476:
younger than ca. 806 Ma, which dates the deformation of the underlying basement
Badenoch Group. However, the relationship between the Badenoch Group and the lowermost Dalradian is unclear. A definitive depositional age of 601 ± 4 Ma is derived from the Tayvallich Volcanic Formation at the top of the Argyll Group and provides a useful age constrain for the uppermost Dalradian. A detrital zircon study provides useful maximum depositional age constraints for the lowermost Argyll group 1.1 km thick glaciogenic Port Askaig Formation. The age constraints suggest that the Port Askaig Formation correlates with the global ‘Sturtian’ Snowball Earth interval and spans ca. 717 – 660 Ma. At present, no conclusive ‘Marinoan’ aged glacial deposit has been found.
801:
660:
595:
242:
39:
858:
1215:
513:
The upper three groups are applied to
Ireland too; the Grampian Group is not recorded here nor in Shetland where the Dalradian is divided into a Clift Hills ‘Division’ which equates to the Southern Highland Group, a Whiteness ‘Division’ which equates to the Argyll Group and a Scatsta ‘Division’ which
573:
The
Trossachs Group as defined lies conformably above rocks of the Southern Highlands Group just northwest of the Highland Boundary Fault. Most of the outcrops of the Trossachs Group are fault-bounded, making overall correlation difficult. The oldest part of the group is interpreted to be the Keltie
475:
The
Dalradian Supergroup spans the late Tonian through to early Ordovician, however, there is an unfortunate lack of direct geochronological age constraints throughout the succession. There is some debate as to the age of the base of the Dalradian with some suggesting that sedimentation must be
816:(of the Islay Subgroup), is not present. Carbon isotope data from four metamorphosed limestones within this mainly siliclastic sequence, suggest that the entire Shetland sequence probably lies stratigraphically above the tillite marker, explaining its absence.
586:. The sedimentary rocks that lie unconformably above the ophiolite include the Dounans Limestone Formation that contains a fossil fauna of mid-Arenig age (near the boundary between the lower and middle Ordovician).
1146:
Prave, A.R.; Strachan, R.A.; Fallick, A.E. (2009). "Global C cycle perturbations recorded in marbles: a record of
Neoproterozoic Earth history within the Dalradian succession of the Shetland Islands, Scotland".
436:, intercalated among the sediments. The total thickness of this assemblage of rocks must be many thousand feet." The Dalradian Series (as then defined) included the "Eastern or Younger schists" of eastern
680:
In mainland
Scotland, the Appin and Argyll group sequences occupy the intermediate ground between the Southern Highland and Grampian groups. The Argyll Group is divided into four subgroups, thus:
1087:
Cawood, P.A.; Merale, R.E.; Strachan, R.A.; Tanner, P.W.G. (2012). "Provenance of the
Highland Border Complex: constraints on Laurentian margin accretion in the Scottish Caledonides".
1048:"Geometrical restoration of a late Neoproterozoic depositional framework and an intrabasinal unconformity in the Laurentian margin Dalradian Supergroup, Grampian Highlands, Scotland"
812:
The stratigraphic position of the sequence identified as
Dalradian in the Shetland Islands is uncertain, because the main marker within the sequence in Scotland and Ireland, the
1239:
565:
An additional group is recognised by some workers, the
Trossachs Group, forming the uppermost part of the succession, which outcrops close to the Highland Boundary Fault.
361:
proposed the name
Dalradian as a convenient provisional designation for the complicated set of rocks to which it was then difficult to assign a definite position in the
980:
Rugen, Elias J.; Pastore, Guido; Vermeesch, Pieter; Spencer, Anthony M.; Webster, David; Smith, Adam G. G.; Carter, Andrew; Shields, Graham A. (2 September 2024).
982:"Glacially influenced provenance and Sturtian affinity revealed by detrital zircon U–Pb ages from sandstones in the Port Askaig Formation, Dalradian Supergroup"
893:
Prave, A. R.; Fallick, A. E.; Kirsimäe, K. (3 March 2023). "Evidence, or not, for the late Tonian break-up of Rodinia? The Dalradian Supergroup, Scotland".
1244:
878:
578:
fossils have ben recovered. Apparently higher in the succession is the Margie Formation, which includes the Margie Limestone Member, which has yielded
836:
and involves the inversion of a large part of the succession. Caledonoid faulting on NE-SW lines affects the sequence across the entire area.
1130:
938:
Dempster, T. J.; Rogers, G.; Tanner, P. W. G.; Bluck, B. J.; Muir, R. J.; Redwood, S. D.; Ireland, T. R.; Paterson, B. A. (January 2002).
873:
1195:
1030:
800:
582:
fossils of early Ordovician age. Rocks of this group are interpreted to be everywhere in tectonic contact structurally below the
1259:
1219:
659:
940:"Timing of deposition, orogenesis and glaciation within the Dalradian rocks of Scotland: constraints from U–Pb zircon ages"
813:
1254:
199:
1234:
648:
583:
107:
628:
594:
241:
1249:
606:
492:
298:
89:
56:
401:
611:
The Southern Highland Group is found along the entire southeastern margin of the Grampian Highlands from
1160:
1096:
1059:
993:
954:
902:
485:
306:
118:
93:
639:. In Ireland the most extensive outcrop of the Southern Highland Group is to the north and south of
728:
217:
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732:
712:
464:
274:
262:
195:
179:
67:
833:
832:
with NE-SW aligned fold axes. Much of the southeastern part of the outcrop forms a part of the
534:. Metamorphism has been low to medium grade for the most part and resulted in the formation of
1191:
1126:
1026:
574:
Water Formation, which includes the Leny Limestone and Slate Member from which lower Cambrian
285:. The diverse assemblage of rocks which constitute the supergroup extend across Scotland from
270:
103:
1168:
1104:
1067:
1001:
962:
918:
910:
863:
One or more of the preceding sentences incorporates text from a publication now in the
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358:
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1100:
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is also formed from Dalradian rocks. Dalradian rocks extend across the north of
290:
266:
81:
245:
Andalusite crystals in Dalradian (Southern Highland Group) metamorphic rock at
1172:
1108:
1046:
Leslie, A.G.; Krabbendam, M.; Thomas, C.W.; Banks, C.J.; Clarke, S.M. (2024).
805:
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966:
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804:
Dalradian tilted metasedimentary rocks of the Hevda Phyllite Formation at
368:
In Archibald Geikie's words, "they consist in large proportion of altered
1123:
Bedrock Geology of the United Kingdom and Ireland (1:1,250,000 scale map)
663:
Dalradian metasediments of the Easdale Subgroup of the Argyll Group near
579:
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209:
183:
141:
52:
44:
1072:
1047:
1006:
981:
914:
923:
882:. Vol. 7 (11th ed.). Cambridge University Press. p. 777.
828:
folded the sequence in mainland Scotland into a series of major tight
778:
724:
664:
632:
624:
612:
456:
318:
310:
282:
246:
720:
547:
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377:
153:
1190:(Fourth ed.). London: The Geological Society. pp. 9, 92.
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593:
535:
286:
240:
716:
559:
527:
519:
433:
429:
373:
350:
330:
1025:(Fourth ed.). London: The Geological Society. p. 96.
631:. In Shetland, the Clift Hills Division extends from north of
523:
518:, the Dalradian sequence was originally deposited as marine
765:
The Grampian Group rocks occupy the ground south west from
727:
and much of the southeastern part of Mainland, east of the
715:
whilst the Scatsta ‘Division’ forms the western halves of
619:
and also in the northeast along the coastal strip between
711:
In Shetland the Whiteness ‘Division’ forms the core of
697:
whilst the Appin Group is divided into three subgroups:
488:
which in stratigraphic order i.e. youngest at top, are:
424:
schists and other allied varieties, which probably mark
647:. Smaller exposures occur as far to the southwest as
1125:(First ed.). British Geological Survey. 2017.
228:
223:
205:
175:
170:
160:
137:
132:
124:
114:
99:
73:
63:
23:
550:and semipelites. The Tayvallich Subgroup contains
731:. These rocks are also present in Ireland across
598:Folded rocks of the Southern Highland Group at
18:Sequence of rock strata in Scotland and Ireland
562:within the overlying Southern Highland Group.
8:
769:and extending down the Great Glen as far as
1240:Geologic supergroups of the United Kingdom
37:
20:
1071:
1005:
922:
463:of the central, eastern and southwestern
128:>20 km (summing the individual groups)
851:
849:
845:
514:equates to the Appin Group. Though now
781:. It is divided into three subgroups:
55:Ben Ledi Grit Formation, part of the
7:
325:coast, although obscured by younger
293:in the east and are confined by the
777:and, further east, as far south as
484:The supergroup is composed of four
1245:Geology of Highland (council area)
257:(informally and traditionally the
14:
1149:Journal of the Geological Society
1089:Journal of the Geological Society
1052:Journal of the Geological Society
986:Journal of the Geological Society
947:Journal of the Geological Society
895:Journal of the Geological Society
372:strata, now found in the form of
345:The land to the southeast of the
1213:
856:
455:, as well as the metamorphosed
412:and other rocks, together with
1186:Trewin, Nigel H., ed. (2002).
1021:Trewin, Nigel H., ed. (2002).
1:
814:Port Askaig Tillite Formation
281:and in the north and west of
200:Northern and Western Region
1276:
758:
669:
604:
301:to the southeast. Much of
1173:10.1144/0016-76492007-126
1109:10.1144/0016-76492011-076
649:Inishbofin, County Galway
627:, extending south to the
584:Highland Border Ophiolite
337:rocks in large sections.
297:to the northwest and the
108:Highland Border Ophiolite
36:
28:
739:and appear again in the
357:(Dalriada), and in 1891
249:Bay, north-east Scotland
1188:The Geology of Scotland
1023:The Geology of Scotland
879:Encyclopædia Britannica
655:Argyll and Appin groups
607:Southern Highland Group
590:Southern Highland Group
493:Southern Highland Group
299:Highland Boundary Fault
90:Southern Highland Group
57:Southern Highland Group
1260:Geological supergroups
967:10.1144/0016-764901061
809:
788:Corrieyairack Subgroup
667:
602:
250:
1222:at Wikimedia Commons
803:
704:Ballachulish Subgroup
701:Blair Atholl Subgroup
662:
597:
317:in the north east to
244:
68:Geological supergroup
558:basin and there are
307:Walls Boundary Fault
255:Dalradian Supergroup
119:Loch Ness Supergroup
24:Dalradian Supergroup
1165:2009JGSoc.166..129P
1101:2012JGSoc.169..575C
1073:10.1144/jgs2023-208
1064:2024JGSoc.181..208L
1007:10.1144/jgs2024-029
998:2024JGSoc.181...29R
959:2002JGSoc.159...83D
915:10.1144/jgs2022-134
907:2023JGSoc.180..134P
808:, on Unst, Shetland
791:Glenshirra Subgroup
785:Glen Spean Subgroup
684:Tayvallich Subgroup
432:-sheets or beds of
218:Republic of Ireland
30:Stratigraphic range
1255:Geology of Ireland
1157:Geological Society
810:
733:County Londonderry
668:
603:
465:Scottish Highlands
275:Grampian Highlands
263:stratigraphic unit
251:
196:County Londonderry
180:Grampian Highlands
110:(tectonic contact)
1235:Metamorphic rocks
1218:Media related to
1132:978-0-7518-3793-3
796:Shetland sequence
707:Lochaber Subgroup
461:sedimentary rocks
271:lithostratigraphy
239:
238:
104:Old Red Sandstone
43:Folded Dalradian
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826:Grampian orogeny
745:Nephin Beg Range
690:Easdale Subgroup
359:Archibald Geikie
295:Great Glen Fault
214:Northern Ireland
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872:, ed. (1911). "
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687:Crinan Subgroup
678:
670:Main articles:
657:
609:
592:
571:
569:Trossachs Group
482:
473:
446:Inverness-shire
363:stratigraphical
343:
289:in the west to
265:(a sequence of
94:Trossachs Group
59:
19:
12:
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5:
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1250:Neoproterozoic
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1209:External links
1207:
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1114:
1095:(5): 575–586.
1079:
1038:
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870:Chisholm, Hugh
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761:Grampian Group
759:Main article:
756:
755:Grampian Group
753:
751:of Connemara.
737:County Donegal
709:
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693:Islay Subgroup
691:
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605:Main article:
591:
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953:(1): 83–94.
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741:Ox Mountains
710:
696:
679:
672:Argyll Group
645:Lough Swilly
643:and west to
610:
572:
564:
512:
498:Argyll Group
483:
474:
402:conglomerate
367:
349:was the old
344:
305:east of the
258:
254:
252:
224:Type section
86:Argyll Group
32:: 725–470 Ma
15:
1159:: 129–135.
924:10023/27123
775:Loch Linnhe
749:Twelve Pins
676:Appin Group
641:Lough Foyle
637:Fitful Head
621:Fraserburgh
503:Appin Group
414:epidiorites
370:sedimentary
291:Fraserburgh
267:rock strata
156:, limestone
82:Appin Group
1229:Categories
840:References
629:Don valley
617:Stonehaven
600:Whitehills
442:Ross-shire
438:Sutherland
422:hornblende
420:-schists,
386:andalusite
365:sequence.
353:region of
347:Great Glen
341:Historical
329:lavas and
327:Palaeogene
235:(Dalriada)
165:diamictite
150:semipelite
1220:Dalradian
874:Dalradian
834:Tay Nappe
820:Structure
723:, all of
635:south to
576:trilobite
556:turbidite
554:within a
552:volcanics
544:psammites
540:phyllites
532:limestone
480:Sub-units
410:limestone
406:quartzite
398:greywacke
394:schistose
388:-schist,
384:-schist,
355:Dál Riata
269:) in the
259:Dalradian
233:Dál Riata
229:Named for
146:quartzite
133:Lithology
125:Thickness
100:Underlies
74:Sub-units
51:to lower
49:Ediacaran
45:phyllites
747:and the
713:Mainland
580:conodont
418:chlorite
390:phyllite
382:graphite
323:Atlantic
303:Shetland
279:Scotland
210:Scotland
184:Shetland
171:Location
142:Psammite
115:Overlies
53:Cambrian
1161:Bibcode
1097:Bibcode
1060:Bibcode
994:Bibcode
955:Bibcode
903:Bibcode
867::
779:Tyndrum
725:Whalsay
665:Ormsary
633:Lerwick
625:Portsoy
613:Kintyre
548:pelites
457:igneous
321:on the
319:Clifden
311:Ireland
283:Ireland
273:of the
261:) is a
247:Boyndie
206:Country
138:Primary
47:of the
1194:
1129:
1029:
861:
771:Corran
743:, the
721:Fetlar
536:slates
486:groups
453:gneiss
448:, the
396:grit,
378:schist
351:Celtic
176:Region
154:pelite
1058:(4).
992:(5).
943:(PDF)
901:(2).
830:folds
767:Elgin
560:lavas
520:sands
450:Moine
426:sills
331:tuffs
313:from
287:Islay
161:Other
1192:ISBN
1127:ISBN
1027:ISBN
824:The
806:Skaw
735:and
719:and
717:Unst
674:and
623:and
530:and
528:silt
524:muds
522:and
459:and
444:and
434:tuff
430:lava
400:and
374:mica
253:The
64:Type
1169:doi
1153:166
1105:doi
1093:169
1068:doi
1056:181
1002:doi
990:181
963:doi
951:159
919:hdl
911:doi
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