Marinoan glaciation: Difference between revisions

{{short description|A periodPeriod of worldwide glaciation during the Cryogenian period.}}

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| doi = 10.1144/SP326.2|bibcode = 2009GSLSP.326...27S | s2cid = 129706604
}}</ref> An earlier and longer possible snowball phase, the [[Huronian glaciation]], is not shown here.

| doi = }}</ref> The corresponding time period, referred to as the Marinoan Epoch, spanned from the middle Cryogenian to the top of the [[Ediacaran]] in modern terminology. Mawson recognised a glacial episode within the Marinoan Epoch which he referred to as the Elatina glaciation after the 'Elatina Tillite' (now [[Elatina Formation]]) where he found the evidence.<ref name=Mawson1949>{{cite journal

| journal = [[Transactions of the Royal Society of South Australia]]

| doi = }}</ref> However, the term Marinoan glaciation came into common usage because it was the glaciation that occurred during the Marinoan Epoch, as distinct from the earlier glaciation during the Sturtian Epoch (the time period of deposition of the older Sturtian Series<ref name=Mawson1950 />).

The term Marinoan glaciation was later applied globally to any glaciogenic formations assumed (directly or indirectly) to correlate with Mawson's original Elatina glaciation in South Australia.<ref>{{Cite journal|lastlast1=Wen|firstfirst1=Bin|last2=Evans|first2=David A. D.|last3=Li|first3=Yong-Xiang|last4=Wang|first4=Zhengrong|last5=Liu|first5=Chao|date=2015-12-01|title=Newly discovered Neoproterozoic diamictite and cap carbonate (DCC) couplet in Tarim Craton, NW China: Stratigraphy, geochemistry, and paleoenvironment|journal=[[Precambrian Research]]|volume=271|pages=278–294|doi=10.1016/j.precamres.2015.10.006|bibcode=2015PreR..271..278W}}</ref> Recently, there has been a move to return to the term Elatina glaciation in South Australia because of uncertainties regarding global correlation and because an Ediacaran glacial episode (Gaskiers) also occurs within the wide-ranging Marinoan Epoch.<ref name=Williams2008>{{cite journal

| journal = [[Precambrian Research]]

| journal = [[Nature Geoscience]]

| issue=12|bibcode = 2008NatGe...1..817A }}</ref> There were three (or possibly four) significant ice ages during the late Neoproterozoic. These periods of nearly complete glaciation of Earth are often referred to as "Snowball Earth", where it is hypothesized that at times the planet was covered by ice {{convert|1|-|2|km|mi|abbr=on}} thick.<ref name="SciDaily2004">{{cite web|title=New Evidence Supports Three Major Glaciation Events In The Distant Past|url=https://www.sciencedaily.com/releases/2004/04/040421234349.htm|publisher=ScienceDaily|date=2004-04-22|accessdateaccess-date=2011-06-18}}</ref> Of these glaciations, the [[Sturtian glaciation]] was the most significant, whereas the Marinoan was a shorter, but still worldwide glaciation. Other Cryogenian glaciations were probably small and not global as compared to the Marinoan or Sturtian glaciations.

During the Marinoan glaciation, characteristic glacial deposits indicate that [[Earth]] suffered one of the most severe ice ages in its history. [[Glacier]]s extended and contracted in a series of rhythmic pulses, possibly reaching as far as the equator.<ref>{{cite web |title = Microfossil lineages support sloshy snowball Earth |author = Dave Lawrence |year = 2003 |publisher = Geotimes |url = http://www.agiweb.org/geotimes/apr03/WebExtra041803.html|accessdateaccess-date=2011-06-18}}</ref><ref>{{cite web|title=Global Glaciation Snowballed Into Giant Change in Carbon Cycle|url=https://www.sciencedaily.com/releases/2010/05/100501013533.htm|publisher=ScienceDaily|date=2010-05-02|accessdateaccess-date=2011-06-18}}</ref>

| journal = [[Nature (journal)|Nature]]

|bibcode = 2004Natur.429..646P }}</ref>| s2cid = 2205883

Even though much evidence has been lost through geological changes, field investigations show evidence of the Marinoan glaciation in China, [[Svalbard]] archipelago and South Australia. In [[Guizhou Province]], China, glacial rocks were found to be underlying and overlying a layer of [[volcanic ash]]es which contained [[zircon]] minerals, which could be dated through [[radioisotopes]]. Glacial deposits in South Australia are approximately the same age (about 630&nbsp;Ma), confirmed by similar stable [[carbon isotope]]s, mineral deposits (including sedimentary [[barite]]), and other unusual sedimentary structures.<ref name="SciDaily2004" /> Two [[diamictite]]-rich layers in the top {{convert|1|km|mi|abbr=on}} of the {{convert|7|km|mi|abbr=on}} Neoproterozoic strata of the northeastern Svalbard archipelago represent the first and final phases of the Marinoan glaciation.<ref>{{cite journal|url=http://geoweb.princeton.edu/people/maloof/downloads/marinoan.pdf|doi=10.1111/j.1365-2117.2004.00234.x|title=The Marinoan glaciation (Neoproterozoic) in northeast Svalbard|vauthors=Halverson GP, Maloof AC, Hoffman PF |journal=Basin Research|year=2004|volume=16|issue=3|pages=297–324|accessdateaccess-date=2011-06-18|bibcode=2004BasR...16..297H|citeseerx=10.1.1.368.2815|s2cid=53588955 |archive-date=2012-03-20|archive-url=https://web.archive.org/web/20120320222653/http://geoweb.princeton.edu/people/maloof/downloads/marinoan.pdf|url-status=dead}}</ref> In Uruguay, evidence of the Marinoan glaciation is known from dropstones, diamictites, rhythmites, clast layers, and varve-like deposits.<ref name="PazosEtAl2003" />