The Middle Proterozoic Jacobsville Sandstone, located on the upper peninsula, Michigan, is the youngest rift- related sedimentary unit in the 1.1 Ga Midcontinent rift. Although outcrops of the Jacobsville Sandstone along the Lake Superior shoreline and in river gorges are well studied, these outcrops represent stratigraphically only the upper 300-400 feet of the estimated 9,000 feet thick Jacobsville Sandstone. I used drill cores and newly-studied outcrop samples; 1) to characterize stratigraphically continuous sections; 2) to compare the Jacobsville Sandstone in subsurface with the Jacobsville Sandstone in outcrop; 3) to identify lateral and vertical variations in texture and petrographic composition within the Jacobsville Sandstone; and 4) to determine petrographic provenance of the Jacobsville Sandstone.
Cambrian sedimentation of the Rome trough in eastern Kentucky was studied using 85 wells supplemented by available cuttings and cores. Most conclusions are based on cross sections, isopach and structure maps, and the environmental interpretation of geophysical logs. Thin section petrology played a supplementary role.
Mapping of the Wayaro quadrangle (680 sq kms; scale 1:50,000) revealed that the Bela Ophiolites were thrust upon a sedimentary melange (Kanar Melange) which was deposited in the Paleocene on the Sembar Formation of Cretaceous age.
Detailed mineralogic and chemical analyses of well cuttings of Tertiary sediments from two wells, Uruan-1 and Uda-1, on the eastern flank of the Niger delta, have been made in an attempt to investigate clay mineral burial diagenesis.
The principal objective of this study was to develop a battery of methodologies for the analysis of texture, grain packing and pore geometry in sands and sandstones. The methodologies developed include: (1) the 'roller micrometer', a machine which sizes grains by their smallest dimension, S; (2) plots of the joint I:S size and S/I form distributions (I is the intermediate grain dimension determined by sieving); (3) a sorting comparator for the visual estimation of sorting in thin sections; (4) 'packing efficiency', the ratio of minimum compactional to depositional porosity; (5) 'floating index', the proportion of grains lacking intergranular contacts; (6) correction of measurement errors in standard thin section packing analyses; (7) transformation, via digitization, of plain sections of samples into matrices of binary (rock vs pore) numbers; and (8) computer processing of the rock-pore matrices using the Fortran IV program PORESTAT which measures numerous parameters including porosity, specific pore surface area, pore size distribution, pore tortuosity, pore orientation, and periodic repetitions in the pore pattern.