A continuum model of crustal generation in Iceland - kinematic aspects

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G. Palmason


A steady-state plate-tectonic kinematic model of crustal accretion in Iceland is presented. It describes quantitatively the overall time-averaged movements of solid crustal elements during the accretion process, and correlates accretion parameters in the axial zone (width of lava deposition zone, total lava production rate, width of horizontal strain zone, spreading velocity, normal faulting) with structural properties in the Tertiary lava pile (lava dips, lava deposition rate, dyke fraction). The model is used, firstly, to predict the accretion parameters of the Tertiary volcanic zone on the basis of observed structural properties in the Tertiary lava pile; secondly, to predict possible structures of the lower crust in terms of a lava/intrusion ratio; thirdly, the model may be used to calculate the crustal temperature field caused by intrusions, but this application is outside the scope of the present paper. The model is essentially a further development of a previous one presented earlier by the author. The analysis, in terms of the model, of various published structural observations indicates that the width of lava deposition and the spreading rate in the Tertiary volcanic zone were consistent with the corresponding properties in the present-day volcanic zone. This may suggest a certain uniformity in the volcanic processes during the last 10-15 Ma. The visible Tertiary lava pile was, according to the model, deposited outside the innermost 50-km-wide central part of the volcanic zone, which may explain the difference in appearance between the two main volcanic regions of Iceland, i.e., the active volcanic zone and the Tertiary flood basalts. Furthermore, an analysis of possible structures of the lower crust, consistent with various surface observations, indicates a gradual rather than a sharp transition from an upper lava-dominated crust to a lower intrusion-dominated crust.

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Palmason, G. (1980). A continuum model of crustal generation in Iceland - kinematic aspects. Journal of Geophysics, 47(1), 7-18. Retrieved from https://journal.geophysicsjournal.com/JofG/article/view/69


Atwater, T. (1979) Constraints from the FAMOUS area concerning the structure of the oceanic section. In: Deep Drilling Results in the Atlantic Ocean: Ocean Crust, (M. Talwani, C.G. Harrison, D.E. Hayes, eds.) Am. Geophys. Union, Maurice Ewing Series 2:33-42

Atwater, T., Mudie, J.D. (1973) Detailed near-bottom geophysical study of the Gorda Rise. J. Geophys. Res. 78:8665-8686

Bjornsson, A., Saemundsson, K., Einarsson, P., Tryggvason, E., Gronvold, K. (1977) Current rifting episode in north Iceland. Nature 266:318-322

Bodvarsson, G., Walker, G.P.L. (1964) Crustal drift in Iceland. Geophys. J.R. Astron. Soc. 8:285-300

Cann, J.R. (1974) A model for the oceanic crustal structure developed. Geophys. J.R. Astron. Soc. 39:169-187

Daignieres, M., Courtillot, V., Bayer, R., Tapponnier, P. (1975) A model for the evolution of the axial zone of mid-ocean ridges as suggested by Icelandic tectonics. Earth Planet. Sci. Lett. 26:222-232

Harrison, C.G.A. (1968) Formation of magnetic anomaly patterns by dyke injection. J. Geophys. Res. 73:2137-2142

Herron, E.M., Talwani, M. (1972) Magnetic anomalies on the Reykjanes Ridge. Nature 238:390-392

Jakobsson, S.P. (1972) Chemistry and distribution pattern of Recent basaltic rocks in Iceland. Lithos 5:365-386

Johannesson, H. (1975) Structure and petrochemistry of the Reykjadalur central volcano and the surrounding areas, midwest Iceland. Ph.D. Thesis. Durham University, 273 pp.

Kidd, R.G.W. (1977) A model for the process of formation of the upper oceanic crust. Geophys. J .R. Astron. Soc. 50:149-183

Matthews, D.H., Bath, J. (1967) Formation of magnetic anomaly pattern of mid-Atlantic ridge. Geophys. J.R. Astron. Soc. 13:349-357

McDougall, I., Saemundsson, K., Johannesson, H., Watkins, N.D., Kristjansson, L. (1977) Extension of the geomagnetic polarity time scale to 6.5 m.y.: K-Ar dating, geological and paleomagnetic study of a 3,500 m lava succession in western Iceland. Geol. Soc. Am. Bull. 88:1-15

McDougall, I., Watkins, N.D., Kristjansson, L. (1976a) Geochronology and paleomagnetism of a Miocene-Pliocene lava sequence at Bessastadaa, eastern Iceland. Am. J. Sci. 276:1078-1095

McDougall, I., Watkins, N.D., Walker, G.P.L., Kristjansson, L. (1976b) Potassium-argon and paleomagnetic analysis of Icelandic lava flows: Limits on the age of anomaly 5. J. Geophys. Res. 81:1505-1512

Needham, H.D., Francheteau, J. (1974) Some characteristics of the rift valley in the Atlantic Ocean near 36° 48' north. Earth Planet. Sci. Lett. 22:29-43

Palmason, G. (1973) Kinematics and heat flow in a volcanic rift zone, with application to Iceland. Geophys. J. R. Astron. Soc. 33:451-481

Ross, J.G., Mussett, A.E. (1976) 40Arj3 9Ar dates for spreading rates in eastern Iceland. Nature 259:36-38

Saemundsson, K. (1967) Vulkanismus und Tektonik des Hengili-Gebietes in SiidwestLisland. Acta Nat. lsi. II (7), 195 pp.

Tapponnier, P., Francheteau, J. (1978) Necking of the lithosphere and the mechanics of slowly accreting plate boundaries. J. Geophys. Res. 83:3955-3970

Walker, G.P.L. (1959) Geology of the Reydarfjordur area, eastern Iceland. Q. J. Geol. Soc. London 114:367-391

Walker, G.P.L. (1960) Zeolite zones and dyke distribution in relation to the structure of the basalts in eastern Iceland. J. Geol. 68:515-528

Walker, G.P.L. (1974) The structure of eastern Iceland. In: Geodynamics of Iceland and the North Atlantic Area, L. Kristjansson, ed.: pp.177-188. Dordrecht: Reidel

Watkins, N.D., Walker, G.P.L. (1977) Magnetostratigraphy of eastern Iceland. Am. J. Sci. 227:513-584