The Golden Trout Creek volcanic field is a group of basalt cinder cones and lava flows in the Toowa Valley, some 25 km S of Mount Whitney. It is located in the Sierra Nevada east of the Central Valley and west of Death Valley. The closest neighboring volcanic fields are Big Pine to the N, Coso to the SE.
It is one of multiple volcanic fields in eastern California along the boundary between Sierra Nevada block and the Basin and Range Province associated with the Walker Lane. We touched on both the tectonics of the region and associated volcanic fields in our two 2018 Walker Lane posts. The Golden Trout Creek volcanic field got a brief mention in the second post.
The location is quite high and dry, though precipitation varies significantly from year to year. Temperatures are moderate, hot in the summer at lower elevations and quite cold at altitude during the winter. Snow is not uncommon. It is sparsely populated, with less than 300 within 30 km. It is also a recreation destination, though not as popular as some neighboring destinations.
The volcanic field is located in the Golden Trout Wilderness area, part of the Inyo National Forest, just south of Sequoia National Park. The wilderness area is rugged, with high forests and meadows and high hills. It is some 25 km S of Mount Whitney, the highest mountain in the continental United States and 111 km W of Death Valley, the lowest place in North America. Hiking, camping, fishing are all popular recreation activities. The lower parts of the wilderness are high desert, with meadows and pine forests at higher elevations. It is considered bear country, with black bears not uncommon.
Golden Trout Creek (also known as Volcano Creek or Whitney Creek) is a relatively short (14 km) tributary of the Kern River in NE Tulare County, CA. The creek drains an area of the High Sierra Nevada in the Sequoia National Forest. Volcano Creek is a tributary. California’s state fish, the Golden Trout are native to the creek. The Volcano Falls near the mouth of the creek prevents other trout species from the lower river from mixing and competing with trout in this creek. The fish are prized by fly fishermen and protected from overfishing.
The Golden Trout in this drainage have been physically isolated by downstream falls long enough that they have evolved a bit. They were spared glacial action that removed trout in streams at higher elevations. Rainbow trout reentered the Kern River drainage following retreat of the glaciers some 10 ka. The golden trout are closely related to rainbow trout and are typically colored with more yellows and reds than rainbows. Stocking and reintroduction programs since 1913 contaminated golden trout stocks in lakes and other streams. Most of those fish are now golden – rainbow hybrids. Because of the high altitude of this watershed, spawning season starts quick and is very short.
Volcanoes in California are monitored by the California Volcano Observatory. Golden Trout Creek is not listed as a monitored field. Coso volcanic field to the SE is the closest monitored volcanic field.
The Southern California Earthquake Data Center operated by CalTech monitors earthquakes in this part of the state.
Region
There are multiple volcanic fields in relatively close proximity to Golden Trout Creek, the largest of which is the Coso Volcanic Field. The region is also tectonically active.
Two of the largest earthquakes in California in 20 years struck July 4 and 5, 2019. The first quake was a M 6.4 followed by a second M 7.1 the following day. There have been nearly 3,600 aftershocks following the pair of quakes. The larger quake was felt as far away as Los Angeles, San Diego, Sacramento and Las Vegas. There was a M 5.5 aftershock June 3, 2020, and a M 5.8 near Lone Pine, on Jun 24. All of these were relatively shallow at 4 – 8 km depth. Epicenter of these quakes was located in the desert valley 91 km SE of Golden Trout Creek.
As previously mentioned, the closest neighboring volcanic fields are Big Pine to the N, and Coso to the SSE. Big Pine volcanic field is located in the Owens Valley, 91 km N of Golden Trout Creek. It has over 40 vents in a 1,000 km2 area. Most of these are basaltic cinder cones with associated lava flows. There is a single rhyolitic dome. There have been no eruptions over the last 10,000 years.
Coso volcanic field has been active for the last 4 Ma. It contains at least 38 rhyolitic lava domes, basalt cinder cones, and associated lava flows covering 400 km2. It is located some 64 km SE of Golden Trout Creek. Eruptions have produced some 35 km3 of material since activity started, with the most recent activity likely from Volcano Peak cinder cone some 33,000 years ago. There is a geothermal field with fumaroles, hot springs and geysers. It is one of the largest geothermal energy producers in the US. Most of the field is located within the boundaries of China Lake Naval Air Warfare Center.
Volcanoes
Golden Trout Creek is a group of cinder cones in the Toowa valley of the Sierra Nevada. The valley is a high valley, some 2,886 m above sea level. Typical cones in the field are 100 – 200 m above the valley floor. There are four volcanic centers that are part of the field. There was a series of earthquakes Oct 3, 2009, along the eastern edge of the field. Strongest quake was M 5.2. Magma creating Golden Trout Creek erupted through the granitic Sierra Nevada batholith multiple times over the last 743 ka.
The four main vents of the field are all located within a 10 km2 portion of the field. There are also rhyolite domes present E and S of Toowa Valley. From oldest to youngest the vents are Little Whitney cone, South Fork cone, Tunnel Cone, and Groundhog cone. The three oldest vents, Little Whitney, South Fork and Tunnel Cone have all been modified by glacial action. They have been partly buried by glacial deposits, had delicate lava flow surfaces removed, and glacial erratics left on top of lava flows.
Erupted basalts from this field appear to have come from a mantle source that ascended through the thick Sierra Nevada granite in discrete batches. These batches underwent varying amounts of crustal contamination, differentiation, and magma mixing. Depths of these reservoirs are estimated some 10 km above the underlying Moho. The older magmas are more primitive than more recent ones. The eruption rate of the field is two orders of magnitude less than neighboring Big Pine and Coso volcanic fields. This is likely due to a lack of strain in this location, embedded in the Sierra Nevada batholith / microplate rather than at the boundary of the batholith and the spreading Basin and Range Province to the E.
First activity created the Little Whitney cinder cone and lava flows. The South Fork cone erupted 176 ka and produced the largest lava flow of the field, some 10 km long to the W. Tunnel Cone to the N of South Fork (Red Hill) Cone is undated. Its lava flow is covered by glacial deposits and is thought to be only slightly younger than South Fork. The youngest structure is Groundhog Cone, which also produced a lava flow. Both are unglaciated and thought to be 10 – 5 ka old. The lava flow from Groundhog cone traveled 6 km W down Golden Trout Creek, partly covering the older South Fork lava flow.
Little Whitney
Little Whitney is a 120 m high scoria cone overlying two columnar jointed lava flows. The Little Whitney volcanic center is the oldest in the entire field. It is located NW of Groundhog along a tributary valley of Golden Trout Creek. It was also built in five phases but is separated far enough that none of its products interacted with those of the other cones. The first eruptions produced a short, massive basalt from fissures NW of the current cone. This flow is almost 7 m thick, extending some 100 m from the present cone. There is a small canyon buried by the flow. The eruptions took place from vents that erupted a banded basalt that flowed down the displaced stream from the first eruption almost into Little Whitney Meadow. The second set of eruptions produced a massive basalt, up to 10 m thick, perhaps twice as thick in places. The third phase built a small cinder cone on a bedrock ridge. The disproportionately large, elongated crater was at least 10 m deep, measuring 15 x 45 m. A second round of cone building built a small, inner cone inside the original crater. It finally extruded a small basaltic lava flow from the S wall of the older cone.
Tunnel
Tunnel cone formed via a Hawaiian-style eruption along a 400-long N-S trending fissure. This eruption excavated at least three 25-65 m wide craters. Crater walls up to 12 m high were formed by spatter action by the eruption. These flows dip radially away from the crater center, crumble, and form the steep, unconsolidated flanks of the cone.
South Fork (Red Hill)
The South Fork (Red Hill) Volcanic Center also erupted in three phases, with the first building a cinder cone. Flows of basalt form the cone also layered 2 -3 m thick flowed from the W and SW base of the cone along Golden Trout Creek until they disappear under overlying lavas from Groundhog Center. The cone tops out around 200 m above the present stream on the N side and 100 m on the S side. The final phase erupted a plug of basaltic scoria on the S and W rim of the cone.
Groundhog
Groundhog is the youngest vent and does not show evidence of glaciation. It is a 70 m (250 m above the valley?) scoria and spatter cone. There is some discrepancy on the timing of events between the initial survey of the valley in 1950 and a 2017 paper by Browne, et al. There is also some discrepancy in the reported height of the cone. The original survey concluded that eruptions at Groundhog began with two phases of lava flows, with the cone built late in the process. The most recent analysis had the cone built first and lava flows coming later. I have not seen enough to allow me to reconcile the two descriptions. For purposes of this post, I will go with the most recent description.
The eruption at Groundhog took place in three phases. The first was a Strombolian style eruption that built a scoria cone from non-welded lapilli and spindle bombs up to 2 m in diameter. The second phase was a Hawaiian style eruption with lava fountaining that partly capped the cone rim with densely welded spatter and pyroclasts. The third phase had lava destabilizing and breaching the N flank of the cone. Rafts of the cone were carried 7.5 km W to Kern River Canyon. Rafts of non-welded scoria were spread across the lava surface as the flow changed width due to terrain. Rafted welded spatter and pyroclasts stayed intact as 15 m high hummocks. The eruption is dated 59 – 52 ka, after the Tahoe glaciation maximum. Subsequent Tioga glaciers did not extend to the Toowa Valley floor to modify Groundhog deposits. The original cone was up to 60 m taller than its current height. There is some inward slumping of large blocks just inside the crater that suggest a partial collapse of the cone after it was built.
The cone is a typical monogenetic cinder cone with scoria, ash and bombs. Spindle bombs up to 2 m in diameter are found. Lavas from Groundhog flowed W hugged the N side of the Golden Trout Creek valley, displacing the stream. The flow continued more than 6 km down Golden Trout Creek canyon within a couple hundred meters of the Kern River. The gorge at the confluence of the Kern River with Golden Trout Creek was almost completely filled with lavas from the initial eruption. Since the initial eruption, Golden Trout Creek has cut a new gorge 30 – 90 m deep on the N edge of the older valley, exposing the layered basalts. Here the stream drops over a 30 m tall falls. Immediately upstream, 12 – 14 flows are interbedded with eroded rock from the stream. These piles are 80 – 100 m thick and show columnar joining. All a’a erupted had pressure ridges and gas blowouts. The forward edge of the flows are 2 – 8 m high along a flow front nearly 11 km long. The forward edge is broken and blocky with blocks a meter in diameter not uncommon. Some of these flows overlapped those from the South Fork Volcanic Center.
Rhyolite Domes
There are four rhyolite domes located E of the main Golden Trout Creek volcanic field. Three of these, Templeton, Little Templeton, and Monache Mountains are all rhyolite dated around 2.4 Ma. The fourth Long Canyon dome is much younger, more silicic, extruded at the head of Long Canyon around 200 ka. The Long Canyon dome produced relatively young deposits of pumice exposed by stream erosion.
Templeton and Little Templeton Mountains are conical, constructed of glassy rhyolite on the plain of the surrounding valley. Templeton is 405 m above the valley, 3,000 m above sea level, about 3 km in diameter, with a volume just under 1 km3. Little Templeton is 150 m high, just over a kilometer in diameter, with a volume around 0.05 km3. They are connected by a low saddle. Neither peak has a summit crater or depression. There are no lateral flows present. There is flow banding on both domes.
Monache Mountain is located around 12 km S of Templeton. It is 460 m high, average base diameter of 2.6 km, with a volume just under 1 km3. It is of similar age to Templeton and likely erupted around the same time. It is a single conical hill, similar to the Templeton domes. The domes are built on valley sediments.
The Long Canyon dome and tuff ring is located about midway between Templeton and Monache. It is a tephra ring surrounding a flat-topped dome 100 m above the surrounding plain, with a base diameter of 900 m. Calculated age is 185 ka. The tephra ring is eroded similar to nearby early Wisconsin glacial moraines. Bombs up to a meter in diameter can be found on a nearby ridge. The dome blocked the path of a stream which subsequently cut a path through the side of it, exposing interior layering.
Tectonics
The overall tectonics of this part of California is driven by the Walker Lane, which takes about a quarter of the motion and energy of the northern motion of the Pacific Plate. This is due to the East Pacific Rise coming onshore in Western Mexico some 12 Ma and conversion of that motion from an E-W subduction motion before 12 Ma into the strike-slip motion we see today. About three quarters of the motion and energy are expressed along the San Andreas fault system. The rest of the motion is opening up the Walker Lane, generally along the eastern edge of the Sierra Nevada microplate.
The other thing that is going on is the overall extension of the Basin and Range Province of western North America. This extension began when the subduction of the ancient Farallon Plate was finished and the motion switched from subduction to strike-slip. The edge of the Basin-Range Province abutting the Sierra Nevadas is referred as the Walker Lane and Eastern California Shear Zone. Its primary tectonic motion is strike-slip generally NNW – SSE.
The opening of the Walker Lane has triggered significant intra-continental volcanic activity generally to the E of the Sierra Nevada. Golden Trout Creek Volcanic Field is located within the confines of the Sierra Nevada microplate. As such, magma sourced rises through the entire microplate. This explains the relatively low volume of volcanism here. Magma source is multiple mantle batches, some 10 km above the Moho. Most of the magma erupted is juvenile, though there are at least four rhyolite structures in close proximity east of the field. There is no single magma source powering volcanism in the field.
We discussed tectonics of the Walker Lane along with associated volcanic fields in our two 2018 posts.
Conclusions
Golden Trout Creek is an example of an interesting intra-continental basalt volcanic field. Volcanic activity in the region has been underway since 2.4 Ma, activity in the main part of the field can only be dated back 743 ka with the most recent eruption no more recent than 7.5 ka. Three of the four volcanic centers have been modified by glacial action some 50 ka. The fourth one was active following the retreat of the glaciers. As with most basalt monogenetic volcanic fields, we have a mixture of scoria cones, lava flows, spatter cones, Strombolian and fissure-fed eruptions. In most cases, effusive eruptions took place first. The most recent Groundhog eruption started by building a scoria cone. Flowing water in and around the valley of the field cut exposures into both the lava flows and volcanic cones. While this field is only 746 ka, the lack of recent activity has it classified as a minor risk for future eruptions.
Additional information
Smithsonian GVP – Golden Trout Creek
USGS Volcano Hazard Program – Golden Trout Creek volcanic field
Volcano Discovery – Golden Trout Creek
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