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308:, which is the main argument for them having formed a single continent 3 Ga. The Kaapvaal Craton became stable around 3.1 Ga. The Pilbara Craton is not well defined but formed around 3 Ga. Three cratons in East Antarctica are of similar age but not well known. These cratons share similar geological histories and are therefore assumed to have formed Vaalbara.
297:
334:, also formed around 3 Ga but underwent extensive magmatism around 2.5 Ga not seen elsewhere, and their relation to Ur is unclear. Ur, nevertheless, became larger around 2.5 Ga, and this so-called "Expanded Ur" incorporated the Zimbabwe and Yilgarn cratons.
327:-age deformation, and because there is no evidence of ocean closure in this belt (except in Africa), the 1 Ga orogen can be assumed to be intra-continental. Consequently, the southern margin of Ur is now below the Antarctic ice cover.
207:
in western
Australia—next to each other based on stratigraphic similarities. In Roger's configuration of Ur, these cratons are placed far apart in their Gondwana configuration. This configuration is contradicted by widespread
353:
between the
Bundelkhand-Aravalli block and the other Archaean blocks. 2.8–2.6 Ga metamorphism in Dharwar and Bundelkhand indicate that the stabilisation of Ur probably continued until the end of that period.
168:
until the break-up of
Gondwana. In other reconstructions, however, India and East Antarctica did not collide until Rodinia formed 1.1 Ga. Furthermore, in the early Archaean
901:
227:
cratons, is distinct from both
Vaalbara and Ur. Vaalbara and Zimgarn, according to this proposal, both disintegrated about 2.1–2.0 Ga to reassemble as the
231:
and West
Australian cratons 2.5–1.5 Ga. Smirnov et al. based this reconstruction on: (1) Zimgarn was still undergoing cratonisation when an extensive
532:"Archaean granulite facies metamorphism at the Singhbhum Craton–Eastern Ghats Mobile Belt interface: implication for the Ur supercontinent assembly"
26:
269:, since it is the first continent in his tectonic reconstructions. Other Archaean continental assemblages are considerably younger: Arctica (
574:"Palaeomagnetic and rock magnetic study of charnockites from Tamil Nadu, India, and the 'Ur'protocontinent in Early Palaeoproterozoic times"
293:) consolidated around 2.1 Ga. In some reconstructions the shields of Ur stayed near each other until the Mesozoic break-up of Gondwana.
192:, did not exist or were rare. This makes most proposed Archaean supercontinents controversial, including Rogers's 3 Ga supercontinent.
330:
Two cratons in India of equal age, Western
Dharwar and Singhbhum, were also part of Ur. Two other Indian cratons, Eastern Dharwar and
894:
235:
developed over
Vaalbara; (2) the magmatic signatures are different for the two supercratons during the period 2.6–2.0 Ga; and (3)
189:
1650:
1655:
769:"Trading partners: tectonic ancestry of southern Africa and western Australia, in Archean supercratons Vaalbara and Zimgarn"
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255:), western Australia (Kilbaran and Pilbara), and southern Africa (Kaapvaal and Zimbabwe) which indicate that these
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124:. In more recent works geologists often refer to both Ur and other proposed Archaean continental assemblages as
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eon around 3.1 billion years ago (Ga). In a reconstruction by Rogers, Ur is half a billion years older than
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Three small areas in the Indian Ocean coast of
Antarctica are also about 3 Ga old: western
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was 200 °C hotter than today, and many characteristics of modern tectonics, such as
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shields were close together in the mid-Archaean. The name "Ur", from the German prefix
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Mahapatro, S. N.; Pant, N. C.; Bhowmik, S. K.; Tripathy, A. K.; Nanda, J. K. (2012).
491:
812:"Review of global 2.1–1.8 Ga orogens: implications for a pre-Rodinia supercontinent"
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679:
Rogers, J. J. W. (1996). "A history of continents in the past three billion years".
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The cratons that had become stable around 3 Ga were all in the same region within
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Mondal, S.; Piper, J. D. A.; Hunt, L.; Bandyopadhyay, G.; Mallik, S. B. (2009).
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Smirnov, A. V.; Evans, D. A.; Ernst, R. E.; Söderlund, U.; Li, Z. X. (2013).
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Important geological similarities link now remote
Archaean cratons in India (
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120:, making it a supercontinent despite probably being smaller than present-day
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and, in the early period of its existence, probably the only continent on
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Hypothetical
Archaean supercontinent from about 3.1 billion years ago
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128:. Ur can, nevertheless, be half a billion years younger than
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492:"Validating the existence of Vaalbara in the Neoarchean"
810:
Zhao, G.; Cawood, P. A.; Wilde, S. A.; Sun, M. (2002).
385:, Implications for a pre-Rodinia supercontinent, p. 155
490:
de Kock, M. O.; Evans, D. A.; Beukes, N. J. (2009).
436:, Proposed Continents and Their Duration, pp. 94–95
215:Another possible supercraton, Zimgarn, proposed by
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53:
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406:
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614:"The supercontinent cycle: a retrospective essay"
612:Nance, R. D.; Murphy, J. B.; Santosh, M. (2014).
421:, Abstract; Discussion and conclusions, pp. 15–16
323:. Within Gondwana, these areas were in a belt of
212:collisional events between Australia and Africa.
337:The largest preserved parts of Ur are in India:
300:Conjectured map of Ur and succeeding landmasses
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239:latitudes for 2.7 Ga are slightly different.
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148:About 1.3–1.1 Ga, Ur joined the continents
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475:, Implication for Ur Assembly, pp. 329–330
243:Original concept and later interpretations
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397:, Pre-Rodinia supercontinents, pp. 11–13
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724:Rogers, J. J. W.; Santosh, M. (2003).
448:, The ‘Ur’ protocontinent, pp. 503–505
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265:meaning "original", was introduced by
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164:, Ur remained the nucleus of eastern
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726:"Supercontinents in Earth History"
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1437:Possible future supercontinents
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578:Journal of Asian Earth Sciences
516:10.1016/j.precamres.2009.07.002
281:) consolidated around 2.6 Ga,
1:
836:10.1016/S0012-8252(02)00073-9
753:10.1016/S1342-937X(05)70993-X
1215:Other prehistoric continents
598:10.1016/j.jseaes.2008.08.004
463:, Ur (~3000 Ma), pp. 358–360
347:Central Indian Tectonic Zone
136:Incompatible reconstructions
858:Zimmer, C. (January 1997).
660:Geological Society of India
160:. In the reconstruction of
156:to form the supercontinent
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190:ultra-high-pressure rocks
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1624:Chronology of continents
638:10.1016/j.gr.2012.12.026
144:Artistic depiction of Ur
203:in southern Africa and
1651:Former supercontinents
1385:Great Australian Bight
687:(1): 91–107, Chicago.
652:Rogers, J. J. (1993).
409:, Introduction, p. 145
373:, Rodinia, pp. 363–364
345:, and Singhbhum. The
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1656:Historical continents
816:Earth-Science Reviews
473:Mahapatro et al. 2012
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291:eastern South America
143:
1609:Continental fragment
1604:Regions of the world
776:Precambrian Research
496:Precambrian Research
219:and named after the
41:Historical continent
1566:Indian Subcontinent
1356:Submerged continent
828:2002ESRv...59..125Z
788:2013PreR..224...11S
745:2003GondR...6..357R
693:1996JG....104...91R
630:2014GondR..25....4N
590:2009JAESc..34..493M
508:2009PreR..174..145D
419:Smirnov et al. 2013
217:Smirnov et al. 2013
195:Reconstructions of
108:that formed in the
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681:Journal of Geology
536:Geological Journal
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1150:Prehistoric
1149:
1108:
1093:
1078:
1071:Afro-Eurasia
1063:
1025:
1010:
995:
980:
965:
950:
935:
869:. Retrieved
863:
839:. Retrieved
819:
815:
799:. Retrieved
779:
775:
756:. Retrieved
736:
732:
684:
680:
668:. Retrieved
666:(3): 217–222
663:
659:
641:. Retrieved
621:
617:
601:. Retrieved
581:
577:
561:. Retrieved
539:
535:
519:. Retrieved
499:
495:
468:
441:
414:
402:
390:
378:
366:
336:
329:
310:
303:
260:
246:
214:
194:
147:
126:supercratons
101:
100:
1452:Novopangaea
1320:South China
1300:North China
841:February 1,
643:February 1,
624:(1): 4–29.
434:Rogers 1996
343:Bundelkhand
341:, Dharwar,
287:West Africa
267:Rogers 1993
257:protolithic
210:Precambrian
178:blueschists
162:Rogers 1996
31:Ur, in the
1640:Categories
1588:See also:
1490:Hyperborea
1480:continents
1415:Seychelles
1400:Madagascar
1380:Doggerland
1275:Euramerica
1230:Asiamerica
958:Antarctica
911:Continents
483:References
319:, and the
277:, Ur, and
174:ophiolites
1561:Greenland
1425:Zealandia
1390:Jan Mayen
1375:Cathaysia
1295:Laurentia
1290:Laramidia
1280:Kalaharia
1235:Atlantica
1168:Kenorland
988:Australia
782:: 11–22.
717:128776432
558:127300220
325:Grenville
283:Atlantica
275:Laurentia
249:Singhbhum
186:eclogites
184:-bearing
182:lawsonite
154:Atlantica
122:Australia
33:Eoarchean
1619:Category
1485:Atlantis
1470:Mythical
1405:Mauritia
1370:Beringia
1255:Cimmeria
1250:Chilenia
1240:Avalonia
1220:Amazonia
1203:Vaalbara
1188:Pannotia
1173:Laurasia
1163:Gondwana
1158:Columbia
1086:Americas
871:March 1,
865:Discover
801:March 1,
758:March 1,
709:30068065
670:March 1,
603:March 1,
563:March 1,
521:March 1,
339:Aravalli
332:Bhandara
229:Kalahari
221:Zimbabwe
201:Kaapvaal
197:Vaalbara
166:Gondwana
130:Vaalbara
1646:Archean
1505:Meropis
1500:Lemuria
1315:Siberia
1265:Cuyania
1245:Baltica
1225:Arctica
1193:Rodinia
1183:Pangaea
1116:Oceania
1101:Eurasia
824:Bibcode
784:Bibcode
741:Bibcode
689:Bibcode
626:Bibcode
586:Bibcode
504:Bibcode
306:Pangaea
279:Siberia
271:Baltica
253:Dharwar
225:Yilgarn
205:Pilbara
158:Rodinia
114:Arctica
110:Archean
1541:Arabia
1536:Alaska
1476:, and
1447:Aurica
1442:Amasia
1305:Pampia
1003:Europe
943:Africa
715:
707:
556:
351:suture
315:, the
188:, and
49:3.1 Ga
46:Formed
1420:Sunda
1410:Sahul
1360:lands
1310:Sahul
915:Earth
772:(PDF)
729:(PDF)
713:S2CID
705:JSTOR
554:S2CID
358:Notes
118:Earth
1474:lost
1362:and
1178:Nena
973:Asia
873:2016
843:2016
803:2016
760:2016
672:2016
645:2016
605:2016
565:2016
523:2016
289:and
251:and
223:and
152:and
150:Nena
54:Type
913:of
832:doi
792:doi
780:224
749:doi
697:doi
685:104
634:doi
594:doi
544:doi
512:doi
500:174
262:ur-
35:Era
1642::
1510:Mu
1472:,
1198:Ur
862:.
830:.
820:59
818:.
814:.
790:.
778:.
774:.
747:.
735:.
731:.
711:.
703:.
695:.
683:.
664:42
662:.
658:.
632:.
622:25
620:.
616:.
592:.
582:34
580:.
576:.
552:.
540:47
538:.
534:.
510:.
498:.
494:.
453:^
426:^
273:,
180:,
176:,
102:Ur
20:Ur
1358:/
903:e
896:t
889:v
875:.
845:.
834::
826::
805:.
794::
786::
762:.
751::
743::
737:6
719:.
699::
691::
674:.
647:.
636::
628::
607:.
596::
588::
567:.
546::
525:.
514::
506::
285:(
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