ABSTRACT

The Tuscarora Sandstone is generally tightly cemented with secondary quartz but locally the cement is irregularly distributed. Some beds have a banded appearance caused by alternating layers of tightly cemented and poorly cemented zones. Argillaceous material occurs in the poorly cemented bands and apparently inhibited the development of normal secondary growths. A lattice pattern results where cemented bands formed at right angles to bedding as well as parallel to bedding. The transverse bands may have been controlled by fractures inasmuch as they are parallel to fractures in the formatior. Uncemented lenses occur in some beds which are otherwise tightly cemented. Gas pockets apparently prevented complete cementation in these beds. Considerable primary clay was replaced by secondary uartz because clay is present in the uncemented lenses but is lacking in the cemented rock enclosing the lenses. Thick clay coatings on grains may prevent growth of secondary quartz. If pressure solution does not occur, considerable porosity is present where the grains are coated with clay.