ABSTRACT

The Texas Colorado River delta, which built across Matagorda Bay between 1929 and 1941, was selected for consolidation research. The objectives were to observe structural changes which occur when deltaic sediments undergo primary consolidation, and to correlate these consolidated sedimentary structures with those reported from ancient deltaic environments.

Double cores were collected along a traverse parallel to the main river channel in the southeast lobe of the delta. One core was split lengthwise, described and radiographed. An analogous undisturbed section of the second core was then selected for consolidation.

Consolidation, through vertically compressing the sediments, partially creates new structures or makes poorly visible structures more discernable. It was noted in some cases that convolute laminations and recumbent folding formed after sections containing parallel lamination were consolidated. It was also observed that apparent homogeneous sections after compaction changed structurally to reveal parallel laminations.

Consequently, it should be realized that consolidation will effect unconsolidated sediments and that these changes should be considered when comparing recent and ancient environments.