Page 69 - Petrophysics
P. 69
SEDIMENTARY GEOLOGY 43
,SEDIMENTS
e H E L W QLOSVNCLINE d
Figure 2.3. Accumulation of graywacke-type sediments in a geosyncline adjacent to
a land mass of moderate relief [ll].
Figure 2.4. Idealized conditions that lead to deposition of arkose-type sediments.
Steep land relief results in incomplete chemical weathm'ng that yielas arkose-type
sediments I1 I].
size variation. Reactive clays and unstable minerals such as feldspars
are mixed with other grains and also make up a large portion of the
cementing agents. Variable climatic conditions of the physiographic
area result in periods of deposition of coarse clastics followed by fine
sediments that eventually become the caprocks of reservoirs (Figure 2.4).
