stratigraphic significance. This is especially true of persistent reflectors 

 that can be traced over a substantial area. 



152. The process of record analysis is largely one of separating valid 

 from spurious reflectors, correlating the more persistent reflectors from line 

 to line, and projecting reflector trends between gaps in the trace or where 

 the reflector trace is obscured by spurious reflections. The first step is to 

 delineate and mark the trace of the true reflectors on copies or overlays of 

 each line in turn, using the original records, as mentioned above, for making 

 the interpretation. Having done this, correlations are made wherever possible 

 between the same reflector surface on adjacent lines so that the areal extent 

 of each rock and sediment body can be determined. If core data are available 

 at this point, they can be of great value in making reliable correlations. 



153. Various procedures can be used to organize the seismic reflection 

 data into a coherent system that can depict the stratigraphic framework. The 

 procedure described here was developed during the course of the ICONS program. 

 In this procedure, three elements are used: primary reflectors, secondary 

 reflectors, and reflection units (Figure 13). Primary reflectors (or hori- 

 zons) are those that persist over a substantial area and can be traced from 

 line to line. Primary reflectors are given an identifying letter, number, or 

 name. Secondary reflectors are much less extensive than primary reflectors 

 and often may be related to internal bedding features. They are delineated 

 and marked but not usually given an identification except in detailed studies 

 of a relatively small area. Areas between primary reflectors are called 

 reflection units and are assumed to be stratigraphically definable elements 

 (Figure 13). These units are usually given an identifying letter, number, or 

 name and correlated throughout the area of their occurrence. 



Core Logging and Sample Analysis 



154. During the field data collection phase of an exploration program, 

 a preliminary analysis of the cores and samples from the cores is made on a 

 day-to-day basis to obtain information for making advantageous modifications 

 to the survey plan. In addition, when the specific site surveys of high 

 potential borrow sources are undertaken immediately following the general sur- 

 vey, the preliminary analysis must suffice for selection of these sites, and 

 needs to be as complete and accurate as possible. 



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