Pre(umbriun Resenr(h

Official Journal of the Subcommission on Precambrian Stratigraphy of the International Union of Geological Sciences

Editor-in-Chief

Co -Editor

Founding Editors

B. Nagy (Tucson, AZ, U.S.A.)

A. KrOner (Mainz, F.R.G.)

B. Nagy (Tucson, AZ, U.S.A.) D.A. Pretorius (Johannesburg, S. Africa) J.G. Ramsay (ZiJrich, Switzerland) K. Rankama (Helsinki, Finland)

Associate Editors C.R. Anhaeusser (Johannesburg, S. Africa) N.T. Arndt (Mainz, F.R.G.) F. Barker (Anchorage, AK, U.S.A.) M.J. Bickle (Cambridge, Gt. Britain) J.C. Briden (Leeds, Gt. Britain) D. Bridgwater (Copenhagen, Denmark) N. Clauer (Strasbourg, France) P. Cloud (Santa Barbara, CA, U.S.A.) W. Compston (Canberra, A.C.T., Australia) K.C. Condie (Socorro, NM, U.S.A.) J. M. Edmond (Cambridge, MA, U.S.A.) K.A. Eriksson (Blacksburg, VA, U.S.A.) M.A° Etheridge (Canberra, A.C.T., Australia) R. Frietsch (Lulea, Sweden) M.F. Glaessner (Adelaide, S.A., Australia) A.M. Goodwin (Toronto, Ont, Canada) G.A. Gross (Ottawa, Ont., Canada) J.M. Hayes (Bloomington, IN, U.S.A.) P.F. Hoffman (Ottawa, Ont., Canada) D.M. Hunten (Tucson, AZ, U.S.A.) D.R. Hunter (Pietermaritzburg, S. Africa) B.-M. Jahn (Rennes, France) H. James (Port Townsend, WA, U.S.A.) C. Klein (Albuquerque, NM, U.S.A.)

A.H. Knoll (Cambridge, MA, U.S.A.) M. Lelubre (Toulouse, France) L. Margulis (Boston, MA, U.S.A.) H. Martin (G~ttingen, F.R.G.) M.W. McEIhinny (Canberra, A.C.T., Australia) W.E.L. Minter (Rondebosch, S. Africa) S. Moorbath (Oxford, Gt. Britain) K. Naha (Kharagpur, W. Bengal, India) K.H. Nealson (Milwaukee, WI, U.S.A.) H.D. Pflug (Giessen, F.R.G.) M. Schidlowski (Mainz, F.R.G.) J.W. Schopf (Los Angeles, CA, U.S.A.) S.M.F. Sheppard (Vandoeuvre, France) S.B. Smithson (Laramie, WY, U.S.A.) R.L. Stanton (Armidale, N.S.W., Australia) R.H. Steiger (ZiJrich, Switzerland) M. Walter (Canberra, A.C.T., Australia) L.E. Weiss (Berkeley, CA, U.S.A.) P.F. Williams iFredericton, N.B., Canada) J.F. Wilson (Harare, Zimbabwe) B.F. Windley (Leicester, Gt. Britain) G.M. Young (London, Ont., Canada) J. Zumberge (Tulsa, OK, U.S.A.)

V O L . 32 (1986)

E L S E V I E R , A M S T E R D A M - O X F O R D - N E W Y O R K - T O K Y O