Ellsworth Land Volcanic Group

Ellsworth Land Volcanic Group
Stratigraphic range: Toarcian
~183.4–177.5 Ma
TypeGeological formation
Sub-units
  • Mount Poster Formation
  • Sweeney Formation
UnderliesAnderson Formation (In part)
Thickness600–2000 m
Lithology
PrimarySilicic ignimbrites
OtherMudstone, Sandstone
Location
Coordinates74°S 65°E / 74°S 65°E / -74; 65
RegionAntarctic Peninsula
CountryAntarctica
ExtentEllsworth Land
Type section
Named forEllsworth Land
Named byHunter & Cantrill
Ellsworth Land Volcanic Group is located in Antarctica
Ellsworth Land Volcanic Group
Ellsworth Land Volcanic Group (Antarctica)

The Ellsworth Land Volcanic Group is a geological formation in the Latady Basin, Ellsworth Land, Antarctic Peninsula, with a calculated maximum depositional age of 183.4 ± 1.4 Ma, and a younger age around 177.5 ± 2.2 Ma, covering the Toarcian stage of the Jurassic Period in the Mesozoic Era.[1] This group is made up of volcanoclastic material, with the Mount Poster Formation, composed of silicic ignimbrites, and the Sweeney Formation, consisting of a mix of basaltic and sedimentary facies.[1]

The Mount Poster Formation was the first described in 1985, found on the locality of the same name, with exposures across northwestern areas of the southern Black Coast, Orville Coast, and eastern Ellsworth Land. It was found to be made of pyroclastic rocks along lava flows, all from intracaldera origin, interbedded with few sedimentary rocks. Originally, dating analyses indicated ages 189 ± 3 Ma-188 ± 3 Ma for the lowermost sections (Lower Pliensbachian), and 167 ± 3 Ma (Bathonian) for different locations within the formation, yet was later constrained to the Toarcian-only, between 183 and 177 Ma.[1] Due to this datations it was allocated in the lowermost section of the Jurassic Latady Basin layers, overlied by what was defined back then as "Latady Formation" (now Latady Group), now proven to be the Sweeney Formation.[2] The Sweeney Fm rocks outcrop on W Potter Peak, Mount Jenkins, Mount Edward, Mount Ballard and Mount Wasilewski. Local vulcanism is known to have continued in the Middle-Late Jurassic, as evidenced in the Latady Group deposition.[3]

The Ellsworth Land Volcanic Group belongs to the Patagonia-Antarctic Peninsula sequence, along the Mapple & Brennecke Formations and the N and Ellsworth-Whitmore terrane isolated granitoids.[4] This units form part of the wider first-stage event (V1) of the Chon Aike Province, proving connection with both areas in the Early Jurassic, with the closest unit in South America being the Tobífera and Lemaire Formations (Fuegian Andes), the Quemado Complex (Austral Patagonia), the Bahía Laura Volcanic Complex (Deseado Massif) and the Marifil,Cañadón Asfalto, Lonco Trapial & Garamilla Formation in Central-Northern Patagonia.[5][6][7][8] Other Units include Bajo Pobre, Cañadón Huemules and Roca Blanca Formations in Argentina.[9]

  1. ^ a b c HUNTER, M. A.; RILEY, T. R.; CANTRILL, D. J.; FLOWERDEW, M. J.; MILLAR, I. L. (2006-09-28). "A new stratigraphy for the Latady Basin, Antarctic Peninsula: Part 1, Ellsworth Land Volcanic Group". Geological Magazine. 143 (6): 777–796. Bibcode:2006GeoM..143..777H. doi:10.1017/s0016756806002597. ISSN 0016-7568.
  2. ^ LAUDON, T. S.; THOMSON, M. R. A.; WILLIAMS, P. L.; MILLIKEN, K. L.; ROWLEY, P. D.; BOYLES, J. M. (1983). "The Jurassic Latady Formation, southern Antarctic Peninsula". Antarctic Earth Science: 308–314.
  3. ^ ROWLEY, P. D.; SCHMIDT, D. L.; WILLIAMS, P. L. (1982). "Mount Poster Formation, southern Antarctic Peninsula and eastern Ellsworth Land" (PDF). Antarctic Journal of the United States. 17 (2): 38–39.
  4. ^ Craddock, John P.; Schmitz, Mark D.; Crowley, James L.; Larocque, Jeremiah; Pankhurst, Robert J.; Juda, Natalie; Konstantinou, Alexandros; Storey, Bryan (2016-08-05). "Precise U-Pb zircon ages and geochemistry of Jurassic granites, Ellsworth-Whitmore terrane, central Antarctica". Geological Society of America Bulletin. 129 (1–2): 118–136. doi:10.1130/b31485.1. ISSN 0016-7606.
  5. ^ PANKHURST, R. J.; RILEY, T. R.; FANNING, C. M.; KELLEY, S. P. (2000-05-01). "Episodic Silicic Volcanism in Patagonia and the Antarctic Peninsula: Chronology of Magmatism Associated with the Break-up of Gondwana". Journal of Petrology. 41 (5): 605–625. doi:10.1093/petrology/41.5.605. ISSN 1460-2415.
  6. ^ Navarrete, C.; Gianni, G.; Tassara, S.; Zaffarana, C.; Likerman, J.; Márquez, M.; Wostbrock, J.; Planavsky, N.; Tardani, D.; Perez Frasette, M. (2024). "Massive Jurassic slab break-off revealed by a multidisciplinary reappraisal of the Chon Aike silicic large igneous province". Earth-Science Reviews. 249: 104651. Bibcode:2024ESRv..24904651N. doi:10.1016/j.earscirev.2023.104651. ISSN 0012-8252.
  7. ^ Bouhier, V. E.; Franchini, M. B.; Caffe, P. J.; Maydagán, L.; Rapela, C. W.; Paolini, M. (2017). "Petrogenesis of volcanic rocks that host the world-class AgPb Navidad District, north Patagonian massif: comparison with the Jurassic Chon Aike volcanic province of Patagonia, Argentina". Journal of Volcanology and Geothermal Research. 338 (5): 101–120. doi:10.1016/j.jvolgeores.2017.03.016. Retrieved 9 August 2022.
  8. ^ Cabaleri, N.; Volkheimer, W.; Armella, C.; Gallego, O.; Silva Nieto, D.; Páez, M.; Koukharsky, M. (2010). "Estratigrafía, análisis de facies y paleoambientes de la Formación Cañadón Asfalto en el depocentro jurásico Cerro Cóndor, provincia del Chubut". Revista de la Asociación Geológica Argentina. 66 (3): 349–367. Retrieved 2022-09-05.
  9. ^ Riley, Teal R.; Burton-Johnson, Alex; Flowerdew, Michael J.; Poblete, Fernando; Castillo, Paula; Hervé, Francisco; Leat, Philip T.; Millar, Ian L.; Bastias, Joaquin; Whitehouse, Martin J. (2023). "Palaeozoic – Early Mesozoic geological history of the Antarctic Peninsula and correlations with Patagonia: Kinematic reconstructions of the proto-Pacific margin of Gondwana". Earth-Science Reviews. 236: 104265. Bibcode:2023ESRv..23604265R. doi:10.1016/j.earscirev.2022.104265. ISSN 0012-8252.