874 D: Submarine Geology and Geophysics OLR (198t) 28 (t2)

The means and significance of obtaining geodetic measurements at sea and on land are compared. Satellite controls, and surface height and geopo- tential measurements over the oceans are discussed. A means to locate seafloor instruments on a precise coordinate system is still needed. Cavendish Lab., Madingley Rd., Cambridge C B 3 0 H E UK. (hbf)

81:6586 Hodder, B.M., 1981. Geomagaetic secular variation

since 1901. Geophys. Jl R. astr. Soc~ 65(3):763- 776 + 1 microfiche. Inst. of Geol. Sci., Murchi- son House, West Mains Rd., Edinburgh EH9 3LA, Scotland.

81:6587 Sumitomo, Norihiko, 1981. Geomal lR~ secular

variation anomalies In relUlea to the recent crustal movement in the ~ rel~on of Jq~im. Bull. Disaster Prevent. Res. Inst., Kyoto Univ., 30(4)(274):9% 130.

Results of 2 geomagnetic surveys (over 100 sites) show a characteristic and systematic pattern of local secular-variation anomalies. It is suggested that these may arise from horizontal compression associated with motions of the Pacific and Philippine Sea plates. (has)

D210. Heat flow

81:6588 Galson, D.A. and R.P. Von Herzen, 1981. A heat

flow sm'vey on mmmaly MIJ sm,th ef tim: Ilenmmla Rise. Earth planet. Sci. Letts, 53(3):296-306.

Heat flow measurements on old (109 Ma) Atlantic crust are compared with plate and boundary layer lithosphere (oceanic) cooling models; difference between the predictions of the two models is on the order of actual measurement uncertainty, disallow- ing model discrimination on the basis of surface heat flow data alone. Dept. of Earth Sci., Univ. of Cambridge, Downing St., Cambridge CB2 3EQ, UK. (sir)

D240. L m ~ or regional tectonics

8 1 : 6 ~ 9 Allis,

tt Soc. Am., 9(7):303-307.

The transition from oceanic to continental crust is the suggested cause of underthrusting along the

Alpine Fault south of Mt. Cook. This is evidenced by high heat flow and a crustal root with an isostatic anomaly. North of Mr. Cook, uplift and erosion of the Pacific Plate continental crdSt accommodate the crustal shortening. Geophys. Div., DSIR, Private Bag, Taupo, New Zealand. (bas)

81:6590 Bahat, Dov, 1981. Certain ~ aspects in

comparative ~ ~ with a ~ a i reference to the ~ Rift. Geol. Mag., 118(3): 27i-280 + 1 plate.

Unique features of the Baikal Rift system are explained in a 2-phase mechanical model involving upward stress (causing fracturing) followed by horizontal forces (causing tectonic displacements). It is suggested that the initiation of rifting may be in response to local upper mantle upwelling rather than regional crustal stresses, Bifurcation patterns in the Rhine grahen, Dead Sea and Baikal are compared and related to the model. Includes photos of fracture branching of glass bottles. Dept. of Geol. and MineraL, Ben Gurion Univ. of the Negev, Beer Sheva, Israel (bas)

81:6591 Bogdanov, Yu.B., R.B. Bylinskiy, V.A. Glebovitskiy

and A.V. Dolivo,Dobrovol'skiy, 1980. The main White Sea suture. Geotectonics (a translation of Geotektonika), 14(3):188-193. Inst. of Precam, brian Geol. and Geochronology, USSR Acad. of Sei., Leningrad, USSR.

81:6592 Christie, R.L. et al., 1981. G ~ e v i ~ ~ t

major displacement in file Nares Strait. Nature, Lond., 291(58 i5):478-480.

Seven independent bedrock geology ,markers' set a limit of 0-25 km maximum net left taterai dis- placement of Greenland along Nares Strait; other reconstructions have proposed a 150-400 km dis- placement, which 'approximates the distance sepa- rating the present continental shelves.' A new mechanism for the evolution o f Baffin Bay oceanic crust is needed to agree with the newly proposed displacement. Geol. Survey of Canada, Calgary, Canada T2L 2A7. (bas)

81:6593 Hanug, V. and J. Van6k, 1981. Plate tectonic

~ of deep ~ ~ e e o the ~ New ~ ~ n zo,,es.

Tectonophysics, 75(3/4) :T19~8.

Seismicity geometry and Wa~fi,Benioff zone mor- phology suggest the earthquakes are due to the deep