, p. 17–64.

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!)

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

Onward! Onward! How far will we get this time?

Coaldale, as seen in August, 2010.

With Boundary Peak still in view, MOH and I rounded the corner at Coaldale Junction, and pulled in briefly at Coaldale. This particular ghost town, which was first a small mining town and later a roadside waystation with a tiny population, holds a few minor memories for me, dating back to my early days at Northern Exploration Company in the late 70s and early 80s. For some reason, it always seems like a depressing place to stop, and I can rarely bring myself to take a photograph or to get out of my vehicle to take a close look. This time was no different, so I've uploaded a photo I shot back in 2010.

A few miles on, we pulled in at Black Rock, a spot which may originally have been just a little prospect pit in some black chert of the Ordovician Palmetto Formation, but which is now a semi-convenient place to stretch your legs (although it doesn't really offer much cover as a pit stop, and the Millers rest area and the town of Tonopah aren't too much farther down the road).

Coming to Black Rock from the west, Google Street View.

Lone Mountain as seen from Black Rock, looking ESE.

From the south side of Black Rock, we had a good view of Lone Mountain beyond the playa and salt flat of the southwestern end of Big Smoky Valley. A tiny bit of the Weepah Hills is in shadow off to the right (west).

A closer view of the southwest to northwest side of Lone Mountain.

In this photo, the lighter colored rock formation toward the right (west) is the ЄpЄ Reed Dolomite, which, as I noted earlier, is usually listed as Precambrian or Precambrian to Cambrian, and sometimes as Cambrian only. Here it's on top of a thin, dark section of Precambrian Wyman Formation. Underneath the Wyman, and to the left (east), the Cretaceous Lone Mountain pluton forms the bulk of Lone Mountain.

A couple ways in which the Cretaceous may have intruded the Precambrian so sharply and neatly are developed by Maldonado (1984) in the explanation of his map of the Lone Mountain area. I personally think the contact is structural: a low-angle fault (detachment, anyone?), and, in fact, the area is noted as being part of the Silver Peak-Lone Mountain detachment system (Oldow et al, 1994) or Silver Peak-Lone Mountain extensional (or core) complex (Oldow et al, 2009). Also, this map shows the contact as a detachment fault  (Hulen, 2008, between pages 4 and 5). In the few places that I've seen the Wyman-pluton contact on Lone Mountain, I've noted shearing, faulting, or other complexities—and along the north and west side of Lone Mountain, the top of the pluton looks somewhat planar from a distance, and other planar features (jointing?) are apparent from some angles. If you're driving by, a good place to pull off to see these planar features (I'm really not sure what they are) is at the turnoff to the dirt road going to the northern Gilbert mining district a few miles east of Black Rock  (Google Maps location).

Google Earth image from the perspective of between Black Rock and the turnoff to the northern Gilbert district, and up in the air a bit.

Approximate mapped contacts of the three major rock formations, from Maldonado, 1984.

The same image with a few pink lines added.

I'm not sure what the pink lines represent, other than that they are supposedly entirely within the Lone Mountain pluton. They may be joints in the pluton; they may be Tertiary lamprophyre dikes, as on the 1984 map. Another possibility is that the intrusive-sedimentary contact is mixed, like it is on Mineral Ridge, where Wyman and intrusive rock alternate near or just below the detachment fault (or detachment faults). Or maybe all three possibilities come into play. These are just a few ideas to take with you if you happen to go hiking in the area.

Turning back toward the highway, I stumbled across a few interesting rocks.

Breccia.

The rock is a veined and brecciated chunk of Ordovician Palmetto Formation—chert or siliceous mudstone to siltstone. While walking around, I wondered what the remnant of an old mine dump was all about. Maybe this rock holds a clue.

Here's a zoomed in view of the same rock, focusing in on the quartz vein right and center.

The quartz vein contains brown blades of a relict mineral that has now gone to iron-oxide and silica. Possibly the mineral was calcite, and if so, the resulting mineral or texture is often referred to as "bladed quartz" or "bladed quartz after calcite," or more properly, "quartz [or silica] after bladed calcite." The texture can be indicative that you're in the right part of an epithermal system to find an economic gold or silver deposit. Most of the quartz after calcite I've seen has been crystalline; this silica is microcrystalline.

In fact, several smallish gold deposits have been found in the immediate area, and one has been mined (so far only one deposit has been considered economic).

The Boss mine, a small gold deposit mined in the late 1980s, can be seen just across the road from Black Rock.

A zoomed-in view of the open pit area of the Boss mine.

The Boss produced about 32,000 ounces of gold from 600,000 tons of ore (Diner and Strachan, 1994). That would mean the ore grade was about 0.053 ounces Au per ton (o.p.t). The other deposits, including the Black Rock zone, are described here and here, along with the geology of the Boss mining area. Gold is reported to occur mostly in both Tertiary rhyolites and andesites.

And that will be it for 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

Selected References:
Diner, Y., and Strachan, D.G., 1994, Geology of the Boss mining area, Gilbert district, Esmeralda County, Nevada: Econ. Geology v. 89, no. 5, p. 1176-1182.

Hulen, J.B., 2008, Geology and conceptual modeling of the Silver Peak geothermal prospect, Esmeralda County, Nevada: unpublished report for Sierra Geothermal Power Corporation, 23 p.

Maldonado, Florian, 1984, Bedrock geologic map of the Lone Mountain pluton area, Esmeralda County, Nevada: U.S. Geological Survey Map I-1533, 1:24,000.

Oldow, J.S., Elias, E.A., Ferranti, Luigi, McClelland, W.C., and McIntosh, W.C., 2009, Late Miocene to Pliocene synextensional deposition in fault-bounded basins within the upper plate of the western Silver Peak–Lone Mountain extensional complex, west-central Nevada: Geological Soc. America Special Papers 447, p. 275-312.

Oldow, J.S., Kohler, Gretchen, and Donelick, R.A., 1994, Late Cenozoic extensional transfer in the Walker Lane strike-slip belt, Nevada: Geology v. 22, no. 7, p. 637-640.

Strachan, D.G., 1988, Economic geology and exploration potential of the South Boss prospect, Boss gold mine, Esmeralda County, Nevada: unpublished report on file at Nevada Bur. Mines and Geology, 11 p. and notes.

Going to Majuba Hill Soon!

MOH and I will shortly be off on a field trip to a few nearby localities, including Majuba Hill, reportedly a great mineral and rock collecting site, seen here from I-80 looking northwest across Rye Patch Reservoir.

I might try posting from the field with pictures from my phone, but phone photos post at a size slightly too large for my blog styling, and they definitely are not as good as pictures I'll be taking with my camera. So we'll see if I try this somewhat time consuming activity.

Majuba Hill, besides having a wide range of economic elements including copper, tin, and uranium (I also hear there may be gold and silver), has been exposed to several intrusive events, and several varieties of breccia have been recognized. Read more here.

Selected Reference
Trites, A.F., Jr., and Thurston, R.H. (1958), Geology of Majuba Hill, Pershing County, Nevada, USGS Bulletin 1046-I: 183-203.

Fault Breccia on Slickenside Ridge

Up above our last hiking stop on Slickenside Ridge, MOH and I came across this wonderful exposure of a breccia (hiking stick for scale).

Here's a closer view, showing massive and drusy quartz cementing  the breccia and filling vugs left in the rock.

This is a type of fault breccia — though I was so into my admiration of the breccia that didn't think to look for the fault  — and you can see hints of slightly oblique slickenlines on the smooth upper surface in the first photo.

In fact, it just occurred to me to show you what I mean, so here are two photos of that upper surface, one without drawings, one with.

Planar fault surface from the 1st photo, enlarged.

Same photo with some lines drawn in.

The possible slickenlines in the upper left are the ones I noticed first; the second possible slickenline direction shown in the lower right is vaguer, might be my imagination. More field work required!

A zoomed view of the "best" part of the breccia.

Looking northwest toward Winnemucca Mountain (hidden from view by my choice of framing).

Now I've walked back over to the spot where I left you in the last post, looking down Water Canyon toward the northwest. Just above the bright reddish orange dike rock on the right side of the photo, on the hill across the canyon, you can see the lower part of a rock wall first mentioned in this early post about the dikes.

Looking back down the hill and across the canyon.

And so now, as we turn to head back down the hill, we might think about investigating the rock wall on the far hill, the one we sometimes call "Dike Hill."