Jordan Craters volcanic field is the youngest of a series of large recent basalt fields in the SE part of Oregon.  It is the northernmost of a group of three lava fields covering 250 km2 over the last 250 ka.  The field elevation is 1,473 m. 

At first glance, the region the field is located in would appear to be relatively boring high western plains, from a tectonic standpoint, it is a busy volcanic region over the last 17 Ma.  To its NW, we have the source of the Columbia River Basalts.  To its immediate E, we have the Snake River Plain and the track of the Yellowstone hotspot.  The field itself is located in the S part of the High Lava Plains of Oregon with the W portion of the extensional Basin and Range Province immediately S and E. 

There are at least three ignimbrites in the immediate region, multiple rhyolite domes, and more than a few intraplate basalt fields.  While caldera activity associated with migration of the Yellowstone hotspot has moved to the NE over the last 10 Ma, smaller rhyolite eruptions are tracking NW in the High Lava Plains.  Basalt activity has been more complex and widespread. 

The area is remote, with less than 30 living within 30 km from the field.  There are over 230,000 within 100 km.  The largest neighboring town is Bosie, Idaho, some 113 km NE, with a population of nearly 765,000 in its metropolitan area. 

Climate is classified as semi-arid continental.  Mean daily maximum temperature in Boise is 18° C.  Mean daily minimum is 5° C, though in the high desert, these temperatures can swing wildly, with record high at 44° C and record cold at -33° C.  Average precipitation is just over 29 cm/year.  Most of it falls as snow.

Boise is located in the Snake River Valley, one of the more hospitable locations in the region.  It was initially populated by natives.  Boise started as a way point on the Oregon Trail and grew based on discovery of gold and silver.  There were no small number of unpleasant interactions between settlers and indigenous people that was settled by 1870.  Current economy includes major corporatioins doing business in Idaho (Boise is the capital of Idaho and its largest city).  Mining and timber are still important to the local economy.

The field supports hiking, camping, and tourism.  Visitors are warned that the area is rugged with precarious footing.  There are few if any trails.  Sharp lava formations and open pits can be dangerous for all hikers.  Temperatures on the fields vary widely, nearly 50° C during the summer.  There is no water and dehydration in the heat is a real possibility.  Roads are nearly impassable when wet.  Winter weather can make access difficult.  High clearance, four wheeled drive vehicles are recommended.  While Jordan Craters is not yet a protected area, there are ongoing efforts at the state and federal level to protect the field at some level. 

Volcano observation and monitoring in this part of Oregon is done by the Cascades Volcano Observatory located in Vancouver, WA.  While the neighboring Yellowstone Volcano Observatory concentrates on Yellowstone, it also provides overlapping coverage.   There is a seismometer and GPS sensor near the neighboring Diamond Craters volcanic field 108 km W.  The nearest dedicated webcam appears to at US 95 at Jordan Valley, 38 km ESE from Jordan Craters.  It is not dedicated to the field. 

Region

We discussed volcanic activity in the Snake River Plain at Craters of the Moon in 2016.  It is a long way from Jordan Craters, over 320 km E.  In the other direction, we took an extended look at Newberry Caldera, another 300+ km W in insert year and link to the post here.  Previous posts took a look at Belknap Crater and the Three Sisters insert year and links to both posts here.  The following volcanic features can be found in the immediate region.  

Rocky Butte (Lava Butte)

Lava Butte is one of three small basalt shields 17 km S of Jordan Craters.  It dates 90 – 30 ka.  Clarks Butte to the N is slightly older at 250 ka.  There is a third unnamed shield to the E.  There are three lava fields immediately S of Jordan Craters which we will discuss later in the post. Lava Butte and Clarks Butte were the source of two of these. A third lava flow erupted from West Crater which is not listed as a separate volcano outside the video and image above.

Saddle Butte

The Saddle Butte volcanic field is located some 32 km SW from Jordan Craters.  It erupted in two pulses, with initial activity covering over 1,100 km2 with basalt.  The second and most recent pulse covered some 240 km2 of the original field.  The second pulse was thought to be very new but has since been dated some 430 ka. 

The field is separated from Jordan Craters by the drainage of the Owyhee River.  It resembles basalt fields of the Snake River Plain in Idaho.  Vents on the flanks of Sheepshead Mountains at the far W of the field produced lava tube fed flows to the E.  The most recent flow in the field created abundant lava tubes including the 40-Mile Cave.  This is part of a tube system 13.5 km long.

Jackies Butte Volcanic Field

Jackies Butte volcanic field has two basalt shields and two cinder cones 61 km S from Jordan Craters.  It is poorly studied and appears to be older than nearby Jordan Craters.  It was reclassified as Pleistocene and removed from the list of volcanoes in the USGS threat assessment.  Lava flows from the vents cover at least 325 km2 E of Bowden Hills.  There is no precise age, though it is estimated at less than 10 ka. 

Sinker Butte

Sinker Butte is a 1,012 m basalt shield and tuff cone in the W Snake River Plain, some 69 km E of Jordan Craters.  The cone has been partly cut by the Snake River Canyon.  Lava flows from the tuff cone flowed up to 10 km S.  The large tuff cone was built on a broad shield.  It is in turn capped with lava flows and welded spatter.  Final activity dates somewhere around 1.2 Ma. 

The shield is the largest hydromagmatic structure in the W Snake River Plain.  The current Snake River canyon cuts its E and S flanks, exposing continuous sections up to 300 m high along a 7 km canyon wall.  Exposures are clean due to scouring by the Bonneville flood 14 ka.  The lowest exposures are a sequence of lava flows covered by as much as 100 m of phreatomagmatic tephras erupted from a large tuff cone.  The tuff cone is in turn capped by welded spatter and lava flows.  Final spatter and lavas may be 2 Ma younger than base lavas, suggesting initial activity somewhere before 3.2 Ma.

Lake Idaho occupied the W portion of the Snake River Plain 12 – 2 Ma, an unusually long time for a Lake Ontario sized lake.  It survived multiple ice age cycles.  It finally drained when the Snake River cut its present channel through Hells Canyon to the Columbia River. 

Activity at Sinker Butte took place toward the end of the lake’s existence.  Initial eruptions here took place 100 m under water.   Most of the initial tephras are hyaloclastites that cover initial pillows on the former lake floor.  Initial activity was underwater, built a cone through a series of phreatomagmatic explosions, ending with Hawaiian eruptions once above the surface.  There are also pillows from the final lava flows showing their interaction with water.  Eruption of the tuff cone took place 400 – 300 ka after the draining of Lake Idaho. 

Mountain Home – Kuna Lava Field

The Mountain Home – Kuna lava field is an extensive field of basalts in the 95 km between Mountain Homa and the Kuna Melba SE of the Boise River valley, some 120 km E of Jordan Craters.  Lavas here have been dated around 2 Ma.  Total volume erupted was around 300 km3 from a group of vents crossing the plain and its boundary faults.  This alignment is referred to as a volcanic rift zone about 100 km long. 

Basalt volcanism in the W Snake River Plain took place in two episodes.  The first was 9 – 7 Ma, immediately following eruption of rhyolite lavas / domes 12 – 9 Ma now exposed along the margins of the plain.  Basalts from the early pulse erupted more times than not in contact with water.  The second pulse took place 2 Ma – present, long after volcanism ended in the central part of the Snake River Plain.  Basalts from this volcanism cover sediments deposited in Lake Idaho.  Chemistry of basalts in the western Snake River Plain was initially different than those in the eastern plain.  Basalts erupted over the last 2 Ma are chemically similar. 

The S part of this extended field at Mountain Home is an upland volcanic plateau above the Snake River floodplain.  Lava flow during construction of this plateau entered the lake, creating deltas of hyaloclastites and pillows.  Farther inland, the lavas are pahoehoe.  These basalts are covered by younger basalts erupted from at least 13 shields clustered near the NE margin of the plateau.  The shields rise 120 – 210 m above the surrounding plateau.  Several of them are topped with central depressions that likely represent former lava lakes.  Cinder cones are the youngest volcanic features.  Several of them may cap small shields. 

Diamond Craters

Diamond Craters is a young basalt volcanic field covering nearly 70 km2 with Pahoehoe and a’a lavas.  It is located 108 km W from Jordan Craters.  The name is derived from the nearby village of Diamond, Diamond Ranch and its diamond-shaped brand.  Eruption site is the confluence of the Blitzen River and Kiger Creek.  The floodplain is nearly saturated these days.  Magma interaction with water took place during its time of activity.

The field was active 7.8 – 7.2 ka.  Individual eruptions took place over a decade or two.  Previous dating found the field younger than 20 ka.  Early activity was from a central fissure or vent.  It covered a circular area nearly 5 km in diameter.  Initial eruptions covered the area with basalt.  Subsequent eruptions injected magma between the underlying soil and new lava crust, inflating it.  The intruding magma also interacted with water, flashing to steam in hydromagmatic explosions, pockmarking the area with explosion craters.  This created an ash blanket nearly 20 m thick near the central crater complex.

There are at least 90 craters, some 50 m deep, 40 – 280 m wide.  Most of these are steam explosion craters.  Some are subsidence / drain back pit craters.  There are a few funnel-shaped craters on the tops of small cinder cones.  Craters accessible by the public have a variety of shapes.  Twin Craters is a pair with blocks of lava a few meters wide on their rims.  Diamond Pond is a 2 m deep pool in an explosion crater.  the underlying crater is at least 30 m deep, filled with sediment.  Water level in the crater is the underlying water table depth for the field. 

Jordan Crater volcanic field

Jordan Craters volcanic field is located in a topographic depression on the Owyhee Plateau, 1,200 – 1,400 m.  There are at least six basalt flows in the region.  The original region was part of the Cow Creek drainage.  Part of this is still visible from the crater vent. 

Older lava flow fields surround Jordan Craters ranging 1.86 – 0.25 Ma.  Volumes are in the 0.8 – 1.0 km3 range.  The three older basalt fields connected to Jordan Craters are all to the S.  They all erupted from a single vent and all erupted around the same amount of basalt.  The oldest of these is immediately S of Jordan Craters.  It was active 250 ka, erupting 0.95 km3 of basalt from Clarks Butte that covered 202 km2.  Next vent was West Crater, on the SW corner of the older flow field.  It was active 150 ka, erupting 0.8 km3 of basalt that covered 29 km2.  The most recent of these fields erupted from Lava Butte, on the SE part of the Clarks Butte field.  It erupted 1.0 km3 of basalt 60 ka that covered 155 km2. 

The youngest dated flow is a basalt that flowed 16 km SE from Coffeepot Crater, filling stream valleys that were part of Cow Creek drainage.  This flow covers the Leslie Gulch Tuff to the W and older basalts N, E and S.  The final major flow extends S and E.  Its far corner extends into Cow Creek drainages.  Maximum flow thickness near a small collapse pit at Coffeepot Crater is 23 m.  Flow volume is estimated at 1.6 km3.  The lava was hot, very liquid, with a smooth pahoehoe surface.  There are gas release features including lava blisters and tumuli on the crust.  Flow formations include pressure ridges, squeeze ups and kipuka.  There are multiple collapse pits and sags, lava channels and tubes.  The network of lava tubes includes feeders and main tubes.  The larger tubes tend to meander.  Large tubes have collapse pits, and sagging roofs in places.  Some tubes are stacked, with false floors on the floor of the upper tubes. 

Age of the most recent flow is generally cited at 3,200 years.  A charred twig sampled during lake sediment coring in 1986 provides the date.  It is thought to mark the time that lava dammed the basin, though relationship between the lava flow, damming, and charring is not known.  Charcoal may predate the lake sediment by an unknown amount.  Lava flow features are well preserved and there is a near complete lack of soils and vegetation. 

Natives may have witnessed the main Jordan Craters eruption.  There is a petroglyph site overlooking the flow field.  Lava erupted into important hunting and gathering grounds.  More recent activity from the field was recorded by Bannock – Northern Paiute in the last few hundred years.  They passed stories of fire and smoke coming out of the ground to Euro American explorers and settlers in the 1800s.  There is no lichen in a 0.06 km2 portion of the field, which suggests minor eruptive activity a century or so ago. 

The 2018 update to the USGS national volcanic threat assessment lists Jordan Craters as 148/161 volcanoes in the US, color coded blue, very low threat, with an overall threat score of 4/263. 

Coffeepot Crater

The most recent eruption probably began along a fissure extending a couple kilometers along a SW-NE line.  As the eruption progressed, activity at the smaller spatter cones along the fissure ended and Coffeepot Crater became the dominant vent.  There is a line of spatter cones forming a ridge extending SW from the main crater.  This ridge extends another 0.8 km W forming three small, low-profile cones.  Alignment is likely due to underlying fracture / line of weakness.  Most of the spatter cones are intact.  The closest cone is part of the W crater wall of Coffeepot Crater. 

Coffeepot Crater at the NW edge of the field is the source for much of the basalt found to the SE.  Mildly explosive eruptions from Coffeepot Crater constructed a cone with overlapping lobes of scoria.  Eruptions transitioned between cinder, spatter and lava flows.  It is 80 m deep, 230 x 170 m, elongated E-W, constructed by interbedded cinder, spatter and lava beds individually 0.5 – 10 m thick.  The underlying Leslie Gulch Tuff is covered by a thin soil layer, perhaps 1 m thick.  Debris from the crater walls covers 50% of the floor.  Spatter makes up most of the crater walls.  The crater occasionally filled with lava which would then flow out though a complex network of tubes and channels.  Many of them are still visible. 

During the eruption, the cone held a lava pool that occasionally broke though the confining walls to raft chunks of the NW and SE flanks of the cone away.  The lava flows also created an extensive lava tube system.  As pressure decreased, lava pooled in the vent.  Variations in the pressure changed the level of the lake, pushing thin flows from the vent rebuilding the N and E walls of the crater, eventually building a splash rim.  Pooled lava degassed with small eruptions and fountaining.  This produced most of the cinders covering the vent area.

The lava lake eventually crusted over.  Magma withdrew, warping the crust downward, leaving vertical grooves on the crater wall.  After volcanism stopped, material continues to slump from the crater walls into the crater, burying the vent under its own debris. 

Tectonics

Given the proximity of Jordan Craters to the Snake River Plain, Columbia River Basalts, Yellowstone plume, and the Basin and Range Province, tectonics of the region are complex.  Central to this activity is the High lava Plains volcanic province and the Yellowstone hotspot.  Tectonic movement of the North American Plate is around 4.6 cm/yr SW.  This gives the Yellowstone hotspot an apparent movement to the NE, with the youngest set of calderas in Yellowstone over the last 2 Ma. 

The Columbia River Basalts erupted 17 – 6 Ma, covering 164,000 km2 of mostly E Washington State and Oregon with 174,300 km3 of basalt.  It is defined as a large igneous province (LIP).  Eruptions were most vigorous 17 – 14 Ma. 

Action of the Yellowstone hotspot 17 Ma – present is still in discussion, though we know its general motion over the last 10 Ma up the E arm of the Snake River Plain, where it formed multiple calderas and erupted massive rhyolite ignimbrites.  These eruptions were typically followed by subsequent basalt eruptions, some of them quite large.  What we do not know for certain is the connection between the source for the Columbia River Basalts and the Yellowstone hotspot.  Several theories have been proposed linking hotspot motion to post-caldera activity in the region.  We will end with what may be the most viable of them.

The other tectonic driver here is the migration / penetration of the Basin and Range Province, essentially a growing extensional regime in W North America into W Oregon from the S and E.  The High Lava Plains are located between all three major volcanic features. 

The High Lava Plains (HLP) are a volcanic province in east central Oregon stretching 275 km E-W and 85 km N-S.  Volcanic rocks exposed in the field range from 16 – 12 Ma – recent basalts and cinder cones.  Older volcanism erupted rhyolites in ash flows and domes.  Younger eruptions produced basalts.  

Rhyolites are progressively younger toward the W, ranging from around 10 Ma in the E to less than 1 Ma in the W.  This sort of westward propagating silicic volcanism also takes place in the northernmost 100 km of the Basin and Range Province, which is penetrating the HLP from the S and E.

HLP is a bimodial volcanic province, erupting either rhyolites or basalts, with very little in between.  Rhyolites are systematically younger as we go W, opposite that of Yellowstone hotspot eruptions which are younger toward the NE.  These rhyolites were erupted in 3 major ashflow tuffs and over 60 domes and tuffs and extend 70 km S into the intruding Basin and Range Province.  Basalt ages are far more scattered and represent a more complex source.

One of the best suggested models by BT Jordan in Mantle Plumes, Jul 2006, for this activity is the spreading of the Yellowstone Plume head over time.  The plume hits the overlying crust.  There is a craton to the W, and the plume head spreads out, putting more and hotter material to the E.  Over time, the plume drives a circulation of magma fueling future volcanic activity.  Note that this model can also explain the location and eruption of the Columbia River Basalts. 

Conclusions

Jordan Craters is one of the youngest basalt fields in E Oregon.  Its magma source is likely the Yellowstone hotspot, so there ought to be magma available for future eruptions in the region.  Most recent eruption may be no more than a century ago.  The surrounding area is unpopulated, and the field is not individually monitored, though there is regional seismic coverage.  USGS lists Jordan Craters as a very low threat system. 

Additional information

Notes on the geology of southwestern Idaho and southeastern Oregon, IC Russell, USGS, 1908

Jordan Craters volcanic Field, N Pollock, Department of Geosciences, Bosie State University, Jul 2018

Mineral resources of the Jordan Craters wilderness study area, Malheur County, Oregon, Calzia, et al, USGS Open-File Report 88-572, 1988

Identifying lava-water interactions with VNIR:  a preliminary study at Jordan Craters, Oregon, Reeder, et al, Dec 2019

Crystallinity and albedo:  in-situ VNIR analysis of glassy lava flow surfaces at Jordan Craters, OR, A Reeder, Dec 2020

The geology of Jordan Craters, Malheur County, Oregon. Otto & Hutchison, 1977

The identification of lava/water interaction through VNIR analysis:  a trial study at Jordan Craters, Oregon, Reeder, et al, Mar 2019

Analytical results and sample locality map of rock samples from the Jordan Craters Wilderness Study Area (OR-003-128), Malheur County, Oregon, USGS Open-File Report 90-449, 1990

Basaltic volcanism and tectonics of the High Lava Plains, southeastern Oregon, BT Jordan, PhD Dissertation, Jun 2001

2018 update to the US Geological Survey national volcanic threat assessment, Scientific Investigations Report 2018-5140, USGS

Diamond Craters, D Sherrod, Oregon Encyclopedia

The Ore Bin, Aug 1977, Volume 39, No 8, State of Oregon, Department of Geology and Mineral Resources

Open-file report 0-92-09, Preliminary geologic map of the Jordan Craters south quadrangle, Malheur County, Ferns & MacLeod, 1992

The Oregon High Lava Plains:  proof against a plume origin for Yellowstone?, BT Jordan, Mantle Plumes, Jul 2006

Tectonic and magmatic evolution of the Snake River Plain volcanic province, Editors Bonnichsen, et al, Idaho Geological Survey, University of Idaho, Bulletin 30, 2002

Bimodal volcanism of the High Lava Plains and northwestern Basin and Range of Oregon:  distribution and tectonic implications of age-progressive rhyolites, Ford, et al, May 2013

Geochronology of age-progressive volcanism of the Oregon High Lava Plains:  implications for the plume interpretation of Yellowstone, Jordan, et al, Oct 2004

Basaltic volcanism of the central and western Snake River Plain:  a guide to field relations between Twin Falls and Mountain Home, Idaho, Oct 2005

Origin and stratigraphy of phreatomagmatic deposits at the Pleistocene Sinker Butte volcano, western Snake River Plain, Idaho, B Brand, 2007

Geologic and tectonic history of the western Snake River Plain, Idaho and Oregon, Wood & Clemens, 2002