I solve boundary-value problems for an idealized thrust block moving over a detachment surface and ramp, and produce theoretical bed-duplication folds in the thrust block that closely resemble the Powell Valley anticline in the southern Appalachian Mountains. The anticline is narrow and rounded if the translation is small, and broad and flat-topped if the translation is large. The limbs of the anticline are symmetric if drag is zero. Drag along the ramp part of the detachment surface can explain the asymmetry of dips of the two limbs of the Powell Valley anticline, particularly if drag between relatively competent rocks in opposition at the ramp causes an initial anticline to form as the thrust block begins to move, and then drag reduces markedly as relatively soft shales at the base of the block were thrust over competent rocks in the ramp.
It is recognized that the ecology of planktonic foraminiferal assemblages provides information about the chemical and physical properties of the water in which they live. Their areal and vertical distributions in the water column and in deep-sea sediments may be used to derive oceanographic and climatic models of Recent and past oceans.
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.
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.
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.
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.