Descriptions of turbidite deposits in the 1960s were based almost wholly on the Bouma (1962) sequence and its variations (Figs. 3-7 and 7-18). Very thick-bedded, massive sandstone and conglomerate lacking the ordered divisions of the Bouma sequence were termed fluxoturbidites (Dzulynsky et al., 1959), grain-flow deposits (Stauffer, 1967) and various other names. These deposits were little understood and their relation to turbidites that are organized into the Bouma sequence was very uncertain. Basin analyses were made chiefly by paleo-current, petrographic, and Bouma-sequence analysis.
The initial deposits of a turbidity current on a basin floor were thought to result in a bed that contained the complete (Ta−e) Bouma sequence (Figs. 3-7, 7-14, and 8-1). As the turbidity current flows basinward, the turbidite deposit becomes progressively finer, thinner, and progressively composed of the higher divisions of the Bouma sequence. The basic nature of this gradual transition has been proven by a number of laboratory experiments (Fig. 3-8). Walker (1967), based on these considerations as well as field experience with ancient turbidite systems, developed the ABC or Proximality Index for basin analysis of turbidite systems (Fig. 8-2). By comparing the percentage of beds beginning with the Bouma T division to the percentage of beds beginning with the Bouma Tb division, it was thought that proximal-distal relations for a group of turbidites or given basin could be determined. Walker (1967) also compared in tabular form the chief characteristics of proximal and distal turbiditedepos (Fig. 8-3).
However, the increasing recognition of major channels on modern
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Modern and Ancient Deep-Sea Fan Sedimentation
This course of modern and ancient deep-sea fan sedimentation provides the framework for understanding the morphology, physiography, geometry, depositional processes and reservoir potential of deep-sea fan deposits. Focus is chiefly on the principles that control fan sedimentation and the resultant morphology of fans deposited in various types of settings. Through the comparison of modern and ancient examples of deep-sea fan sedimentation, the authors hope to increase understanding of the principal characteristics of fans. The course is divided into four parts (1) the Introduction, which covers the organization of the course and history of fan studies, (2) modern deep-sea fan deposits, (3) ancient deep-sea fan deposits, and (4) the synthesis, in which the results of the separate modern and ancient examinations of deep-sea fan deposits are synthesized into models that may be applicable to petroleum exploration.