PART VIII: PRELIMINARY DATA ANALYSIS 



140. As mentioned previously, preliminary analysis of the geophysical 

 and core data is desirable in order to obtain information that can be used for 

 making necessary or advantageous changes in the survey and coring plan as 

 field work progresses. The objective of this part is to discuss techniques of 

 analyzing geophysical and core data for the purpose stated above. A more com- 

 plete and comprehensive formal analysis must wait until a later date when the 

 complete set of geophysical records and cores of the exploration area are 

 available . 



141. The limited time available for field analysis of geophysical data 

 is best devoted to analyses of the seismic reflection records. Fathometer 

 traces need no special interpretation techniques, and side-scan sonar records 

 do not normally contain information crucial to decisions on modifications and 

 additions to the survey and coring plan; therefore, the following discussion 

 is limited to seismic reflection and core data. 



Seismic Reflection Records 



142. Analysis of seismic reflection records is a fairly straightforward 

 process. Reflectors are shown by line traces on the record that are similar 

 to a geologic cross section of the area beneath the tracklines. However, some 

 of these reflector traces are not related to actual reflecting surfaces in the 

 sub-bottom, but are spurious by-products of the seismic reflection method. 

 Much of the analysis involves sorting out the true from the false reflectors 

 and correlating true reflectors from line to line. 



143. Analysis of seismic reflection records involves the handling of 

 strip chart sections of individual tracklines that are as much as 10 m or more 

 in length. A primary requisite for analysis is to obtain sufficient space to 

 lay out enough record at any one time to obtain an overall view of a substan- 

 tial part of the line. This allows the interpreter to better develop the 

 reflector patterns and to sort out spurious reflectors and project trends. In 

 general more space is required than can be found on a desk top or drafting 

 table. A reasonable minimum should be about 5m. A portable table of suffi- 

 cient length made from plywood paneling supported on wooden trestles can 



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