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Upper-Miocene submarine volcanism in the strait of sicily
458
D. Submarine Geology and Geophysics
OLR (1983) 30 (6)
the state of stress dominated by the sediment load. It is found that 'aging of passive margins alone does not make them more susceptible to initiation of subduction.' Inst. of Earth Sci., Univ. of Utrecht, Budapestlaan 3584 CD, Utrecht, Netherlands. (bas)
and tectonic evolution are considered, an explanation 'for the scarcity of Early Proterozoic, subduction-related magmatism' emerges. Dept. of Geol. Sci., McGill Univ., Montreal, Quebec H3A 2A7, Canada. (bas)
83:3380 Crawford, A.R., 1982. The Pangaean paradox: where is it? J. Petrol. Geol., 5(2):149-160.
83:3383 Lehner, F.K. and V.C. Li, 1982. Large-scale characteristics of plate boundary deformations related to the post-seismic readjustment of a thin asthenosphere. Geophys Jl R. astr. Soc., 71(3): 775-792.
'Once it is appreciated that the present pattern of the continents and oceans, which is probably nonrandom, is essentially similar to that of a Pangaea which covers all of the Earth except in respect of continental propinquity, it seems possible that the Pangaea thought to have existed from about 1,000 Ma to about 200 Ma may in fact be the original [almost total] crustal distribution but on a smaller Earth.' A post-Pangaean, persistent, exponentiallyincreasing expansion is thought to explain events better than Embleton and Schmidt's (1979) prePangaean expansionary pulse. Geocentric angle data for the period 1000-200 Ma 'may be illusory,' or indicative of 'some inner disturbance.' Dept. of Geol., Univ. of Canterbury, Christchurch 1, New Zealand. (fcs) 83:3381 Geogdzhaev, V.O. and A.E. Osokin, 1981/82. Rigid plastic underthrust of litbospheric plates. Phys. solid Earth (a translation of Fiz. Zemli), 17(11): 870-873.
Large-scale response of an elastic lithosphere, riding on a 'thin' viscoelastic asthenosphere, to periodically occurring ruptures at a transform or subduction-type plate boundary is described approximately by appropriate limit cycle solutions for a plate/foundation model introduced by Rice. Cyclic behavior of thickness-averaged displacements, strains and strain rates, their decay away from the plate boundary, and a resolution into coseismic and post-seismic alterations are obtained; dependence on repeat time and characteristic relaxation time is investigated. Results suggest viscosity stratification affects post-seismic rebound when earthquake repeat times exceed relevant relaxation times by at least one order of magnitude. Div. of Engrg., Brown Univ., Providence, R.I., USA. 83:3384 McKenzie, Dan, 1982. The evolution of propagating rifts. Nature, Lond., 300(5894):740-742.
A mechanical model of lithospheric plate underthrusting considers plastic deformation in the contact zone between the over- and under-thrust plates, operates 'within the framework of rigid plastic' behavior, and determines the 'velocity and stress fields in the deformation focus' and the inter-plate contact pressure. Tectonic problems are not covered. Inst. of Appl. Phys., Moscow, USSR. (bas)
Ridge propagation leads to a characteristic pattern of magnetic anomalies offset by discontinuities (pseudofaults). The geometry of pseudofaults, magnetic anomalies and the failed rift can be determined using velocity triangles and the concept of stability. Bullard Lab., Dept. of Earth Sci., Madingiey Rise, Madingley Rd., Cambridge CB3 0EZ, UK.
83:3382 Hynes, A., 1982. Stability of the oceanic tectosphere:
D280. Volcanism, magmatism
a model for Early Proterozoic intercratonic orogeny. Earth planet. Sci. Letts, 61(2):333-345. Modem oceanic tectosphere stability is related to the resistance to subduction as a function of flexural rigidity, subduction zone shear resistance and negative buoyancy and, therefore, thicknesses of the effective elastic layer and the tectosphere. In the model, the tectosphere's stability decreases with age, with modern tectosphere 'spontaneously subducting' at an age of 200 Ma; in contrast, Proterozoic tectosphere subducts at an age of 75 Ma. When implications of the subduction for magma genesis
83:3385 Beccaluva, L., P. Colantoni, P. Di Girolamo and C. Savelli, 1981. Upper-Miocene submarine volcanism in the Strelt of Sicily. Bull. volcan., 44(3): 573-581. Ist. di Petrografia dell'Univ., Parma, Italy. 83:3386 Brousse, R., H. Bizouard and N. Metrich, 1981. IFatal (Azores) and Rapa (Austral Islands): alkali similarities evolved under anhydmm conditluns.I Bull. volcan., 44(3):393-410. (In French, English
D. Submarine Geology and Geophysics
OLR (1983) 30 (6)
the state of stress dominated by the sediment load. It is found that 'aging of passive margins alone does not make them more susceptible to initiation of subduction.' Inst. of Earth Sci., Univ. of Utrecht, Budapestlaan 3584 CD, Utrecht, Netherlands. (bas)
and tectonic evolution are considered, an explanation 'for the scarcity of Early Proterozoic, subduction-related magmatism' emerges. Dept. of Geol. Sci., McGill Univ., Montreal, Quebec H3A 2A7, Canada. (bas)
83:3380 Crawford, A.R., 1982. The Pangaean paradox: where is it? J. Petrol. Geol., 5(2):149-160.
83:3383 Lehner, F.K. and V.C. Li, 1982. Large-scale characteristics of plate boundary deformations related to the post-seismic readjustment of a thin asthenosphere. Geophys Jl R. astr. Soc., 71(3): 775-792.
'Once it is appreciated that the present pattern of the continents and oceans, which is probably nonrandom, is essentially similar to that of a Pangaea which covers all of the Earth except in respect of continental propinquity, it seems possible that the Pangaea thought to have existed from about 1,000 Ma to about 200 Ma may in fact be the original [almost total] crustal distribution but on a smaller Earth.' A post-Pangaean, persistent, exponentiallyincreasing expansion is thought to explain events better than Embleton and Schmidt's (1979) prePangaean expansionary pulse. Geocentric angle data for the period 1000-200 Ma 'may be illusory,' or indicative of 'some inner disturbance.' Dept. of Geol., Univ. of Canterbury, Christchurch 1, New Zealand. (fcs) 83:3381 Geogdzhaev, V.O. and A.E. Osokin, 1981/82. Rigid plastic underthrust of litbospheric plates. Phys. solid Earth (a translation of Fiz. Zemli), 17(11): 870-873.
Large-scale response of an elastic lithosphere, riding on a 'thin' viscoelastic asthenosphere, to periodically occurring ruptures at a transform or subduction-type plate boundary is described approximately by appropriate limit cycle solutions for a plate/foundation model introduced by Rice. Cyclic behavior of thickness-averaged displacements, strains and strain rates, their decay away from the plate boundary, and a resolution into coseismic and post-seismic alterations are obtained; dependence on repeat time and characteristic relaxation time is investigated. Results suggest viscosity stratification affects post-seismic rebound when earthquake repeat times exceed relevant relaxation times by at least one order of magnitude. Div. of Engrg., Brown Univ., Providence, R.I., USA. 83:3384 McKenzie, Dan, 1982. The evolution of propagating rifts. Nature, Lond., 300(5894):740-742.
A mechanical model of lithospheric plate underthrusting considers plastic deformation in the contact zone between the over- and under-thrust plates, operates 'within the framework of rigid plastic' behavior, and determines the 'velocity and stress fields in the deformation focus' and the inter-plate contact pressure. Tectonic problems are not covered. Inst. of Appl. Phys., Moscow, USSR. (bas)
Ridge propagation leads to a characteristic pattern of magnetic anomalies offset by discontinuities (pseudofaults). The geometry of pseudofaults, magnetic anomalies and the failed rift can be determined using velocity triangles and the concept of stability. Bullard Lab., Dept. of Earth Sci., Madingiey Rise, Madingley Rd., Cambridge CB3 0EZ, UK.
83:3382 Hynes, A., 1982. Stability of the oceanic tectosphere:
D280. Volcanism, magmatism
a model for Early Proterozoic intercratonic orogeny. Earth planet. Sci. Letts, 61(2):333-345. Modem oceanic tectosphere stability is related to the resistance to subduction as a function of flexural rigidity, subduction zone shear resistance and negative buoyancy and, therefore, thicknesses of the effective elastic layer and the tectosphere. In the model, the tectosphere's stability decreases with age, with modern tectosphere 'spontaneously subducting' at an age of 200 Ma; in contrast, Proterozoic tectosphere subducts at an age of 75 Ma. When implications of the subduction for magma genesis
83:3385 Beccaluva, L., P. Colantoni, P. Di Girolamo and C. Savelli, 1981. Upper-Miocene submarine volcanism in the Strelt of Sicily. Bull. volcan., 44(3): 573-581. Ist. di Petrografia dell'Univ., Parma, Italy. 83:3386 Brousse, R., H. Bizouard and N. Metrich, 1981. IFatal (Azores) and Rapa (Austral Islands): alkali similarities evolved under anhydmm conditluns.I Bull. volcan., 44(3):393-410. (In French, English