Aerial view of Mount Morning from the northeast.
|Elevation||2,725 m (8,940 ft) |
|Prominence||1,515 m (4,970 ft) |
|Mountain type||Shield volcano|
|Volcanic belt||McMurdo Volcanic Group|
Mount Morning is a shield volcano at the foot of the Transantarctic Mountains in Victoria Land, Antarctica. It lies 100 kilometres (62 mi) from Ross Island. Mount Morning rises to an elevation of 2,723 metres (8,934 ft) and is almost entirely mantled with snow and ice. A 4.1 by 4.9 kilometres (2.5 mi × 3.0 mi) wide summit caldera lies at the top of the volcano and several ice-free ridges such as Hurricane Ridge and Riviera Ridge emanate from the summit. A number of parasitic vents mainly in the form of cinder cones dot the mountain.
The volcano was initially active during the Miocene and erupted in two separate stages with a hiatus in between. The older stage has a different chemical composition than the recent one and is heavily eroded by glaciers. The most recent parasitic vents were active about 20,000 years ago and the volcano could erupt again.
Geography and geomorphology
Mount Morning lies in Victoria Land, about 100 kilometres (62 mi) from Ross Island and at the foot of the Transantarctic Mountains. The Koettlitz Glacier runs along the northwestern foot of Mount Morning and separates it from the Royal Society Range 25 kilometres (16 mi) away.
The volcano rises to 2,723 metres (8,934 ft) above sea level and is capped by a 4.1 by 4.9 kilometres (2.5 mi × 3.0 mi) wide caldera. Mount Morning has been defined as a 30 by 36 kilometres (19 mi × 22 mi) large shield volcano that consists of a central volcano overlying an older volcanic complex. Fissure vents have produced at least 185 parasitic vents on the slopes of Mount Morning. They are cinder cones, fissure ridges, lava domes and volcanic necks, and their diameters range from a few metres to a few hundred metres. Many of the vents form alignments, some cone craters overlap or the vents themselves have linear shapes. These linear patterns defne northeast-southwest trends, with a minor northwest-southeast alignment. Lava flows emanate from cones and make up the present-day surface of the volcano.
Mount Morning is almost entirely covered with snow and ice except where it is ablated by southerly winds. Outcrops of volcanic rocks are found at the north-northeastern Riviera Ridge and northeastern Hurricane Ridge on the northern flank, Mason Spur on the southern flank and on Helms Bluff on the eastern flank. Gandalf Ridge is a promontory at the foot of Hurricane Ridge, and Pinnacle Valley is located on the Riviera Ridge. Dikes, lava domes, lava flows and pyroclastic deposits are found in outcrops. Mason Spur also contains breccias from pillow lavas, while Gandalf Ridge features a diamictite and a cross-cutting fault.
Owing to the lack of running water, the edifice is uneroded and parasitic vents have a young appearance. Glacial erosion has eroded some parts of the volcano, leaving volcanic necks in Pinnacle Valley, has etched glacial striations into exposed volcanic rocks and deposited glacial till. The Vereyken Glacier descends the northeastern slopes of Mount Morning between Hurricane Ridge and Riviera Ridge. Moraines occur on these two ridges and moraines dating to the Wisconsin glaciation have been reported. Glaciers descending from Mount Morning feed the Koettlitz Glacier. Several lakes are found on the volcano and at its foot, including Lake Morning at the end of the Riviera Ridge.
The West Antarctic Rift is a major geological feature in Antarctica and one of Earth's largest continental rifts. It is a region of active crustal extension and spreading, which may be ongoing today. Volcanic activity occurs at the rift and includes the McMurdo Volcanic Group, a 2,000 kilometres (1,200 mi) long chain of volcanoes in Victoria Land. This volcanic group has erupted alkaline lavas during the course of the Cenozoic. It is subdivided into three provinces, the Hallett, the Melbourne and the Erebus province; Mount Morning is the southernmost volcano of the Erebus province.
Basanite is the dominant rock of outcrops, with phonolite less common and picrobasalt and tephrite rare. Outcrops of older rocks include mugearite, rhyolite and trachyte. Textures range from porphyritic to seriate. Various phenocrysts are found within the volcanic rocks, including aegirine, augite, clinopyroxene, alkali feldspar, kaersutite, nepheline, olivine, plagioclase, quartz and sanidine. Aegirine, aenigmatite, amphibole, augite, clinopyroxene, alkali feldspar, glass, iron oxide-titanium oxide, nepheline, plagioclase and quartz make up the groundmass. The volcanic rocks contain xenoliths consisting of syenite and of rocks from older stages of Mount Morning activity. Spinel peridotite and less commonly clinopyroxenite, dunite, harzburgite, lherzolite, norite, pyroxenite and websterite have been reported as xenoliths.
The early volcanic rocks of Mount Morning are comparable to mildly alkaline rocks from Mount Melbourne, while the more alkaline late volcanic rocks resemble these from Mount Erebus. Basaltic rocks are concentrated on the lower slopes, while phonolite is mainly found in the upper sector of Mount Morning. The composition changes between the early and late volcanic activity of Mount Morning may be due to alteration in crustal magma processes.
Mount Morning has been active during the Miocene, Pliocene and Pleistocene. Argon-argon dating and potassium-argon dating have been used to infer the duration of volcanic activity at Mount Morning. Gandalf Ridge has yielded ages of 18.7±0.3-15.5±0.5 million years, Pinnacle Valley 15.2±0.2-13.0±0.3 million years, Mason Spur 12.8±0.4-11.4±0.2 million years, rocks below the summit of 6.13±0.20-~1.00 million years and 4.51±0.31-0.02 million years on other formations. Some of these eruptions may have deposited volcanic ash over the McMurdo Sound area. Even older activity at Mount Morning may be recorded in volcanic deposits from Cape Roberts which go back to 24.1 million years ago. This is a long lifespan for a volcano by Antarctic standards, and may be due to tectonic factors that kept magma generation focused on Mount Morning for a long time. Loading by glaciers may have influenced volcanic activity at Mount Morning.
Volcanic activity has been subdivided into two phases separated by a hiatus, an early phase lasting between 11.4±0.2-18.7±0.3 million years ago and a late phase from 6.13±0.02 million years ago to almost present-day. These phases are also known as the phase I or the Mason Spur Lineage, and as the phase II or the Riviera Ridge Lineage. The early phase produced mildly alkaline volcanic rocks, the late phase which makes up most of the outcrops strongly alkaline rocks. The older rocks have undergone significant glaciation, while the younger ones are largely uneroded and make up the present-day edifice. Volcanic activity mostly occurred under the atmosphere, with the exception of some lavas that may have been erupted in a subaqueous environment and hyaloclastites which have been used to infer that glaciers existed there 15.4 million years ago. Volcanic activity was focused along geologic lineaments on Mount Morning, which were reused during more recent eruptions.
Eruptions took place at Mount Morning about 20,000 years ago, forming well-preserved cinder cones. In the 1960s thermal anomalies were observed at Gandalf Ridge, implying that the volcano may still be active, although ground surveys did not detect fumarolic activity. Thus, Mount Morning was considered dormant by Martin, Cooper and Dunlap 2010 and might be the source of tephra layers found in the area.
History and name
- "Antarctica Ultra-Prominences" Peaklist.org. Retrieved 2012-08-01.
- Martin, Cooper & Dunlap 2010, p. 359.
- "Morning". Global Volcanism Program. Smithsonian Institution. Retrieved 2020-03-19.
- Martin & Cooper 2010, p. 515.
- Martin, Cooper & Dunlap 2010, p. 357.
- Martin, Cooper & Price 2013, p. 129.
- Paulsen & Wilson 2009, p. 1074.
- LeMasurier et al. 1990, p. 124.
- Paulsen & Wilson 2009, p. 1072.
- LeMasurier et al. 1990, p. 23.
- Paulsen & Wilson 2009, p. 1075.
- Martin, Cooper & Price 2013, p. 135.
- Paulsen & Wilson 2009, p. 1077.
- Paulsen & Wilson 2009, p. 1078.
- Paulsen & Wilson 2009, p. 1081.
- Paulsen & Wilson 2009, p. 1073.
- Christ & Bierman 2020, p. 33.
- Martin, Cooper & Dunlap 2010, pp. 359-360.
- Martin, Cooper & Dunlap 2010, pp. 360-361.
- Martin, Cooper & Dunlap 2010, p. 360.
- Martin & Cooper 2010, p. 519.
- Powell 2008, p. 1.
- Martin, Cooper & Dunlap 2010, p. 368.
- Brook et al. 1995, p. 51.
- Paulsen & Wilson 2009, p. 1071.
- Martin, Cooper & Dunlap 2010, p. 358.
- Martin, Cooper & Dunlap 2010, p. 361.
- Martin, Cooper & Dunlap 2010, pp. 361-362.
- Martin, Cooper & Price 2013, p. 142.
- Claridge & Campbell 2008, p. 71.
- Martin, Cooper & Dunlap 2010, p. 366.
- Martin, Cooper & Dunlap 2010, p. 367.
- Griener et al. 2015, p. 75.
- Martin, Cooper & Dunlap 2010, p. 364.
- Martin, Cooper & Price 2013, p. 128.
- Tingey 1982, p. 185.
- Paulsen & Wilson 2009, p. 1083.
- Martin, Cooper & Dunlap 2010, p. 369.
- Lyon & Giggenbach 1974, p. 511.
- Keys, Anderton & Kyle 1977, p. 993.
- GNIS 2020, p. 1.
- Brook, Edward J.; Kurz, Mark D.; Ackert, Robert P.; Raisbeck, Grant; Yiou, Françoise (1 March 1995). "Cosmogenic nuclide exposure ages and glacial history of late Quaternary Ross Sea drift in McMurdo Sound, Antarctica". Earth and Planetary Science Letters. 131 (1): 41–56. doi:10.1016/0012-821X(95)00006-X. ISSN 0012-821X.
- Christ, Andrew J.; Bierman, Paul R. (1 January 2020). "The local Last Glacial Maximum in McMurdo Sound, Antarctica: Implications for ice-sheet behavior in the Ross Sea Embayment". GSA Bulletin. 132 (1–2): 31–47. doi:10.1130/B35139.1. ISSN 0016-7606.
- Claridge, G. G. C.; Campbell, I. B. (15 March 2008). "Zeolites in Antarctic soils: Examples from Coombs Hills and Marble Point". Geoderma. 144 (1): 66–72. doi:10.1016/j.geoderma.2007.10.009. ISSN 0016-7061.
- "Mount Morning". USGS.
- Griener, Kathryn W.; Warny, Sophie; Askin, Rosemary; Acton, Gary (1 April 2015). "Early to middle Miocene vegetation history of Antarctica supports eccentricity-paced warming intervals during the Antarctic icehouse phase". Global and Planetary Change. 127: 67–78. doi:10.1016/j.gloplacha.2015.01.006. ISSN 0921-8181.
- Keys, J.R.; Anderton, P.W.; Kyle, P.R. (September 1977). "Tephra and debris layers in the Skelton Neve And Kempe Glacier, South Victoria Land, Antarctica". New Zealand Journal of Geology and Geophysics. 20 (5): 971–1002. doi:10.1080/00288306.1977.10420692.
- LeMasurier, W.E.; Thomson, J.W.; Baker, P.E.; Kyle, P.R.; Rowley, P.D.; Smellie, J.L.; Verwoerd, W.J., eds. (1990). "Volcanoes of the Antarctic Plate and Southern Oceans". Antarctic Research Series. doi:10.1029/ar048. ISSN 0066-4634.
- Lyon, G. L.; Giggenbach, W. F. (1 July 1974). "Geothermal activity in Victoria Land, Antarctica". New Zealand Journal of Geology and Geophysics. 17 (3): 511–521. doi:10.1080/00288306.1973.10421578.
- Martin, Adam P.; Cooper, Alan F.; Dunlap, W. James (1 April 2010). "Geochronology of Mount Morning, Antarctica: two-phase evolution of a long-lived trachyte-basanite-phonolite eruptive center". Bulletin of Volcanology. 72 (3): 357–371. doi:10.1007/s00445-009-0319-1. ISSN 1432-0819.
- Martin, Adam P.; Cooper, Alan F. (October 2010). "Post 3.9 Ma fault activity within the West Antarctic rift system: onshore evidence from Gandalf Ridge, Mount Morning eruptive centre, southern Victoria Land, Antarctica". Antarctic Science. 22 (5): 513–521. doi:10.1017/S095410201000026X – via ResearchGate.
- Martin, Adam P.; Cooper, Alan F.; Price, Richard C. (1 December 2013). "Petrogenesis of Cenozoic, alkalic volcanic lineages at Mount Morning, West Antarctica and their entrained lithospheric mantle xenoliths: Lithospheric versus asthenospheric mantle sources". Geochimica et Cosmochimica Acta. 122: 127–152. doi:10.1016/j.gca.2013.08.025. ISSN 0016-7037.
- Paulsen, Timothy S.; Wilson, Terry J. (1 July 2009). "Structure and age of volcanic fissures on Mount Morning: A new constraint on Neogene to contemporary stress in the West Antarctic Rift, southern Victoria Land, AntarcticaStructure and age of volcanic fissures in West Antarctica". GSA Bulletin. 121 (7–8): 1071–1088. doi:10.1130/B26333.1. ISSN 0016-7606.
- Powell, Hugh (25 June 2008). "Earth, Wind, and Fire in Antarctica". Oceanus. Woods Hole Oceanographic Institution.
- Tingey, R. J. (1982). "The development and fluctuation of Antarctica's Cainozoic glaciation—the terrestrial record" (PDF). Australian Meteorological Magazine. 30 (2): 185.
- "Skiing the Pacific Ring of Fire and Beyond". Amar Andalkar's Ski Mountaineering and Climbing Site. 2007 . Retrieved 14 January 2005.
- Nyland, Roseanne E. (2011). Evidence for early-phase explosive basaltic volcanism at Mt. Morning from glass-rich sediments in the ANDRILL AND-2A core and possible response to glacial cyclicity (Thesis). Bowling Green State University.
- Martin, Adam Paul (2009-08-22). Mt. Morning, Antarctica : geochemistry, geochronology, petrology, volcanology, and oxygen fugacity of the rifted Antarctic lithosphere (Thesis thesis). University of Otago.
- Muncy, Harold Lee (1979). Geologic history and petrogenesis of alkaline volcanic rocks, Mt. Morning, Antarctica (Thesis). The Ohio State University.
- Paulsen, Hanne-Kristin. Lithological cross section through Mount Morning, Antarctica : a story told from xenolithic assemblies in a pyroclastic deposit (Thesis). Retrieved September 22, 2020.
- Sullivan, R.J. (2006). The geology and geochemistry of Seal Crater, Hurricane Ridge, Mount Morning, Antarctica (Thesis). University of Otago.
- Woerden, Van (2006). Volcanic geology and physical volcanology of Mount Morning, Antarctica (Thesis thesis). The University of Waikato.
- Polar Discovery: Mount Morning Lava Flows