A. H. N. Rice

University of Vienna

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Bernhard Grasemann

University of Vienna

Cornelius Tschegg

University of Vienna

R. A. Gayer

Bavarian Center for Applied Energy Research

David Schneider

University of Ottawa

David L. Roberts

University of Kent

Fred Gaidies

Carleton University

Olivier K. A. Heldwein

Carleton University

Maria Thereza Akemi Guimarães Yogi

Carleton University

Galen P. Halverson

McGill University

C. Townsend

University of Stavanger

Cooperative Institutions

University of Vienna

California Institute of Technology

Gulf Research Center

Geological Survey of Austria

Centre National de la Recherche Scientifique

Egyptian Government

Heidelberg University

Pfizer (United States)

Carleton University

University of Oxford

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Continuous out-of-sequence ductile thrusting in the Norwegian Caledonides

Geological Magazine (1987)

A. H. N. Rice

Abstract Peak metamorphic conditions (up to sillimanite grade) in a unit of rocks beneath the evolving Kalak Nappe Complex (Finnmarkian Caledonides) developed prior to its incorporation as a nappe within the complex. The presence of displacement textures in peak metamorphic por-phyroblasts indicates that they grew in a hydrostatic stress regime and thus that the emplacement of tectonically higher units caused little or no deviatoric stress in the footwall rocks except close to the thrust plane. The developing geotherm in the incipient nappe was disrupted by the onset of thrusting (D2 deformation), which placed hot rocks on colder rocks. This led to the cessation of prograde metamorphism and accounts for the ubiquitous association of nappe emplacement and the meta morphic peak. Later deformation (D3/D4) occurred at lower grades (biotite/chlorite). Consideration of nappe translation rates and the likely erosion/cooling rates indicates that nappe movements must have occurred ‘continuously out-of-sequence’ within the Kalak Nappe Complex.

10.1017/s0016756800016277

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Citations (20)

Restoration of the External Caledonides, Finnmark, North Norway

Geological Society London Special Publications (2013)

A. H. N. Rice

Abstract Branch line restoration of the external Finnmark Caledonides, northern Norway, gives 232 km linear displacement of the Middle Allochthon, rising to 252 km when including thrusting-direction changes. A 108 km SSE/SE-directed deformation, mostly ductile, and 144 km ENE/ESE-directed deformation, mostly brittle, occurred. The North Varanger Region/Terrane restores to under Porsangerhalvøya, with the Trollfjorden–Komagelva Fault a possible precursor of the Kokelv Fault. Dextral offset on the Trollfjorden–Komagelva Fault was c. 207 km. Three major sediment depositional areas are recognized: Timan Basin (including Barents Sea–Løkvikfjellet, Einovskaya–Manjunnas–Digermulen and Laksefjord sub-basins); Gaissa Basin (including Finnmark Ridge and Baltica Coast); and Gaissa Promontory. The Barents Sea–Løkvikfjellet Sub-basin comprises 15.9 km of sediments of the North Varanger Terrane. The Einovskaya–Manjunnas–Digermulen Sub-basin comprises 4 km of Rybachi Terrane sediments overlain by the Manjunnas Group (3 km) and then a Gaissa Basin equivalent succession (4.2 km). The 7.7 km-thick Laksefjord Group (Laksefjord Sub-basin) lies directly WNW of the Finnmark Ridge. Maximum clastic sedimentation ( c. 3.7 km) in the Gaissa Basin was in the NE and maximum dolomite accumulation (235 m) in the SW, where the basin closed off. The Finnmark Ridge and Baltica Coast have condensed Gaissa Basin successions. The Gaissa Promontory lies north of the Gaissa Basin, probably with the same lithostratigraphy.

10.1144/sp390.18

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Citations (35)

The Gaissa Nappe, Finnmark, North Norway: an example of a deeply eroded external imbricate zone within the Scandinavian Caledonides

Journal of Structural Geology (1986)

C. Townsend David L. Roberts A. H. N. Rice R. A. Gayer

Allochthon

Greenschist

Décollement

10.1016/0191-8141(86)90061-1

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Citations (30)

Computer Modeling of the formation of Platinum-Group Element (PGE) Deposits in Dyke-Like Environments

11th SAGA Biennial Technical Meeting and Exhibition (2003)

M.L. Mbandezi A. H. N. Rice George C. Smith

Two-dimensional finite element computational fluid dynamic modelling of heat and mass transport in simplified intrusive sills and their feeder dykes is described herein. These simplified models resembled a complex intrusive system such as the Great Dyke of Zimbabwe.

Sill

Platinum group

Mass transport

10.3997/2214-4609-pdb.144.33

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Three for the neoproterozoic: sturtian, marinoan and varangerian glaciations

EGS - AGU - EUG Joint Assembly (2003)

A. H. N. Rice Galen P. Halverson Paul F. Hoffman

Acritarch

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Geometry of the Iapetus Baltoscandian continental margin; evidence for basement highs from the external imbricate zone.

EGUGA (2015)

A. H. N. Rice

Continental Margin

Basement

Margin (machine learning)

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Possible basement rocks in the Kalak Nappe Complex on Sørøy, Finnmark, N. Norway

Norsk Geologisk Tidsskrift (1990)

A. H. N. Rice Neuenheimer Feid

Viscous folded migmatites exposed between Hasfjord and Hoyvika in southem Soroy have both tield and petrographic features typical of the Eidvageid Supracrustal Sequence, a presumed basement unit in the Kalak Nappe Complex (Middle Allochthon). The distribution of the migmatites, the margins of which have been cut and hornfelsed by the Seiland Igneous Province, is consistent with their being part of the Eidvageid Sequence. If the migmatites on Soroy are basement, then their structures cannot be used to support either the idea of a pre-Caledonian Porsanger Orogeny or a pre-Caledonian emplacement age for the Seiland lgneous Province.

Migmatite

Basement

Allochthon

Orogeny

Dalradian

Sequence (biology)

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Citations (9)

An appraisal of the bo method in very-low grade metamorphic studies; the s. mayo caledonides, w. ireland

EAEJA (2003)

A. H. N. Rice David M. Williams

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Textural Sector-Zoning in Garnet: Theoretical Patterns and Natural Examples from Alpine Metamorphic Rocks

Mitteilungen der Österreichischen Geologischen Gesellschaft/Austrian journal of earth sciences (2007)

A. H. N. Rice Gerlinde Habler Elisabeth Carrupt Gianluca Cotza G. Wiesmayr

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Umbers, ocean crust and the Irish Caledonides: terrane transpression and the morphology of the Laurentian margin

Journal of the Geological Society (1997)

David M. Williams J. HARKIN A. H. N. Rice

The Clew Bay Complex of western Ireland contains a variety of rock types. These include schists possibly of Dalradian association, amphibolites and serpentinites of unknown age, cherts, volcanic rocks and graded gabbros of mid to upper Ordovician age and shales and sandstones of Silurian age. Intercalated within the cherts of the complex on Clare Island are chocolate-brown horizons of a porous rock, geochemically comparable to hydrothermal mid-ocean ridge metalliferous sediments (e.g. umbers). These cherts overlie volcanic rocks of MORB affinities with an island arc influence. The association exposed on Clare island of graded gabbros, MORB volcanic rocks, discontinuous carbonaceous horizons, cherts, umbers and deep water shales suggest the presence of a mid- to late Ordovician spreading centre now preserved as a dismembered ophiolite. The Clew Bay and Highland Border Complexes, both being parts of the Border Terrane, have many similarities including evidence of mid- to late Ordovician spreading, and it is suggested they formed in the same basin. However, they are dissimilar to both the South Mayo and Midland Valley Ordovician and Silurian rock associations, from which they are separated by a terrane boundary. The geochemical data and field associations do not indicate back-arc or intra-continental rifting. We suggest, therefore, that elements of older ocean crust became trapped inboard of a collided early Ordovician arc at re-entrants along the Laurentian margin. This trapped crust became the site of mid- to late Ordovician spreading. We also suggest that the site of this entrapment was to the northeast of the present positions of the Clew Bay and Highland Border Complexes and that they were emplaced into their present sites by end-Silurian transpression. This Laurentian margin morphology is compatible with that demonstrated for parts of the Newfoundland-Quebec sectors of the Appalachian sector of the orogen.

Transpression

Margin (machine learning)

10.1144/gsjgs.154.5.0829

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Citations (10)