Abstract: Magnitudes of Early Diagenetic Compaction in the Onondaga Limestone of Central and Eastern New York

Richard H. Lindemann

Stylioline conch deformation is diagnostic of mechanical compaction within the Middle and Upper Devonian marine strata that contain them. The quantification of deformational severity, which involves determination of the ratio between the vertical and horizontal dimensions of the conch in transverse section, provides a minimal approximation of the magnitude of compactive dewatering as well as some insight into the timing of initial cementation.

Stylioline deformation was measured in samples of the Onondaga Limestone from localities throughout eastern and central New York to assess trends in, and magnitudes of, compaction. It was found that grainstones and packstones of the Edgecliff Member throughout the region, as well as the upper Moorehouse Member in the east, experienced minimal compaction. In general, mud-stones and wackestones experienced 10-30% compaction while argillaceous mudstones of the Nedrow Member fall in the 40-60% range. Though these figures are low in comparison to the 85+% compaction calculated from styliolines in the Marcellus Formation's black shales, it is concluded that significant quantities of primary pore fluid were expelled from the Onondaga's fine-grained facies early in the formation's diagenetic istory.

AAPG Search and Discovery Article #90954©1995 AAPG Eastern Section, Schenectady, New York