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Leonard D. Harris

Publications and source records attributed to Leonard D. Harris.

12 recordsLinked to original sources
USGS1976

Thin-skinned tectonics and potential hydrocarbon traps: Illustrated by a seismic profile in the Valley and Ridge province of Tennessee

Seismic data, although limited to a small part of the western half of the Valley and Ridge province in Tennessee, confirm that the structural style is thin-skinned and that there is a fundamental change from west to east in both the total section preserved and the structural complexities that exist in the subsurface. Cambrian to Upper Ordovician rocks in the Valley and Ridge province have been thrust westward over a 4-mile (6.4-km) projection of Cambrian through Mississippian rocks of the Appalachian Plateau. Structure within the plateau projection is characterized by splay anticlines, whereas structure in the Valley and Ridge is dominated by a series of imbricate thrust sheets containing isolated fault-bound masses of Cambrian sandstone and shale. Both splay anticlines and large fault-bound masses of rocks preserved in the subsurface in east Tennessee may be favorable fracture-porosity traps for the accumulation of hydrocarbons.

Tennessee↗
USGS1973

Dolomitization model for Upper Cambrian and Lower Ordovician carbonate rocks in the eastern United States

Existing models for dolomitization emphasize that penecontemporaneous dolomitization can occur in both subtidal and supratidal environments if the necessary chemical and physical factors favorable for the development of magnesium-rich hypersaline waters exist. Holocene shallow-water hypersaline environments that have the potential to produce dolomite without deposition of more soluble evaporite minerals are found in Shark Bay, Australia, and on the Great Bahama Bank. These hypersalinity systems are characterized by near-vertical isosalinity layers of increasing concentration landward from the open ocean and show little or no relationship to bottom topography. I suggest that a similar but larger scale epicontinentalsalinity system covering the Late Cambrian and Early Ordovician carbonate continental shelf produced a broad wedge of subtidally deposited dolomite in the eastern half of the United States from Mexico to Canada. The distribution of limestone and dolomite in this region is closely keyed to the salinity gradient and accounts for the natural progression from a normal marine limestone facies through a transition zone to a highly saline dolomite facies phase. Algal stromatolite mats and domes occupied low-energy niches in both the limestone and dolomite facies, whereas stratiform algal stromatolites were confined to the areas of moderate energy within the dolomite facies.

Journal of Research of the U.S. Geological Survey↗
USGS1971

A lower paleozoic paleoaquifer; the Kingsport Formation and Mascot dolomite of Tennessee and southwest Virginia

The Kingsport Formation (Lower Ordovician) in one section may be composed of two dominant rock types--limestone and medium to coarsely crystalline dolomite--whereas in an adjacent section, most of the formation may be largely composed of breccia. The breccia bodies, which are interpreted to be solution-collapse features, range in width from 30 feet to several hundred feet, in thickness from a few feet to more than 200 feet, and are hundreds of feet long. Many of the complexities of the Kingsport can be directly related to the development of an unconformity at the top of the overlying Mascot Dolomite. Erosion associated with the unconformity produced a widespread karst topography with an attendant paleoaquifer system. Ground water, apparently reacting to differences in solubility between limestone of the Kingsport and dense dolomite of the Mascot, is thought to be a major contributing factor in regional dolomitization and localization of solution-thinning and collapse features at the contact of the Kingsport and Mascot. Later mineralizing solutions invaded the paleoaquifer, locally depositing commercial quantities of zinc ore.

Virginia, Tennessee↗