OLR (1981 ) 28 (12) D. Submarine Geology and Geophysics 879

have ~mportant implications for mantle geochemical structure. CSIRO Div. of Mineralogy, P.O. Box 136, North Ryde, NSW 2113, Australia.

81:6627 Yanagi, Takeru, 1981. Alternative magmatic pro-

cesses of continental growth in an island arc. Mere. Fac. Sci. Kyushu Univ., 24(3):189-206.

Geological and geophysical observations of Miocene igneous processes in Japan show both calc-alkalic volcanism and emplacement of granitic plutons. Magma supply rates and crustal thickness determine whether batch fractionation of parental magmas occurs: if so, a volcanic arc composed of both volcanics and granitic plutons forms; if not, the magma moves horizontally accumulating behind an aseismic front, forming an outer arc composed of granitic plutons. (bas)

D290. Crust, mantle, core

81:6628 Anderson, D.L., 1981. Hotspots, basalts, and the

evolution of the mantle. Science, 213(4503): 82-89.

Oceanic island and ridge, and continental basalt trace element concentrations are found comple- mentary, controlled by garnet and clinopyroxene. MORB's are thought to evolve from eclogite cu- mulates, and continental and island basalts from garnet peridotite with secondary enrichment; their combined volume is believed to extend down to the 670 km discontinuity. Seismological Lab., California Inst. of Tech., Pasadena, Calif. 91125, USA. (bas)

81:6629 Cox, C.S., 1981. On the electrical conductivity of the

oceanic lithosphere. Phys. Earth planet. Interiors, 25(3): 196-201.

Generalized estimates of conductivity distributions are given. Methods used to obtain these values are discussed: MT which gives impedance as a function of frequency; measurement of the ocean-floor quasi-static electric field; and using controlled source EM which can register conductivities as low as 0.004 S m ~. Scripps Inst. of Oceanography, La Jolla, Calif. 92093, USA. (bas)

81:6630 East Pacific Rise Study Group, 1981. Crustal

processes of the Mid-Ocean Ridge. Science, 213(4503):31-40.

Results from numerous mid-ocean ridge studies are synthesized focusing on the nature of the magma

chamber system, associated crustal dynamics, ocean chemistry, and the origin of rifted central axis sulfide deposits. Ocean and ophiolite characteristics inves- tigated were surface volcanism, heat budget, mag- netic properties, isostatic response, hydrothermal circulation, crustal structure and subbottom pro- cesses, and crustal composition. Includes 98 ref- erences. R.D. Ballard: Ocean Engrg. Dept., WHOI, Woods Hole, Mass. 02543, USA. (bas)

81:6631 Filloux, J.H., 1981. Magnetotelluric exploration of

the North Pacific: progress report and prelimi- nary soundings near a spreading ridge. Phys. Earth planet. Interiors, 25(3):187-195.

Six MT seafloor experiments near 12°N on the Pacific Rise crest in crust 0.8 and 2.7 m.y. old were carried out to determine the method's applicability for marine geophysics. Results are consistent with plate tectonic interpretations and are similar to those for the MAR beneath NE Iceland. This method coupled with natural-source seismology could offer a 15-30 km effective depth range. Scripps Inst. of Oceanography, La Jolla, Calif. 92093, USA. (bas)

81:6632 Malovitskiy, Ya.P. and L.A. Yesina, 1980. Deep-

seated structure of the Mediterranean Sea ac- cording to geophysical data. Geotectonics (a translation of Geotektonika), 14(4):297-302.

The Alpine fold belt, platform regions and deep- water basins are the reference associations for the 3 types of crustal structure recognized; tectonic im- plications are considered. Crust basal relief is diagrammed. P.P. Shirshov Inst. of Oceanology, USSR Acad. of Sci., Gelendzhik, USSR. (sir)

81:6633 Parkinson, W.D. and D.C. Tozer (eds.), 1979/81.

Electrical conductivity and the characteristics of the asthenosphere. Symposium, XVII IUGG General Assembly, Canberra, A.C.T., Australia, December 3-15, 1979. Special issue. Phys. Earth planet. Interiors, 25(3): 187-296; 13 papers.

'Electromagnetic induction studies now look des- tined to take their place beside geodesy and seismology as a valuable independent method for probing the Earth's upper mantle.' In addition to papers covering general mechanical and electrical properties of the crust and asthenosphere, regional studies cover the North Pacific, Australia, Pamir- Himalaya, Bowen Basin, India, Brazil and Germany. (fcs)