The magnetic polarity stratigraphy at Site 907 obtained from the shipboard pass-through magnetometer and from discrete samples is readily interpretable back to the onset of the Gilbert Chron (5.89 Ma). From this level to the base of the section at ~14 Ma, the interpretation is corroborated by silicoflagellate datums with predictable correlation to polarity chrons. The resulting magnetostratigraphic interpretation differs from those proposed in the Leg 151 (Hole 907A) and 162 (Holes 907B and 907C) Initial Reports volumes. An important hiatus in the 7-10 Ma interval at Site 907 caused sedimentation to slow or cease for ~2.7 m.y. We have revised the shipboard correlation among the three holes at Site 907, resulting in a new composite section splice and recalculation of composite depths.
For Site 985, magnetostratigraphic interpretation is possible down to ~150 meters below seafloor (mbsf) (C3An/C3Ar) at ~6 Ma. There are no useful biostratigraphic datums from Site 985 to support this interpretation; however, the interpretation is supported by the correlation of Sites 985 and 907 using natural gamma data from the shipboard multisensor track. Below ~150 mbsf at Site 985, drilling-related deformation at the onset of extended core barrel drilling precluded magnetostratigraphic interpretation.
1Raymo, M.E.,
Jansen, E., Blum, P., and Herbert, T.D. (Eds.), 1999. Proc.
ODP, Sci. Results, 162: College Station, TX (Ocean Drilling
Program).
2Department
of Geology, University of
Florida, Gainesville, FL 32611-2120, U.S.A. Channell: jetc@nersp.nerdc.ufl.edu
3Department
of Geology, University of
Copenhagen, DK-1350 Copenhagen, Denmark.
4Department
of Geodesy and Geomatics
Engineering, University of New Bruns-wick, Fredericton, NB E3B
5A3, Canada.
5Laboratoire
des Sciences du Climat et de
l'Environnement, CNRS-CEA, Avenue de la Terrasse, 91198
Gif-sur-Yvette, France.
Date
of initial receipt: 10 September 1997
Date of acceptance: 25 March 1998
Ms 162SR-036