Caledonian magmatism, Grampian Highlands: Difference between revisions
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Revision as of 07:00, 9 July 2015
From: Stephenson, D, and Gould, D. 1995. British regional geology: Grampian Highlands. Fourth edition. Keyworth, Nottingham: British Geological Survey.
Caledonian magmatism, introduction
In the discussion which follows, the established divisions of Older, Syntectonic and Newer Igneous Rocks used in the third edition of this handbook have largely been modified, to become a seven-fold division of the Caledonian Igneous Suite. Each division or grouping is linked to one or more episodes in the history of deformation events in the development of the Caledonian Orogen, which spanned the period from about 750 to 390 Ma. Excluding the events recorded by the tectonically emplaced Highland Border Complex (Chapter 9), the principal magmatic episodes were as follows:
The distribution of components of these groups, except for the minor intrusions, is shown on P915434; each is numbered and referenced in italics in the text, e.g. Dunfallandy Hill Granite (8).
The age of an intrusion with respect to the tectonic history of the surrounding rocks cannot always be determined from the local field evidence, especially in areas of poor exposure, and hence certain intrusions have been assigned to a suite by analogy with petrologically similar intrusions whose structural setting is better known. It should be noted also that the three latest suites were largely contemporaneous.
On P915434 | Name | Age (Ma) | Type | 87Sr/86Sri | Geochronological reference |
Pre-tectonic basic magmatism | |||||
2 | Tayvallich | 595 ± 4 | U/Pb Zr | — | Halliday et al., 1989 |
Syntectonic granitic intrusions | |||||
6 | Ben Vuirich | 590 ± 2 | U/Pb Zr | — | Rogers et al., 1989 |
8 | Dunfallandy Hill | 481 ± 15 | Rb/Sr WRI | 0.7185 ± 0.0008 | Pankhurst and Pidgeon, 1976 |
9 | Glen Clova (Rough Craig) | 549 ± 44 | Rb/Sr WR | 0.7166 ± 0.0024 | Robertson, 1994 |
Syn- to late-tectonic basic and ultramafic intrusions | |||||
14 | Insch | 489 ± 17 | Rb/Sr WRI | 0.7117 ± 0.0003 | Pankhurst, 1970 |
23 | Huntly | 476 ± 5 | K/Ar Bi | — | Brown et al., 1965 |
27 | Haddo House | 491 ± 6 | K/Ar Bi | — | Brown et al., 1965 |
Late-tectonic granitoid intrusions | |||||
(i) North-eastern biotite-muscovite-granites | |||||
26 | Belhelvie pegmatites | 472 ± 5 | Rb/Sr WRI | 0.7185 ± 0.0016 | van Breemen and Boyd, 1972 |
36 | Kemnay | 411 ± 7 | Rb/Sr Mins | 0.715 ± 0.002 | Bell, 1968 |
37 | Aberdeen | 470 ± 1 | U/Pb Mon | — | Kneller and Aftalion, 1987 |
38 | Auchlee | 439 ± 7 | Rb/Sr Mins | 0.733 ± 0.004 | Bell, 1968 |
40 | Strichen | 475 ± 5 | U/Pb Mon | — | Pidgeon and Aftalion, 1978 |
455 ± 22 | Rb/Sr WRI | 0.7172 ± 0.0011 | Pankhurst, 1974 | ||
42 | Aberchirder | 444 ± 9 | Rb/Sr WRI | 0.7157 ± 0.0008 | Pankhurst, 1974 |
43 | Longmanhill | 470 ± 50 | Rb/Sr WRI | — | Pankhurst, 1974 |
(ii) North-western biotite-muscovite-granites | |||||
46 | Ardclach | 475 ± 7 | U/Pb Mon | — | Zaleski, 1983 |
47 | Moy (main phase) | 455 + 27/ -15 | Rb/Sr WR + U/Pb Mon | 0.7185 ± 0.0001 | Zaleski, 1983 |
49 | Glen Kyllachy | 443 + 5/-15Rb/Sr | WR/Bi | 0.7176 ± 0.0004 | van Breemen and Piasecki, 1983 |
50 | Maol Chnoc | 436 ± 8 | Rb/Sr Mins | 0.717 | Clayburn, 1981 |
51 | Strathspey | 437 ± 16 | K/Ar Bi | — | Miller and Brown, 1965 |
52 | Loch Laggan | 439 ± 7 | Rb/Sr Mins | 0.705 - 0.718 | Clayburn, 1981 |
(iii) North-eastern diorites to granodiorites | |||||
53 | Kennethmont | 453 ± 4 | Rb/Sr WRI | 0.7145 ± 0.0013 | Pankhurst, 1974 |
Post-tectonic granitoid intrusions | |||||
(i) South Grampian Suite | |||||
56 | Garabal Hill–Glen Fyne | 406 ± 41 | Rb/Sr WRMI | 0.705 ± 0.003 | Summerhayes, 1966 |
Garabal Hill–Glen Fyne | 429 ± 22 | U/Pb Zr | — | Rogers and Dunning, 1991 | |
57 | Arrochar | 426 ± 33 | U/Pb Sph | — | Rogers and Dunning, 1991 |
65 | Comrie | 408 ± 5 | Rb/Sr WRMI | 0.705 - 0.707 | Turnell, 1985 |
Rubha Mor (Appinite pipe) | 427 ± 3 | U/Pb Sph | — | Rogers and Dunning, 1991 | |
(ii) Argyll Suite | |||||
66 | Moor of Rannoch | 408 ± 18 | K/Ar Bi; Rb/Sr WRMI | 0.7048 | Miller and Brown, 1965; Clayburn, 1981 |
67 | Strath Ossian | 405 ± 9 | Rb/Sr WRMI | 0.7059 | Clayburn, 1981 |
400 ± 10 | U/Pb Zr | — | Pidgeon and Aftalion, 1978 | ||
68 | Ballachulish | 406 ± 34 | Rb/Sr WRI | 0.7040 ± 0.0002 | Haslam and Kimbell, 1981 |
72 | Etive | 401 ± 64 | Rb/Sr WRI | 0.7058 ± 0.0004 | Clayburn et al., 1983 |
396 ± 125 | Rb/Sr WRI | 0.7055 ± 0.0005 | Clayburn et al., 1983 | ||
74 | Foyers | c.415 | various | — | Pankhurst, 1979 |
405 ± 86 | Rb/Sr WRMI | c. 0.707 | Clayburn, 1981 | ||
403 ± 97 | Rb/Sr WRMI | c. 0.7045 | Clayburn, 1981 | ||
75 | Findhorn | 413 ± 5 | Rb/Sr WRMI | c. 0.706 | van Breemen and Piasecki, 1983 |
77 | Corrieyairack | 434 ± 9 | Rb/Sr WRMI | 0.7056 | Clayburn, 1981 |
78 | Allt Crom | c. 405 | Rb/Sr WR | 0.7056 | Clayburn, 1981 |
81 | Crathes | 420 ± 2 | K/Ar Bi | — | Brown et al., 1965 |
(iii) Cairngorm Suite | |||||
87 | Moy (Saddle Hill) | 407 ± 5 | Rb/Sr WRI | 0.7081 ± 0.0002 | Zaleski, 1983 |
90 | Ben Rinnes | 411 ± 3 | Rb/Sr WRI | 0.7072 ± 0.0020 | Zaleski, 1985 |
93 | Monadhliath | 419 ± 5 | Rb/Sr WRI | 0.7058 ± 0.0008 | Harrison and Hutchinson, 1987 |
94 | Cairngorm | 408 ± 3 | Rb/Sr WRI | 0.7062 ± 0.0004 | Harmon et al., 1984 |
95 | Lochnagar | 415 ± 5 | Rb/Sr WRI | 0.7065 ± 0.0002 | Halliday et al., 1979 |
96 | Glen Gairn | 404 ± 6 | Rb/Sr WRI | 0.7081 ± 0.0015 | Harrison and Hutchinson, 1987 |
98 | "Mount Battock" | 416 ± 4 | Rb/Sr WRI | 0.7058 ± 0.0004 | Harrison and Hutchinson, 1987 |
102 | Hill of Fare | 413 ± 3 | Rb/Sr WRI | 0.7057 ± 0.0003 | Halliday et al., 1979 |
103 | Bennachie | 400 ± 4 | Rb/Sr WRI | 0.7062 ± 0.0004 | Darbyshire and Beer, 1988 |
104 | Middleton | 398 ± 19 | Rb/Sr WR | 0.7092 ± 0.0181 | Darbyshire and Beer, 1988 |
105 | "Peterhead | 406 ± 13 volcanic rock | Rb/Sr Mins | — | Bell, 1968 |
Lower Old Red Sandstone volcanic rocks | |||||
108 | Lorn Plateau | 400 ± 5 | Rb/Sr WRI | 0.7047 | Clayburn et al., 1983 |
421 - 413 | Ar degassing | — | Thirlwall, 1988 | ||
NB All Rb/Sr and K/Ar ages recalculated using the decay constants of Steiger and Jaeger, 1977. WR = Whole rock (no isochron) WRI = Whole rock isochron WRMI = Whole rock – mineral isochron Mins = Mineral age (no isochron) Bi = Biotite Zr = Zircon Mon = Monazite Sph = Sphene | |||||
1 Average for complex 2 Appinitic diorite 3 Appinite 4 Meall Odhar Granite 5 Central Starav Granite 6 Tonalite and granodiorite 7 Granite. |