Australia 2 – Volcanic Activity in Northern and Central Queensland

Volcanic fields and provinces in Queensland. Image screen capture courtesy Jones Thesis 2018, Evolution and migration of Cenozoic Australia.

 

I originally intended to cover all volcanic fields and provinces I could find in Queensland.  Turns out there were a lot of them, so many that the post grew too large.  Will limit this post to northern and central Queensland, and bundle southern Queensland with New South Wales in Part 3, the next post.  With that being said, let’s take a look at Queensland.

Queensland is an Australian state in the northeast quadrant of the continent.  Its area is roughly a sixth of the contiguous continent.  It is bordered by the Coral Sea to the north and the Pacific Ocean to the east.  Neighboring states are New South Wales to the south and the Northern Territory to the west.  Population is in the neighborhood of five million, concentrated mostly along the coast with the heaviest concentration to the southeast.  The state capital is Brisbane.

Aboriginal settlement of this part of Australia took place at least 50,000 years ago, with the first people crossing via boat or land bridge.  The last ice age turned what was largely a tropical region into a more arid one, making food increasingly scarce.  Warming following the end of the last ice age brought high rainfall along eastern coast.  This part of Australia also regularly sees cyclones hit from the east.

Volcanic neck / plug Mount Coonowrin unofficially goes by the name Crookneck. Photo courtesy Queensland.com. https://www.queensland.com/

 

Europeans showed up in 1606, bringing along with them a smallpox epidemic like they did in the New World.  There was a war between Aborigines and European settlers in the mid-19^th century.  Australia was federated in 1901 and former colonies established as states.  The colonies and the newly formed nation also settled their differences with the Aboriginal peoples.

Climate inland to the west is generally dry and hot humid.  There is a monsoon wet season in the far north and warm, wet temperate conditions along the coast.

Economic drivers are primarily farming, ranching, mining and tourism.  Queensland has significant coal and bauxite deposits.  It also has some oil shale and natural gas.  Gold mining was a significant industry in the mid-19^th century.

Plume model of northern Queensland volcanic activity. Cross section is generally north to south with north being at the left of the drawing. Volcanic provinces / basalt field’s names are depicted at the top of the drawing starting with Silver Plains and ending with Sturgeon. Screen capture from Sutherland, 1998. https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/97JB03578

 

Volcanic and Tectonic Overview

Along with everything else, Queensland has volcanoes, some quite old, some among the youngest in the entire country.  Some of the younger ones erupted massive basalt lava flows nearly 200 km3 in volume over the course of a few million years.

Volcanic activity takes place in the Eastern Australian Volcanic Zone, which is mostly parallel with the eastern Australian coast line.  Activity in the Queensland portion of the zone appears to be related to continental passage over an underlying low velocity zone that injects blobs of magma into the transiting continent.  Those magma fingers eventually find their way to the surface through weak spots in the passing plate.  Typical active eruptive lifetime is on the order of 3 million years.  One author believes that Queensland is in the early stages of its passage over a low velocity zone that lies to the north, meaning there will be a good supply of eruptible magma for the next several million years.

The best source for researching past volcanic activity in Australia is a book entitled Intraplate Volcanism: In Eastern Australia and New Zealand, published in 1989 compiled by RW Johnson.  Some excerpts from the 408 pp book are available in Google Books preview.  The used book itself is available from Amazon for a mere $842 US for hardcover or $41 US paperback.  Well worth your time to read.  No complete pdf of this exists that I was able to find.

Bats leaving Undara lava tube at night. Image courtesy Tropical north Queensland. https://www.tropicalnorthqueensland.org.au/listing/product/undara-experience/

 

Lava field activity in Queensland to the north is sporadic, voluminous (nearly 200 km3 for the largest field / province), and relatively recent (as recent as 13,000 years old).  A series of articles a decade ago quoted Professor Bernie Joyce saying chances of future eruptions in Australia were more a matter of when rather than if.  Having recent volcanic eruptions, Queensland was listed as one of the possible locations for the future activity.

Lava inflation pit in Toomba basalt flow. Image courtesy Peter Whitehead, 2010. http://www.vulcanospeleology.org/sym14/papers/Whitehead-McBride.pdf

 

Volcanic activity in north Queensland has been going on since at least 9 Ma with no noticeable gaps in activity, though activity does date back tens of millions of years before then.  The most volcanically active period has been over the last 2 Ma, with 91 dated eruptions.  This averages one eruption every 22,000 years.  The actual eruption rate is more frequent as there are many undated eruptions.  Many of the youngest volcanoes have not been dated or analyzed.  One example is the Atherton Volcanic Province that has at least 29 undated volcanoes that are likely less than 1 Ma and in some cases much less than 50,000 years old.

A more recently calculated eruption frequency may be in the vicinity of one eruption every 10,000 years as the numbers of eruptions dated and mapped have not captured all the activity.  This in turn suggests that northern Queensland has potential for future activity.

Comparison of north Queensland lava fields. Screen capture from Sutherland, 1998. https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/97JB03578

 

Volcanic Fields and Provinces

Queensland hosts at least nine central volcanoes and 14 lava fields.  Its volcanic centers are a combination of very young and relatively older central volcano dominated fields.

There are 11 basaltic volcanic provinces north and inland from Townsville.  They range in age from 44 Ma to recent.  Younger provinces are lava field type with hundreds of monogenetic volcanic centers.  Each center is oval shaped, up to 80 km across.  Two much older centers are isolated intrusive centers with no associated lavas.  Four provinces contain 20 lava flows longer than 50 km.  Three of these have very long lava flows (Undara, Kinrara in the McBride province and Toomba in the Nulla province).  These long flow provinces are relatively recent.

Volcanic features in Queensland. Image courtesy Oregon State. http://volcano.oregonstate.edu/oldroot/volcanoes/volc_images/australia/volc_australia.html

Recent lava field provinces active within the last 8 Ma include:  Piebald, Cooktown, Atherton (most recently active in Queensland) , McBride, Walaroo, Mt Fox, Chudleigh, Broken River, Mingela, Nulla, and Sturgeon.

Central volcano dominated fields are to the south of the previously listed lava field provinces were active 32 – 23 Ma.  These include Mount Dukes, 32 Ma, Hillsborough, 32 Ma, Nebo, 28 Ma, Peak Range, 30 Ma, Hoy, Springsure, 27 Ma, Buckland, Mitchell, Bauhinia and Monto.

The following is a more detailed look at volcanic features in Queensland.

 

Torres Strait islands (Maer volcanic province). Image courtesy Tores Straits tourist information. http://www.riverbendnelligen.com/tisummary.html

 

Maer

The Maer volcanic province (also known as the Maer Volcanics) are eight small islands in the NW part of the Torres Strait dated 3 – 1 Ma.  The cover a total area of perhaps 140 km2.  Three volcanic centers are recognized with a total volume around 1 km3.  Some of the smaller islands are only mafic lava flows.  Others are pyroclastic with some limestone fragments.  All are covered with dense tropical forests or grasses.  Eruptions at each center began below sea level.  Some of the islands show remains of base-surge eruptions.  It is the northernmost province of the East Australian Volcanic Belt.

Eroded volcanic vents north of Cooktown. Image courtesy greadbarrierreef.org http://www.greatbarrierreef.org/destinations/cooktown/

 

Silver Plains, Piebald and Cooktown Volcanic Provinces

The Piebald province volcano is located north of Cooktown in North Queensland.  There are 14 identified vents.  Most recent eruption was 1.2 Ma for Piebald and 1.6 Ma for neighboring Bald Hills.  There are residual basaltic hills that may represent small shield volcano remnants.

McLean volcano (also known as the McLean volcanic province) is an extinct volcano SW of Cooktown.  It has 18 volcanic vents, scoria cones and composite cones.  Older eroded volcanoes are located nearby.  The region is larger than Piebald.  Age determination for the older volcanoes date 6.3 – 3.1 Ma.  Undated younger cones and lavas are thought to be less than 1.0 Ma.

The majority of younger vents are scoria cones.  There are several broader volcanoes thought to be composites.  Much older basaltic rocks east and SE are lava cones.  There is a possible maar structure identified.  Most of the volcanic rocks from McLean are nephenlinites, leucites, basalts and alkaline basalts.

Additional volcanoes as part of these provinces are variously referred to as Silver Plains and Cooktown.

Seven Sisters in Atherton volcanic province / field. Image courtesy https://www.yungaburra.com/local-info/photo-gallery/sevensisters_s/

 

Atherton Volcanic field

This volcanic province is primarily a scoria / shield volcanic field.  One of the youngest fields on the continent.  Contains more than 50 eruptive centers covering 1,800 km2.  Formations include shield volcanoes, lava flows, cinder cones, maars and at least one diatreme.  The region has heavy rainfall and in turn deep red soils.  It is the only area in northern Queensland that has maars, likely due to higher rainfall and presence of ground water.

The field occupies what is called the Atherton Tablelands, uplifted portion of the Great Dividing Range along eastern Australia.  What formed this range is still disputed, with suggestions it was related to rifting events that opened the Tasman and Coral Seas 84 – 53 Ma.  The other theory is that the range was formed by mantle plume low velocity zone magmas rising upward.

Map of Atherton volcanic province. Image courtesy Millaa Millaa. http://www.millaamillaa.com/volcanic.htm

 

Volcanic activity began 7.1 Ma.  There were peaks 3.5 – 3 Ma and 2 – 1 Ma.  Activity changed over time, with voluminous lava flows that built large shield volcanoes changing to less voluminous lavas and pyroclastics that built numerous cinder cones over the last Ma.  Phreatomagmatic, maar forming eruptions were the most recent eruptions.  Maars are generally young, in the 200,000 – 10,000 year range.  The source region for the province is thought to be 80 km in diameter.

The province has broad lava plains on the tableland, with erosion more prominent in the south (newer volcanics to the north).  Volcanoes that produced the lava flows date 1.8 – 1.2 Ma.  There were at least two complete gorge fillings in the Johnstone River drainage with lavas up to 300 m thick.  A northern tributary of the Wild River has a 7.1 Ma lava flow over 100 m thick.

The province also contains offshore volcanic islands.  Stevens Island in the South Barnard Islands is an offshore volcano with an eroded pyroclastic cone.  Layering of the rocks that build the cone indicates base surges.

Mount Hypipamee Crater from the surface. Entire diameter of diatreme is visible. Plant growth on the surface of the water turns it green. Image courtesy Trover.com. https://www.trover.com/d/eUmh-mt-hypipamee-crater-upper-barron-australia

 

Mount Hypipamee Crater is a diatreme.  It was originally called “the crater” or the “Herberton Crater” and later renamed to the Aboriginal name Mount Hypipamee in the 1930s.  The crater is 61 m in diameter and at least 82 m deep.  Water level is 58 m below the surrounding surface.  It hosts a lake covered with duckweed.  Locals long thought it was connected via underground waterways to other local lakes.  Such connections do not exist.  The diatreme is surrounded by a National Park.

Flow outlines for three long basalt lava flows. Screen capture from Stephenson, et all, 1998. https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/98JB01670

 

Long Flow Volcanic Provinces

The next four volcanic provinces to the south, McBride, Chudleigh, Sturgeon and Nulla have significant lava field coverage.  The smallest, Chudleigh, dates 8.0 – 0.2 Ma.  It erupted 50 km3, covered 2,000 km2 from 46 eruptive centers.  The largest, Nulla, dates 5.2 Ma – 13,000 years ago.  It erupted 187 km3, covering 7,500 km2 from 46 eruptive centers.  These four provinces contain 20 lava flows longer than 50 km.

Of particular interest is the notion that this region has seen massive volcanic eruptions, similar lavas, and short lived eruptions of significant volumes, with millions of years between eruptive episodes.  As such, this region is not likely to be extinct just yet.

Summary of four basalt provinces with long lava flows. Screen capture from Stepehnson, et all, 1998. https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/98JB01670

 

Comparison of three longest basalt lava flows. Screen capture from Stephenson, et all, 1998. https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/98JB01670

 

Effusion rates are thought to be similar to what we are currently seeing at Kilauea.  Lava tubes and caves are common in these long lava flows, with some tubes over 30 km from the source.  The flows do not require high effusion rates if the flows are tube-fed, which it appears these all were.  The flows are working relatively low slope terrain.  Flow surfaces are typically pahoehoe and ‘a’a.  Toomba and Undara low aspect shields show close similarities to similar postglacial shields in Iceland.  Kinrara is much steeper.  Undara and Toomba lava fields may have developed from sustained eruptions with relatively low effusion rates.  Kinrara likely had a higher effusion rate.

Toomba and Undara volcanoes in McBride volcanic province. Image courtesy Cohen, et all. https://www.sciencedirect.com/science/article/pii/S1871101416300826

 

McBride Basalt Province

The McBride Province is one of nine lava field provinces in north Queensland.  These are closely aligned with the Great Divide, which suggests a relationship between uplift and volcanism.  Flow fields of these provinces indicate the Divide was in place first, though there appears to be some post-eruption uplift.

McBride covers 5,500 km2 with 164 eruptive centers and is located on a preexisting regional dome similar to the Chudleigh, Sturgeon and Nulla provinces.  Oldest eruptions began 8 Ma, with the bulk of eruptions over the last 2.7 Ma.  The youngest is Kinrara, 52,000 – 18,000 years old.  The older set of basalts date 7.8 – 7.3 Ma.  There was a break until the more recent and voluminous eruptions began 2.7 Ma.

There are two shield volcanoes, Racecourse Knob and Mount Munana.  Mount Lang and Chubber’s Hill are composite cones.

Schematic of Undara basalts. Image courtesy Peter Whitehead, 2010. http://www.vulcanospeleology.org/sym14/papers/Whitehead-McBride.pdf

 

Undara lava flows cover 1,510 km2.  Lava caves exist up to 30 km from the crater.  The cone rises only 10 – 40 m above the surrounding flow field.  There is no evidence of pyroclastic material.  The summit crater is a third of a kilometer across and has at least a single bench that indicates it had a lava lake.  Lavas overflowed at several points around the rim of the crater and for the most part flowed north, a shorter distance east and west.  Undara is only the most recent manifestation of activity at this location.  The Undara lava flow is the longest recorded lava flow in Australia and one of the longest on the planet, similar in length to the Pampas Onduladas flor in Argentina.

Kinrara volcano, McBride volcanic field. Image courtesy Australia for Everyone. http://www.australiaforeveryone.com.au/volcanoes.html

 

The Kinrara volcano is a well preserved 400 m tall volcanic cone with a steep crater.  It is the youngest crater in McBride.  Parts of the cone are pyroclastic with lava fountains and spatter constructs.  There is a second low spatter cone a kilometer north of the main crater.  The central crater has a solidified lava lake and terraces that indicate former lake levels.  There are a complex system of lava tubes within 6 km of the vent.

The Gugu Badhun Aboriginal people have stories about the earth being on fire along the rivers.  A second legend tells of a time when a witchdoctor made a pit in the ground, put a lot of dust in the air, and people got lost in the dusty air and died.  This is thought to document eruptions from Kinrara, though these legends are remarkably long lived if accurate.

The Murronga flow is in the south-central McBride Province.  It came from Mount Tabletop, a group of three high symmetrical pyroclastic cones with summit craters.  The flow extends 40 km and covers 235 km2 and appears to have been constructed of several flow fronts and pulses of lava.

Mount Fox cinder cone. Image courtesy Hidden Valley cabins. http://hiddenvalleycabins.com.au/tours-activities/activities/

 

Mount Fox is an old cinder cone, 50 km west of Ingham.  It has a shallow crater and lava flow.  It is built on a 23.6 Ma basaltic lava flow.  Ages of this cone vary wildly, with the best estimates between 200,000 – 100,000 years with an error of 50,000 years.  One paper listed it as 560,000 years old.

The Wallaroo Basalt Province is a 130 km2 outlier located 16 km east of the NE corner of McBride.  There is no recent activity and basalts were erupted in roughly the same times as other McBride basalts from four known vents.  The only dated lavas date 6.6 Ma.

Undara lava tube. Image courtesy Australian Traveller. https://www.australiantraveller.com/qld/tropical-north/cairns/100-things-to-do-before-you-die-089-ooze-along-undaras-lava-tube/

 

Chudleigh

Chudleigh Volcanic Province has numerous mesa-basalt remnants between the continuous basalt plateau and plains of the Chudleigh and Nulla provinces.  These basalts are thought to be the remnants of continuous sheet basalts bridging the provinces.  These basalts are dated 8.9 – 7.8 Ma, older than the ages of neighboring provinces.  There are at least four eruptive provinces recognized among the mesas.

Clarke Hills is a sub-province of somewhat older volcanic activity, though younger volcanoes and valley lavas are dated within it, 4.5 – 0.7 Ma.  Total coverage by lava flows is around 2,000 km2.  There is a 100 km long lava flow down a river bed from Barker’s Crater.  Total of 46 volcanic structures have been identified.  These include composite cones, pyroclastic cones, lava shields and wide lava flows over the plains.  Most recent volcanic activity is 250,000 years old.

Chudleigh has lava tubes present in the lava flows.  One of these, Barker’s Cave is 300 m long, 20 m wide and 7 m high.

Exposed Toomba flow at Basalt Corner where a river has undercut the flow. Image courtesy Oregon State. http://volcano.oregonstate.edu/vwdocs/volc_images/australia/toomba/toomba.html

Sturgeon

The Sturgeon Volcanic Province is part of a broad topographic dome thought to be a Miocene uplift.  Volcanism began after the uplift.  Lava flows followed newly eroded valleys in the uplifted dome.

The area covers 75 km2 and has 46 volcanic centers.  Volcanic activity started 5.5 Ma and continued sporadically until 0.9 Ma.  The youngest Sturgeon flow is dated 0.92 Ma and stretches at least 120 km from its source.  Lava flow sources have been confirmed as old as 5.5 Ma.  These built high mesas.  A 110 km lava flow is a series of well-defined mesas with ages in the 3.3 Ma range.  The oldest activity is difficult to pin down as it has either been eroded or covered with younger lava flows.  Lavas here are similar to those erupted from neighboring Chudleigh and McBride provinces.

Nulla

The Nulla volcanic province covers 7,500 km2 from 46 known vents.  These produced voluminous lava flows into neighboring valleys.  These lava flows started 5.2 Ma and were nearly continuous until the most recent eruption from Toomba volcano some 13,000 years ago.

Toomba is well preserved with fissure vents and minor pyroclastic cones.  It is a low-aspect composite structure with multiple effusive centers, possibly fissure vents trending north.  The cone is 4 -5 km across and 100 m high.  There are several small low angle pyroclastic cones.  Lavas are likewise basalts with pahoehoe and ‘a’a surfaces.  There are four successive flow types from Toomba with the later flows likely cooler and more viscous.

Cape Hillsborough volcanics. Most northerly portion of recently identified Cosgrove volcanic chain. Image courtesy http://www.abc.net.au/news/science/2015-09-15/worlds-longest-continental-volcanic-chain-in-australia/6769360

 

Hillsborough

The Hillsborough province dates 34 – 31 Ma.  It is along the eastern shore and exposed along a 5 km coastal exposure.  Volcanic rocks appear to be the residual flank of a pair of central volcanoes.  Several small pyroclastic and lava plugs are visible.  The rocks are rhyolites and pyroclastic deposits totaling over 300 m thick.  Individual flows are up to 30 m thick.  Basalt lavas and pyroclastics are found in the lower part of the pile.  The longest continental chain of volcanoes mentioned in the Introduction post begins a Cape Hillsborough.

Nebo

Activity in the Nebo province has been very long lived, ranging as far back as a 55 Ma basalt.  The most recent exposed volcanic rocks are a flank vent on Mount St. Martin, dated at 3 Ma.  This is volcanic breccia covered by a flow remains.  The province is dominated by central volcano eruptive sequences.  Some of the most of the nepheline rocks appear to be mantle-derived younger magmas unrelated to the central volcano suite.  There was also minor recent alkaline volcanism that formed Mount St. Martin.

Well eroded volcanic remains in surrounding Mount Nebo. Image courtesy Aussie Bushwalking, Morelia Track, Manorina National Park. https://www.aussiebushwalking.com/qld/brisbane-forest-park-d-aguilar-national-park/manorina-national-park/morelia-track

 

Mingela

The Mingela volcanic province is much older and more eroded.  It has 22 known plugs and several dikes concentrated in a 50 km long belt in the Arthur Peak and Mingela regions.  There are no lava flows evident.  The most prominent hill is the youngest at 35 – 31 Ma.  Remaining plugs date 44 – 41 Ma.

Other Central Queensland Volcanics

There are other basaltic lava flows 50 km south near Ruxton.  The youngest of these is 26 Ma.  A neighboring isolated basaltic lava flow field dates flows as 27 and 19 Ma.  There is an eroded hawaiite plug 29 Ma farther west beyond the McBride volcanic province.

Basalts in Paynes Lagoon and Valpre are small, covering only 10 km2.

There are six eroded plugs in the Torrens Creek and Pentland district.  These are up to 1.5 km in diameter and date 27 – 25 Ma.

Central Queensland

Wolfgang Peak, Peak Range National Park. Image courtesy Explore Australia. http://www.exploreaustralia.net.au/Queensland/The-Mid-Tropics/Clermont

 

Peak Range

The Peak Range volcanics are a suite of alkaline trachytic and rhyolitic domes, plugs, dikes, other intrusions and minor lava flows.  It appears that some much older lava flows and associated vents are referred to as the Clermont South volcanic province likely named after geographic mapping area – Clermont Sheet.   These date back as far as the Triassic.

Peak Range is aligned generally along a NW – SE 100 km long line and covers 2,500 km2.  The line is a major pre-Permian fault.  It is a chain of prominent hills surrounding by flat basaltic lava plains.  The primitive basalts filled erosion channels carved before the volcanic activity.  Pyroclastic deposits are rare, though this might be due to erosion.  Ridged peaks and mesas were built by up to 50 flows in a 300 m sequence.  The province is older than 27 – 25 Ma.  Earliest lavas date 40 – 34 Ma.  Vents are widely distributed.  There is an apparent southward movement of volcanic activity in the province over time.  Total erupted volume is estimated at 2,600 km3.  It is the largest central volcano in central Queensland, the second largest in Australia.

Peak Range National Park, Queensland. Image courtesy Jarrod Allison, Instagram / Pintrest. https://www.pinterest.co.uk/pin/542261611378663228/

 

Basalts were fed by fissures, small vents, dikes, sills and plugs.  Most of the dikes are less than 3 m wide.  Some are 1.5 km long.  Erosion exposed plugged throats of vents that now show as small, symmetrical cones less than 100 m high.  There are eroded concentric ring remains, each 1.5 km in diameter.  Their origin is unknown, perhaps eroded remains of shield volcanoes.

There are at least 16 volcanic domes at the southern end of the Peak Range.  They are various flavors of trachytes.  There are at least 15 plugs at the northern and 7 at the southern end of the range.  These domes are rhyolites.  Columnar jointing is common in most of the plugs.  Rhyolite dikes occur mostly in the northern part of the range while trachyte dikes occur throughout the region.  Flows of rhyolites and trachytes are rare in comparison with basalt lavas.  There are small thick trachyte flows in the northern part of the range.

Volcanic activity appears to have started with massive basalt lava flow sheets and changed to trachytes and rhyolites toward the end of activity as the magmas evolved before erupting.

 

Hoy

Hoy volcanic province is to the west of the Peak Range and Springsure provinces.  Policeman’s Knob is an isolated volcanic plug that has columnar basalts.  It is poorly dated 67 – 53 Ma.

Virgin Rock, Springsure volcanic province. Image courtesy Nuggets Outback Photography. https://www.nuggetphotograph.com/

 

Springsure

Springsure is bi-modal composite volcano with a diameter of 100 km.  It erupted 1,460 km3 covering some 5,400 km2.  Extensive erosion removed much of the original shield and exposed vents, pipes, plugs and dikes.  Mount Catherine is one exposed section of flows.  It has 11 mapped flows on the southern edge of the greater volcano.  Flows are primarily alkaline basalts and date 28 – 27 Ma.  It is similar in structure and age to the Peak Range volcanics.  Eruptive sequence once again appears to start with extensive basalts, followed by pyroclastics, and trachytes and basalts to finish.

Buckland and Mitchell

The Buckland volcanic province covers some 15,000 km2 in two parts.  The first is a large eroded shield to the east covering 6,000 km2.  The western portion is a sparse scattering of intrusive and flow remnants.  The shield is eroded by deep gorges filled by basalts.  Primary eruptive products are a variety of basalts.  One sequence is up to 300 thick.  There are remnants of 60 intrusive bodies and as many flow remnants.  Most intrusions are plugs, dikes and close clusters of alkali basalts.  These date 25 Ma.  Buckland is estimated to have erupted 860 km3 over its time of activity.

Buckland is a relatively old central volcano.  It originally covered some 6,000 km2.  It was built in two phases separated by 2.5 Ma, 30 Ma and 27 Ma.

Mitchell is a series of theolitic basalts that fill old river beds.  One of the flows is over 120 km long.  Thicknesses are typically 30 – 80 m.  Basalts in both portions of the Mitchell province date 24 – 21 Ma.  Its close proximity to Buckland and the correspondence with younger volcanism around Buckland implies Buckland and Mitchell have a closely related magma source.

Salvator Rosa national Park, Bauhinia. Image courtesy Queensland Places.com. http://queenslandplaces.com.au/exhibit/slide/lc229

 

Bauhinia

Bauhinia basalts are scattered outcrops over a 500 km2 area.  There are thick basalt caps in the Expedition range in the western portion of the province forming a 310 m thick sequence with seven flows stacked on one another.  These lava flows date 27 – 22 Ma.  It is a lava field located in the Bowen Basin.  It shares a boundary with the Springsure volcano.  Like other lava flow fields, lavas filed erosion channels.  Lavas date 28 – 22 Ma.  Given the close proximity between provinces and their overlap in age, it is possible that they have the same magma source.

 

Monto

There are basalt outcrops over 1,000 km2 in the Monto and Bundubbera areas.  These lava flows are on either side by a divide in the Dawes Range.  The oldest dated plug is 70 Ma.  There is a dolerite dated at 47 Ma.  The majority of the activity appears to have taken place 28 – 21 Ma.  This field is 400 km east of Bauhinia.

Undara volcano from the air. Note small lake in the center of the crater. Image courtesy Queensland Tourism & Events. https://www.queensland.com/attraction/undara-volcanic-national-park

 

Conclusions

The next post will cover volcanoes and volcanic provinces in southern Queensland and New South Wales.  These are generally a combination of heavily eroded central volcanoes and basalt lava fields.

Volcanic activity in Queensland generally supports the theory of upwelling mantle magma diapirs / magma fingers working their way through weak spots in the overlying continent.

I have not seen this formally suggested in any paper I ran across during construction of this piece, but to me, volcanic activity in Queensland looks like it has proceeded as follows:  Initial activity is generally massive basalt lava flows followed by construction of central volcanoes as the magma evolves prior to reaching the surface.  More recent volcanic provinces like Atherton, McBride, Chudleigh and Sturgeon look like they are still in the lava flow stage.  Much older regions like Peak Range, Springsure and Buckland are at the point in their evolution where the central volcanoes are the only identifiable activity remaining after tens of millions of years of erosion.  Total lifetime of activity is in the vicinity of 3 Ma, though there are a few areas that have been active far longer than that.  Note also that 3 Ma is about the active time of a typical Hawaiian volcanic vent.

As usual, not in any way an expert, but a hobbyist.

St. Peter, Springsure, Queensland. Part of the Minerva Hills formation. Image courtesy Nugget, ABC Open. https://open.abc.net.au/explore/174500

 

Additional Information

https://www.amazon.com/Intraplate-Volcanism-Eastern-Australia-Zealand/dp/0521123224

http://volcano.oregonstate.edu/oldroot/volcanoes/volc_images/australia/volc_australia.html

https://www.volcanocafe.org/australian-volcanoes/

https://www.wired.com/2009/09/is-australia-overdue-for-a-volcanic-eruption/

https://www.sciencedaily.com/releases/2011/07/110705104205.htm

http://austhrutime.com/australian_volcanoes.htm

https://books.google.com/books?id=Ch_1JlLkKE0C&pg=PA204&lpg=PA204&dq=australian+volcanic+fields&source=bl&ots=hLz385bdBK&sig=QVlHUBULlVNvfGqUhJleprf5Qzo&hl=en&sa=X&ved=0ahUKEwiArvzO_6bcAhUJ-58KHY8JCbQ4ChDoAQhDMAk#v=onepage&q=australian%20volcanic%20fields&f=false

http://www.australiangeographic.com.au/travel/destinations/2017/02/tropical-north-queensland-undara-lava-tubes

http://www.gold-coast-australia-holidays.com/support-files/tweed_volcano.pdf

http://www.millaamillaa.com/volcanic.htm

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/98JB01670

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/97JB03578

http://www.vulcanospeleology.org/sym14/papers/Whitehead-McBride.pdf

http://www.tropicalnorthqueensland.org.au/listing/product/mt-hypipamee-crater-and-dinner-falls/

https://www.earthmagazine.org/article/travels-geology-northeastern-australias-atherton-tablelands-young-volcanoes-waterfalls-and

http://eprints.gla.ac.uk/134886/9/134886.pdf

https://d28rz98at9flks.cloudfront.net/181/Bull_071.pdf

https://d28rz98at9flks.cloudfront.net/100760/Rec2017_023.pdf

https://d28rz98at9flks.cloudfront.net/14981/Rep_066.pdf

Advertisement