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Massive Australian Precambrian/Cambrian Impact Structure

From EverybodyWiki Bios & Wiki

Massive Australian Precambrian/Cambrian Impact Structure
Massive Australian Precambrian/Cambrian Impact Structure is located in Australia
Massive Australian Precambrian/Cambrian Impact Structure
Massive Australian Precambrian/Cambrian Impact Structure
MAPCIS' location. At 600 km across, it would be about ​1⁄7 the width of Australia
Impact crater/structure
ConfidenceHighly speculative[1]
Diameter600 kilometres (370 mi)
Agebetween 550 - 535 Ma (proposed)
Location
Coordinates25°33′S 131°23′E / 25.550°S 131.383°E / -25.550; 131.383Coordinates: 25°33′S 131°23′E / 25.550°S 131.383°E / -25.550; 131.383
⧼validator-fatal-error⧽


CountryAustralia
StateProposed Centre is located in the Northern Territory

The Massive Australian Precambrian/Cambrian Impact Structure also known as MAPCIS is a proposed impact structure based upon arguments presented by Daniel P. Connelly, a pharmacist,[2] at Geological Society of America meetings.[3] It is located approximately equidistant between Uluru (Ayers Rock) and Mount Conner in the Northern Territory of Australia. The structure is approximately 600 km (370 mi) in diameter. However, a hypothetical outermost ring 2,000 kilometres (1,200 mi) in diameter is claimed to be the result of undefined far field stresses.[4]

The name and theory of MAPCIS are proposed by pharmacist Daniel P. Connelly.[5] Connelly posits that the MAPCIS was caused by a marine oblique impact hitting continental crust with a North East to South West trajectory.[3] The collision created a complex peak ring crater with bilateral symmetries, approximately 600km in diameter (Connelly, 2009).[3]

The age of MAPCIS is constrained to late Ediacaran/Early Cambrian periods, between 550 and 535 million years ago (Ma).[6] This places the impact at just before the Cambrian explosion (542 Ma) of the current Phanerozoic eon (541 ma).[6] Due to its proposed size and date, the MAPCIS is linked to the Edicarian Extinction Event.[4] If confirmed as an impact crater, it would be the largest discovered on Earth.[7]

Evaluation[edit]

An impact structure is a crater-like geologic structure of deformed bedrock or sediment on a planetary surface produced by the impact of meteors or comets.[8] It differs from an impact crater as it includes the geologic structure produced rather than just the surface impression of the impact.[8] In most impact craters on Earth, the crater itself has been destroyed by erosion, leaving behind only deformed rock as evidence of the impact.[9]

According to the Earth Impact Database (EID) published by the Planetary and Space Science Centre, there are currently 190 confirmed impact sites as of April 2019.[7] The MAPCIS is not on the EID as it is currently unconfirmed, however it is listed as “unconfirmed." Unconfirmed impact sites are ranked using a three-step confidence level.[7] Level 1 is “probable”, level 2 is “potential”, and level 3 is “questionable.” Level 0 are confirmed structures listed on the EID. MAPCIS is listed as a class 3 “questionable” impact structure in David Rajmon’s Impact database from the Impact Field Studies Group (IFSG).[1] Rajmon specifically noted that this proposed impact structure is highly speculative and based upon numerous unfounded interpretations, including the impact origin of the pseudotachylites and alleged ejecta deposits.[1]

Discovery[edit]

In 2007, a pharmacist with a passion for geology named Daniel P. Connelly identified a 2,000km diameter ring on Google Earth. Connelly became very interested in the structure and its origins, and subsequently began investigating and scientific research.[5][3] Although scientific research existed prior to Connelly’s discovery in 2007, such as the 1969 Continental Drainage map of Australia which suggested the existence of an impact structure at this location,[10] Connelly was the first person to perform actively focus on this structure and perform research on it.[3] He utilised prior research as well as gathered primary evidence himself at the actual site for his scientific method.[4]

Following Connelly’s discovery on Google Maps in 2007, he travelled to Australia with his wife and eldest son to pursue this discovery with local experts of the Australian Impact Geology in Canberra.[4] To Connelly’s surprise, when presented with his findings, the experts could not confirm the existence of an impact structure and were not willing to pursue the subject further.[4] This motivated Connelly to personally investigate and perform his own research on the discovery. He flew to Alice Springs to both gather some primary evidence and have a nice holiday with his family.[4]

Date[edit]

A variety of scientific methods were utilised to estimate the age of MAPCIS. One is to look at nearby confirmed impact craters such as the Acraman crater. The Acraman crater located in the Gawler Ranges in South Australia, 800km from MAPCIS is dated at 580 Ma.[11] When a collision event occurs, an ejecta layer is formed surrounding the crater.[12] Previous research revealed that the ejecta layer from the Acraman impact is absent within the MAPCIS crater rim, however Acraman ejecta were found in deep drill cores 300km from the MAPCIS centre where the Gawler crater underlies the basin.[13][3] This provides evidence that the Acraman ejecta did make it as far as the MAPCIS Crater rim, however most of it has been erased due to some geological event.[6] This suggests that the MAPCIS occurred sometime after the Acraman impact.

The Mooracoochie volcanics located in the Warburton Basin in South Australia dated between 517 – 510 Ma formed a volcanic ring in the early Cambrian period together with the Kalkarindji LIP.[14][15] This volcanic ring is absent inside the MAPCIS crater rim, dating the MAPCIS prior to the formation of these volcanic structures.[16][6]

Both the evidence from the Acraman ejecta and the Mooracoochie volcanics constrains the age of the MAPCIS between 580 – 510 Ma. This range can be narrowed down further through zircon and monazite grain dating of the Musgrave block located between Northern Territory, South Australia, and Western Australia.[4] The Musgrave block was exposed by the Petermann Orogeny intracontinental event which occurred at around 535 – 550 Ma.[17] Complete exposed rock can be found near the centre of MAPCIS, narrowing the date of MAPCIS prior to the rock’s formation, somewhere between 535 – 550 Ma.[4]

Evidence[edit]

Visual Evidence[edit]

Prior to Connelly’s observation using Google Earth, there had been research and evidence supporting the existence of a massive ring impact structure in the South of Northern Territory. Using the 1969 Continental Drainage Map of Australia created by the Division of National mapping, O’Driscoll & Campbell hinted at the existence of a massive impact structure located in the centre of Australia but did not pursue the matter further.[10]

Following his initial discovery, Connelly decided to perform initial research using Google Earth and Microsoft Excel.[5] Taking the elevation data from Google Earth, Connelly was able to plot the elevations above sea level at 10km intervals along the bisects of the outer ring anomaly in Excel.[4] This revealed three key things. Firstly, the centre of the proposed impact was found within 100km of the intersection.[4] Secondly, there is a massive central highland located in the proposed impact structure area made up of basins and mountain ranges.[4] Thirdly, the outer rings have a width of over 100km but a depth between 50-100m deep. These findings were later confirmed by the 1969 Continental Drainage Map of Australia.[4]

Magnetic Evidence[edit]

The Total Magnetic Intensity (TMI) map of Uluru scaled 1:250,000 created by Geoscience Australia, shows a deep trench located between Uluru and Mount Conner, between Australia's Northern Territory and South Australia, at the location of the proposed MAPCIS.[4][18] The deep trench reveals the trajectory and final emplacement of the potential impact.[4] The trenches revealed in the TMI map for MAPCIS are similar to the Vredefort Impact Structure’s TMI map in terms of size, shape and directionality.[2] This magnetic evidence suggests the location and occurrence of an impact event.

Geological Evidence[edit]

Massive pseudotachylite breccia deposits can be found south of the MAPCIS impact centre.[4] These deposits may be formed through intense conditions such as an impact event.[19]

Pseudotachylite breccia deposits discovered at the Sudbury Impact Structure in Ontario, Canada.

Another piece of evidence for MAPCIS is the Iridium anomaly associated with the Precambrian-Cambrian boundary.[20] This boundary is the layer of sedimentary rock dated approximately 540 ma which marked the transition from the Precambrian period to the Cambrian period.[20] Iridium is a metal that is very rare on the surface of the Earth but is more common in molten rock deep in the Earth’s mantle and extra-terrestrial objects such as asteroids.[21] The Iridium anomaly refers to when Iridium levels are far greater than normal in a particular sedimentary rock layer.[22] The term is most commonly used to refer to the high Iridium levels in the Cretaceous-Paleogene boundary, and used as evidence for both the extra-terrestrial impact event as well as the extinction event in that time.[23] High levels of Iridium were discovered in the rocks within MAPCIS.[24]

The pseudotachylite breccia deposits from the Musgrave province were analysed for several platinum groups (PGEs) including Iridium.[24] The samples were prepared at the Virginia Commonwealth University and analysed at Bureau Veritas Commodities Canada.[24] The results demonstrated that Iridium levels in the deposits were orders of magnitudes higher than what is expected from the continental crust of that time and may be contributing to the iridium anomaly originally associated with the Precambrian-Cambrian boundary.[24] The high levels of Iridium in the samples are consistent with samples from other confirmed impact structures, suggesting an extra-terrestrial source or a mantle source for this enrichment of Iridium.[23] Further sampling and testing are currently planned to fully identify the source of this Iridium anomaly.[24]

The geological evidence for MAPCIS can also be compared to the confirmed Vredefort Impact structure to support the MAPCIS theory. Firstly, both the basins of the central impact area are of similar size and shape.[4][25] Secondly, the pseudotachylite breccia deposits which were not buried by the initial impact are mainly located down range from the impact centre and proportionally distanced  for both MAPCIS and Vredefort[4][25] Finally, there are bilateral areas that are angled slightly behind the oblique impact centres for both MAPCIS and Vredefort, where less impact forces were experienced.[4][25] The similarities in the geological evidence between the MAPCIS and the confirmed Vredefort Impact provide supporting evidence for the MAPCIS theory.

Gravimetric Evidence[edit]

Using gravimetric analysis to identify impact structures on astronomical bodies is a difficult process on planets with an active and dynamic geology such as Earth.[26] However, the process has seen significant development in the last few years through the efforts of NASA and other national space agencies.[27]

Using current gravimetric analytical methods, it is possible to create a model, at suitable scale, of the surface of a celestial body with key gravimetric information. We can then use these models and compare them to the models of other confirmed impact structures to identify similarities which can provide evidence of the existence of an impact structure.[4][27]

A gravimetric method of identifying impact structures is using Vertical Gravity Gradient (VGG) images.[28] VVG modelling shows multiple circular gravitational anomalies, with a central valley which indicate a multiple ring structure at least 600km in diameter.[4]

An exclusive feature of impact structures is the breakdown of crustal thickness (CT) which can be thousands of meters in difference compared to the CT values of the surrounding crust. This is evident in Chicxulub on Earth and Lowell on Mars.[29][30] Analysis of the models for MAPCIS demonstrates clearly a difference of more than 10,000 meters between the CT of the MAPCIS and the surrounding crust, which supports the existence of an impact structure.[4]

Ediacaran Extinction Event[edit]

The MAPCIS has been associated with the End-Ediacaran extinction event, which occurred approximately 542 ma.[4] This time period is particularly important in the history of life on Earth as it signalled the mass extinction of all Ediacaran biota and immediately pre-dated the Cambrian explosion which occurred approximately 541 ma.[31] The Cambrian explosion gave rise to almost all major animal phyla that are present today, it lasted between 13 – 25 million years and  resulted in the divergence of most modern metazoan phyla as well as other major groups of organisms.[32]

One piece of supporting evidence for this is the aforementioned Iridium anomaly in the sedimentary rock of MAPCIS.[24] Iridium Anomaly is usually associated with extra-terrestrial impact structures and is used to support the leading theory that an asteroid impact caused the Cretaceous–Paleogene extinction event.[33] This theory is highly speculative and further studies are required to confirm the theory.

See also[edit]

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References[edit]

  1. ↑ 1.0 1.1 1.2 Rajmon, David (2010). "Impact Database". Impact Field Studies Group (IFSG). Retrieved 12 June 2010.
  2. ↑ 2.0 2.1 Connelly, Daniel P. "Guide to MAPCIS for AGCC" (PDF). Retrieved 31 March 2019.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Connelly, Daniel P. (2009a). "The case for a massive Australian Precambrian/Cambrian impact structure (MAPCIS)". Geological Society of America Abstracts with Programs. 41 (3): 38. Archived from the original on 4 March 2016. Retrieved 17 September 2012. Unknown parameter |url-status= ignored (help)
  4. ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 "The Massive Australian Precambrian-Cambrian Impact Structure (MAPCIS) part one | AIG Journal". aigjournal.aig.org.au. Retrieved 2021-05-18.
  5. ↑ 5.0 5.1 5.2 "MAPCIS". austhrutime.com. Retrieved 2021-05-18. Unknown parameter |url-status= ignored (help)
  6. ↑ 6.0 6.1 6.2 6.3 Connelly, Daniel P. (2009b). "Age dating MAPCIS (Massive Australian Precambrian/Cambrian Impact Structure) a multi-modal indirect approach". Geological Society of America Abstracts with Programs. 41: 418. Archived from the original on 7 October 2017. Retrieved 6 April 2019. Unknown parameter |url-status= ignored (help)
  7. ↑ 7.0 7.1 7.2 "Australia". Planetary and Space Science Centre. Earth Impact Database. Fredericton, New Brunswick, Canada: University of New Brunswick. Archived from the original on 3 October 2014. Retrieved 12 June 2010. Unknown parameter |url-status= ignored (help)
  8. ↑ 8.0 8.1 "Fifth Edition of the Glossary of Geology Published". American Geosciences Institute. 2005-10-30. Retrieved 2021-05-18.
  9. ↑ Pappalardo, Robert T.; McKinnon, William B.; Khurana, K. (2009-07-30). Europa. University of Arizona Press. ISBN 978-0-8165-2844-8. Search this book on
  10. ↑ 10.0 10.1 O'Driscoll, E. S. T.; Campbell, I. B. (1996-07-31). "Mineral deposits related to Australian continental ring and rift structures with some terrestrial and planetary analogies". Global Tectonics and Metallogeny: 83–101. doi:10.1127/gtm/6/1996/83.
  11. ↑ "Acraman Impact Structure, South Australia". earthobservatory.nasa.gov. 2010-02-28. Retrieved 2021-05-18.
  12. ↑ Darling, David. "ejecta blanket". www.daviddarling.info. Retrieved 2021-05-18.
  13. ↑ Webster, L. J.; Hill, A. C.; Grey, K.; Gostin, V. A. (2004-02-01). "New records of Late Neoproterozoic Acraman ejecta in the Officer Basin". Australian Journal of Earth Sciences. 51 (1): 47–51. doi:10.1046/j.1400-0952.2003.01044.x.001. ISSN 0812-0099.
  14. ↑ Ware, Bryant D; Jourdan, Fred; Merle, Renaud; Chiaradia, Massimo; Hodges, Kyle (2018-04-01). "The Kalkarindji Large Igneous Province, Australia: Petrogenesis of the Oldest and Most Compositionally Homogenous Province of the Phanerozoic". Journal of Petrology. 59 (4): 635–665. doi:10.1093/petrology/egy040. ISSN 0022-3530.
  15. ↑ Abdullah, Rashed; Nugroho, Rio; Rosenbaum, Gideon; Doublier, Michael P.; Shaanan, Uri; Zwingmann, Horst (2019-05-01). "Evidence for Deformation in the Cambrian‐Ordovician Warburton Basin and Implications for the Evolution of the Tasmanides (Eastern Australia)". Tectonics. doi:10.1029/2018tc005124. Retrieved 2021-05-18.
  16. ↑ Connelly, Daniel P. (October 2013). "LIPS and Impact Events: A Connection Between Kalkarindji LIP, Mooracoochie Volcanics and MAPCIS?". Retrieved 18 May 2021. Unknown parameter |url-status= ignored (help)
  17. ↑ "Musgrave Block". austhrutime.com. Retrieved 2021-05-18.
  18. ↑ Gilder, Stuart A.; Pohl, Jean; Eitel, Michael (2018), Lühr, Hermann; Wicht, Johannes; Gilder, Stuart A.; Holschneider, Matthias, eds., "Magnetic Signatures of Terrestrial Meteorite Impact Craters: A Summary", Magnetic Fields in the Solar System: Planets, Moons and Solar Wind Interactions, Astrophysics and Space Science Library, Cham: Springer International Publishing, pp. 357–382, doi:10.1007/978-3-319-64292-5_13, ISBN 978-3-319-64292-5, retrieved 2021-05-18
  19. ↑ "Pseudotachylite in impact structures — generation by friction melting and shock brecciation?: A review and discussion". Earth-Science Reviews. 39 (3–4): 247–265. 1995-12-01. doi:10.1016/0012-8252(95)00033-X. ISSN 0012-8252.
  20. ↑ 20.0 20.1 "Precambrian-Cambrian Boundary - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2021-06-01.
  21. ↑ "Iridium - Element information, properties and uses | Periodic Table". www.rsc.org. Retrieved 2021-06-01.
  22. ↑ Zevenberg, Herman. "Iridium anomaly Iridium anomalies". www.paleontica.org. Retrieved 2021-06-01.
  23. ↑ 23.0 23.1 Goderis, Steven; Sato, Honami; Ferrière, Ludovic; Schmitz, Birger; Burney, David; Kaskes, Pim; Vellekoop, Johan; Wittmann, Axel; Schulz, Toni; Chernonozhkin, Stepan M.; Claeys, Philippe (2021-02-01). "Globally distributed iridium layer preserved within the Chicxulub impact structure". Science Advances. 7 (9): eabe3647. doi:10.1126/sciadv.abe3647. ISSN 2375-2548. PMID 33627429 Check |pmid= value (help).
  24. ↑ 24.0 24.1 24.2 24.3 24.4 24.5 Sikder, Arif; P., Connelly (2017-10-23). "IRIDIUM ANOMALY ASSOCIATED WITH MAPCIS?".
  25. ↑ 25.0 25.1 25.2 Huber, Matthew S.; Kovaleva, Elizaveta (2020-08-09). "Identifying Gaps in the Investigation of the Vredefort Granophyre Dikes: A Systematic Literature Review". Geosciences. 10 (8): 306. doi:10.3390/geosciences10080306.
  26. ↑ Innes, M. J. S. (1961). "The use of gravity methods to study the underground structure and impact energy of meteorite craters". Journal of Geophysical Research (1896-1977). 66 (7): 2225–2239. doi:10.1029/JZ066i007p02225. ISSN 2156-2202.
  27. ↑ 27.0 27.1 Zylberman, William (2018-02-19). Geophysical Study of Meteorite Impact Structures (Thesis).
  28. ↑ Kim, Seung-Sep; Wessel, Paul (2016). "New analytic solutions for modeling vertical gravity gradient anomalies". Geochemistry, Geophysics, Geosystems. 17 (5): 1915–1924. doi:10.1002/2016GC006263. ISSN 1525-2027.
  29. ↑ Neumann, G. A.; Zuber, M. T.; Wieczorek, M. A.; McGovern, P. J.; Lemoine, F. G.; Smith, D. E. (2004). "Crustal structure of Mars from gravity and topography". Journal of Geophysical Research: Planets. 109 (E8). doi:10.1029/2004JE002262. ISSN 2156-2202.
  30. ↑ "Mantle deformation beneath the Chicxulub impact crater". Earth and Planetary Science Letters. 284 (1–2): 249–257. 2009-06-30. doi:10.1016/j.epsl.2009.04.033. ISSN 0012-821X.
  31. ↑ "What caused the mass extinction of Earth's first animals? Unravelling mystery of the Ediacaran-Cambrian transition". ScienceDaily. Retrieved 2021-06-02.
  32. ↑ Canada, Royal Ontario Museum and Parks (2011-06-10). "The Burgess Shale". burgess-shale.rom.on.ca. Retrieved 2021-06-02.
  33. ↑ Goderis, Steven; Sato, Honami; Ferrière, Ludovic; Schmitz, Birger; Burney, David; Kaskes, Pim; Vellekoop, Johan; Wittmann, Axel; Schulz, Toni; Chernonozhkin, Stepan M.; Claeys, Philippe (2021-02-01). "Globally distributed iridium layer preserved within the Chicxulub impact structure". Science Advances. 7 (9): eabe3647. doi:10.1126/sciadv.abe3647. ISSN 2375-2548. PMID 33627429 Check |pmid= value (help).


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