SUMMARY

In order to clarify processes of an early stage of compaction of unlithified sediments, we conducted SEM observation of microtexture and magnetic fabric analyses of nannofossil ooze, which was collected from Hole 1074A, on the eastern flank of the Mid-Atlantic Ridge, during ODP Leg 174B. We are able to make the following observations:

1. SEM observation shows that nannofossils and planktonic foraminifers in the sediments are well preserved and that void space in the unlithified sediments is formed by an assemblage of microfossils consisting of a stairstep structure of nannofossils and aggregation of foraminifers.
2. Although the number of spine-shaped fragments of nannofossils is small (<5% at most), it tends to increase with depth. This is probably due to weak compaction by self-loading.
3. AMS results, however, provide little obvious information about deformation of the sediments. These results are consistent with those of onboard MST measurements.