CONCLUSIONS

This study has demonstrated the potential value of paleomagnetic, rock magnetic, and geological investigations in providing the essential link between remanence magnetization, rock magnetic property variations, and magnetic mineralogy. Based on rock magnetic results obtained during our postcruise study of Leg 183 cores, we can draw the following conclusions:

  1. The majority of subaerial basalt samples from Sites 1136 (119 Ma), 1137 (108 Ma), 1138 (100 Ma), 1141 (95 Ma), and 1142 (95 Ma) underwent deuteric high-temperature oxidation, which is responsible for the high Curie temperature. These subaerial basalts are probably good paleomagnetic recorders that can preserve original and stable magnetic remanences.
  2. The rock magnetically inferred fine grain size indicates a rapid cooling environment for the pillow lavas of Site 1140 (34 Ma). The generally good magnetic stability exhibited by the titanomagnetite-bearing rocks suggests that the stable inclinations identified from these submarine samples are useful for future tectonic studies.
  3. Although rocks at Site 1142 were listed as possible pillow basalt, rock magnetic data suggest they are probably same as their counterpart at Site 1141, erupted in a subaerial environment. Their normal magnetic polarity supports the inference that the ChRM isolated from the 95-Ma rocks were acquired during the Cretaceous Normal Superchron (121-83 Ma).
  4. Basalt flows at Site 1139 underwent low-temperature oxidation. Substantial alteration at this site has subsequently taken place and may have reset the original magnetization.

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