Subduction and eduction of continental crust: major mechanisms during continent‐continent collision and orogenic extensional collapse, a model based on the south Norwegian Caledonides

Terra Nova - Tập 3 Số 3 - Trang 303-310 - 1991
Torgeir B. Andersen1, Bjørn Jamtveit1, John Dewey2, Eivind Swensson1
1Department of Geology, University of Oslo, 0316 Blindern, Oslo 3, Norway
2Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, UK

Tóm tắt

ABSTRACTDuring continental collision in the middle Silurian, the thickness of the lithosphere under the Caledonides of S. Norway was doubled by subduction of the western margin of Baltica, including the Western Gneiss Region, under Laurentia. Crustal rocks of the Baltic plate reached sub‐Moho depths of near 100 km or more as inferred from the presence of coesite in eclogites. Isostatic calculations indicate an average elevation of the mountain chain of about 3 km at this stage. The subducted lithosphere experienced vertical constrictional strains as a result of slab‐pull by its heavy and cold root. Eduction of the deeply buried crustal material was initiated by decoupling of the Thermal Boundary Layer in the subducted lithosphere. Isostatic rebound resulted in very rapid uplift (1–2 mm yr‐1), and the deep crust was exhumed, mainly by tectonic extensional stripping over a period of 30–40 Myr. The eduction was probably related to a rolling hinge, footwall uplift mechanism, and the early high‐pressure coaxial fabrics were overprinted by extensional simple shear as the deep crust reached middle and upper crustal levels. The model explains the present‐day normal crustal thickness under the exhumed deep rocks without necessarily invoking large‐scale lateral flow of material in the lower crust or igneous underplating.

Từ khóa


Tài liệu tham khảo

10.1029/TC009i005p01097

Andersen T.B., 1990, The Sunnfjord Melange, evidence of Silurian ophiolite accretion in the West Norwegian Caledonides, J. geol. Soc. London, 146, 59, 10.1144/gsjgs.147.1.0059

AndresenA.(1982)Stratigraphy and structural history of the Lower Paleozoic metasediments on Hardangervidda South Norway PhD thesis University of California Davis USA 260pp.

10.1130/0091-7613(1990)018<0223:RUACGI>2.3.CO;2

10.1016/0012-821X(87)90158-0

10.1016/0024-4937(90)90012-P

10.1016/0009-2541(85)90124-X

Austrheim H., 1988, The lower continental crust in continent‐continent collision zones; evidence from former deep seated section in Western Norway, Nor. geol. Unders. Spec. Publ., 3, 102

Bjørlykke K., 1983, Subsidence and tectonics in late Precambrian and Paleozoic sedimentary basins of southern Norway, Nor. geol. Unders. Bull., 380, 159

10.1098/rsta.1982.0039

10.2475/ajs.272.4.334

10.1007/978-94-009-2549-6_18

10.1029/TC007i005p00959

Carswell D.A., 1990, Eclogite Facies Rocks, 1, 10.1007/978-94-010-9263-0

10.1007/BF00381838

10.1098/rsta.1987.0010

10.1007/BF00375181

10.1111/j.1525-1314.1983.tb00265.x

10.1029/TC007i006p01123

10.1098/rsta.1988.0135

Enami M., 1990, Quartz pseudomorphs after coesite in eclogites from Shandong province, east China, Am. Miner., 75, 381

10.1098/rsta.1988.0089

10.1144/GSL.SP.1986.019.01.05

Gebauer D., 1985, The age and origin of some Norwegian eclogites: A U‐Pb zircon and REE study, Chem. Geol., 52, 227

10.1180/minmag.1987.051.361.01

Griffin W.L., 1985, The Caledonide Orogen—Scandinavia and related areas, 783

10.1038/285319a0

Griffin W.L., 1985, REE, Rb‐Sr and Sm‐Nd studies of Norwegian eclogites, Chem. Geol., 52, 249

10.1016/0191-8141(89)90069-2

Hamilton W.B., 1988, Detachment faulting in the Death Valley region, California and Nevada, Bull. geol. Soc. Ani., 1790, 51

10.1029/JB095iB08p12499

10.1007/BF00518032

10.1007/BF00306442

10.1111/j.1525-1314.1991.tb00509.x

10.1038/267017a0

Kullerud L., 1986, A compilation of radiometric age determinations from Western Gneiss Region, South Norway, Nor. geol. Unders. Bull., 406, 17

Lux D.R., 1985, K/Ar ages from the Basal Gneiss Region, Stadtlandet area, Western Norway, Norsk geol. Tidsskr., 65, 277

Mirwald P.W., 1980, Quartz‐coesite transition and the comparative friction measurements in piston‐cylinder apparatus using talcasimag‐glass (TAG) and NaCl high pressure cells, Neues Jb. Min. Monat-shefte, 10, 469

10.1016/0012-821X(90)90125-H

10.1144/GSL.SP.1989.045.01.17

10.1016/0009-2541(85)90125-1

10.1016/0024-4937(86)90026-5

10.1130/MEM164-p17

10.1029/TC005i002p00195

10.1130/0091-7613(1989)017<0540:ECOTCL>2.3.CO;2

10.1029/JB087iB02p00945

10.1144/GSL.SP.1987.028.01.35

10.1038/310641a0

Smith D.C., 1988, Eclogites and Eclogitefacies Rocks, 1

10.1111/j.1365-3121.1989.tb00325.x

10.1029/TC009i004p00903

Swensson E., 1991, Contact relationships between the Askvoll Group and the basement gneisses of the Western Gneiss Region (WGR), Sunnfjord, W. Norway, Norsk geol. Tidssk., 71

10.1016/0012-821X(87)90156-7

Thông tin
Thông tin xuất bản

Terra Nova

Tập 3 Số 3

303-310

Thông tin tác giả