778 D. Submarine Geology and Geophysics OLR (1982) 29 (12)

Kamchatka). Geotectonics (a translation of Geo- tektonika), 15(4):363-374. O. Yu. Schmidt Inst. of Terrest. Phys., USSR.

82:6106 Singh, S.K., J.M. Espindola, J. Yamamoto and J.

Havskov, 1982. Seismic potential of the Aca- pnico-San Marcos region along the Mexican snbdnction zone. Geophys. Res. Letts, 9(6):633- 636. Inst. de Ingen, U.N.A.M., C.U. Mexico 04510, D.F.

82:6107 Sviridov, N.I., 1981. Deformations of stratification in

the sedimentary section of the Baltic Sea floor. Geotectonics (a translation of Geotektonika), 15(4):307-317. P.P. Shirshov Inst. of Oceanol., USSR Acad. of Sci., Kaliningrad, USSR.

82:6108 Swanson, M.T., 1982. Preliminary model for an early

transform history in central Atlantic rifting. Geology, geol. Soc. Am., 10(6):317-320.

A coherent tectonic model accounts for eastern North America's highly variable Triassic-Jurassic structural developments, both geological and pa- leomagnetic, by incorporating 'a dextral and sinistral shear phase along an arcuate transform zone' which was the incipient North American/African plate boundary. This early transform history suggests a wide shear zone developed during counterclockwise (Late Permian-Middle Triassic) and clockwise (Mid- dle Jurassic) rotations (Saharan pole) of Africa and South America relative to North America. Com- bined with conventional Mesozoic Atlantic rifting theory, the model accounts for some previously unexplained structural patterns, SUNY, 1400 Wash- ington Ave., Albany, NY 12222, USA. (slr)

82:6109 Ueda, Yoshio, 1982. Geomagnetic anomaly analysis

of the scamounts D a l i t i - ~ and Katori, off Kasimanada, southern part of the Japan Trench. With special reference to the subduction process of seamount Daiiti-Kashima. Special number. Data Rept hydrogr. Obsns, Tokyo, 17:13-30. (In Japanese, English summary.) Maritime Safety Agency, Tokyo, Japan.

D250. Plate and global tectonics

82:6110 Anderson, D.L., 1982. Hotspots, polar wander,

Mesozoic convection and the geoid. Nature, Lond., 297(5865):391-393.

Widespread uplift, magmatism, breakup and initial dispersal of Pangea apparently occurred while the continents were centrally located with respect to the present geoid anomaly. Subsequent motions of Atlantic bordering plates were largely directed away from the anomaly, suggesting that the residual geoid high, hotspots, the distribution of continents during the Late Palaeozoic-Early Mesozoic and their uplift and subsequent dispersal and subsidence are all related. The major global geoid highs, regions of extensive Cretaceous volcanism, may be former sites of continental aggregations and mantle insulation. The pent-up heat causes rifts and hotspots, resulting in uplift, magmatism, fragmentation and dispersal of the continents and subsequent formation of plateaus, aseismic ridges and seamount chains which cause a global rise in sea level. Upper mantle convection caused by such lateral temperature gradients is intrinsically episodic. Seismol. Lab., Calif. Inst. of Tech., Pasadena, Calif. 91125, USA.

82:6111 Beaumont, C., C.E. Keen and R. Boutilier, 1982. A

comparison of foreland and rift margin sedimen- tary basins. Phil. Trans. R. Soc., (A)305(1489): 295-317.

Archetypal models for the tectonic subsidence of foreland and rift margin sedimentary basins are proposed and developed with regard to lithospheric rheology, lateral changes in lithospheric properties, and response to sediment and water loading. Pre- dicted characteristics of each basin type are in agreement with observations. The superposition of foreland and rifted margin basins that can occur with ocean closure results in a complex overall stratigraphy, and any analysis of subsidence history must distinguish and consider all factors in the tectonic environment. Dept. of Oceanogr., Dalhousie Univ., Halifax, N.S. B3H 4JI, Canada. (dlf)

82:6112 Bott, M.H.P., 1982. Origin of the lithospheric tension

causing basin formation. Phil. Trans. R. Soc., (A)305(1489):319-324.

Most intraplate fault-controlled basin formation occurs in response to horizontal deviatoric tension most likely originating from the plate boundary forces acting at trenches or as a result of isostaticaUy compensated uplift (e.g. East Africa). Tension produced by both mechanisms is greatest in high heat-flow regions where the upper elastic lithosphere is thinned and weakened. Particularly widespread tension in the continental lithosphere occurs when subduction takes place on opposite sides of a large continental mass such as Pangea in the Early