Digitized Theses and Dissertations (1940 - 2009)
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Item A 2D phase-shift migration algorithm for laterally varying velocity fields and an analysis of ophiolite-derived models of accretion(1986) Ashabranner, Donald E.; Casey, John F.; Gardner, Gerald H. F.; Hall, Stuart A.; McDonald, John A.A two dimensional depth migration algorithm capable of successfully handling laterally varying velocity fields has been developed. This technique was achieved by dividing a data set into overlapping subsets of equal width (number of traces) with adjacent subsets being offset by one trace. Each subset is migrated by a phase-shift algorithm using the velocity function of its central trace so that lateral velocity variations can be incorporated by introducing different velocity functions for successive subsets. Two different approaches have been developed, one operating in the frequencywavenumber (F - K) domain while the other operates in the frequency-space (F - x) domain, and both correctly migrated synthetic data in the presence of lateral velocity variations. Computation time, window width, and wrap around problems were addressed and based on these investigations, the F - x scheme was found to be superior, but neither algorithm is suitable for a mini-computer. The F - x scheme was to be applied to real seismic data collected over a fast spreading mid-ocean ridge in an effort to assess an ophiolite-derived model of accretion. Because of the C.P.U time required in the application of this algorithm to small data sets, this was deemed unfeasible. In lieu of this, a diffraction-stack migration was applied but no conclusions could be drawn because of the pre-stack processing history of the data.Item A geologic study of artesian thermal mineral water with emphasis on the Texas Gulf coastal plain(1950) Kister, Tom L.; Fan, Paul H.This thesis is a preliminary study of artesian thermal mineral water. Emphasis is placed on the Texas Gulf Coastal Plain and Houston Hot Wells, Harris County, Texas. An endeavor is made to determine origin of water, source of heat, method of mineralization, economic possibilities, and applications of the study. Brief discussion and analysis of the many factors is presented. Artesian thermal mineral water represented nearly all the natural occurring unpotable water in the Texas Gulf Coastal Plain. Large amounts of oil, gas and potable water are produced in the region. The water studied is invariably associated with these commercial fluids. Houston Hot Wells is located roughly in the center of the Texas Gulf Coastal Plain, The water has been the nucleus of one of the few health and pleasure resorts of this type in Texas. The water from the single well is representative of much artesian thermal mineral water. The temperature of the water is compared favorably with well known health resorts. A discussion of origin stresses connate and meteoric waters. A broader interpretation of the definition for connate water is suggested to include much water in the Texas Gulf Coastal Plain. Emphasis is placed on the natural increase in temperature of the earth with depth. It is postulated to be the source of heat for most of the water in the region. The evidence for this conclusion is given in some detail, and many causes of variances are listed. An attempt is made to set forth the factors involved in mineralization and to evaluate them as far as possible. An effort is made to show that waters of high mineral content are not necessarily of connate origin. A brief comment on Texas Gulf Coastal Plain stratigraphy and structure and their effect on artesian thermal mineral water is given. A determination of stratigraphy and structure at Houston Hot Wells is presented. The economic aspect of this water is treated in a separate chapter. The possible applications both theoretical and practical furnish a chapter, and are stressed throughout the thesis.Item A geologic study of the Jergins oil field(1950) Kazim, S. A.; Fan, Paul H.Jergins Oil Field occupies the upthrown part of a z-shaped subsurface structure. The production comes from sands at the top of Frio, from an area of about 318 acres. The peculiar thing about the subsurface structure of this field is it's downthrow to the northwest which is unusual in areas near the Gulf Coast.Item A geologic study of the Krotz Springs oil field, Louisiana(1950) Courtney, Cecil; Fan, Paul H.The Krotz Springs Oil Field, Louisiana, is located ab out forty miles directly west of Baton Rouge, Louisiana, in the Atchafalaya River Basin. This basin is part of the Gulf Coast Geosyncline. The age of the sediments encountered at Krotz Springs varies from Eocene to Recent. The deposition of these sediments was controlled by the axis of sinking of the Gulf Coast Geosyncline, and the axis of downwarping of the Mississippi Structural Trough. [...]Item A geologic study of the Livingston field(1949) Miron, SamThe Livingston field is located in the southern part of Polk County, Texas. Over the greater part of the field, the outcropping formation is the Willis, while in the extreme southern portion some Lissie is found in outcrop. The author has made use of electrical well log surveys, fault plane contours, cross-sections, and horizon contour maps in working out the structure of the field. Formations encountered in the wells are all Tertiary, from the outcropping Willis to some forty three hundred feet of Wilcox in the deepest well. The circular outline and amount of structural relief suggests that the field is a deep-seated dome, which is dissected by a complex network of faults. Outstanding among the structural features is a system of major faults dividing the structure into three upthrown blocks and an arched down-thrown block segmented by minor faults. The formations steepen and thicken on the downthrown sides in the vicinity of the faults, and the throws of most faults diminish upwards. These factors are Indicative of continuous activity of the faults since their origin, and the existence of an active upward thrust during their geologic existence. Four separate oil horizons are present in the field. The two most prolific are in the topmost sands of the Yegua and Wilcox. The third is a thin ten foot sand of Sparta age, absent in the western part of the field, and the fourth is a correspondingly thin sand of Hockleyensis age, of limited extent.Item A lithofacies study of the Frio formation in the upper Gulf Coast region of Texas(1958) Branham, Thomas B.; Bishop, Margaret S.A regional lithofacies study of the subsurface Frio formation in the upper Gulf Coast of Texas was undertaken to determine as much as possible the environmental conditions that may have existed during Frio time. Various lithofacies maps were prepared in order to delineate the various areas of deposition with respect to the lithofacies patterns produced. Such regional surveys, interpreted in the light of modern depositional environments and the sedimentary processes operating therein, can be very helpful in acquiring an understanding of the sediments deposited during past geologic ages.Item A Markovian computer simulation of conservative groundwater tracer behavior during transport(1985) Kemner, Mark Louis; Woronow, Alexander; Butler, John C.; Lawrence, James R.; Hostetler, Charles J.; Batten, George W., Jr.The simulation of solute behavior during transport in the subsurface is a valuable tool in water and waste management. However, accurate simulation is not always possible or feasible using today's methods. The three main methods used to solve groundwater contaminant transport are computer models, laboratory column experiments and field monitoring. Most computer models are of the finite elements or finite difference type. These models are workable and useful, but the Markov model presented here is generally more flexible and can use less computer time and have lower storage requirements. Laboratory experiments are difficult to match accurately with field conditions as many of the processes taking place are dependent on scale and thus distort results in small laboratory experiments. Field monitoring takes lengthy periods of data gathering, and without adequate characterization of subsurface conditions, causal relationships are often difficult to infer. The computer model of the behavior of a conservative groundwater contaminant presented here is a direct simulation of the effects of advection, mechanical dispersion, and molecular diffusion. The model is based on the Markov principle of dependent random variables, in a computer code that does not use finite elements or finite difference techniques. A form of the diffusion equation is used for contaminant diffusion and dispersion. When tested against a carefully constructed laboratory column by Sudicky (1983) the results closely match and therefore should provide an accurate simulation of the conservative processes taking place in actual groundwater systems, given the parameters for each field situation. This model should provide a satisfactory base for further developments in conservative and reactive processes taking place in groundwater systems, complementing field and laboratory work. Such processes could include adsorption, ion exchange, radioactive decay, and chemical reactions.Item A microstructural investigation of the deformational conditions and kinematics of flow in peridotite tectonites from the North Arm Mountain massif, Bay of Islands ophiolite complex, Newfoundland(1987) Brink, Ronald Steven; Casey, John; Elthon, Donald; Gardner, Gerald H. F.Microstructural and petrofabric investigations of cumulate and residual peridotite rocks from the North Arm Mt. massif, Bay of Islands ophiolite, Newfoundland suggest that the two units share a similar deformational history. Comparable stresses (350-425 bars from olivine neoblast and subgrain paleo- piezometry), strain rates (about 1 x 10 -14 sec), deformational temperatures (950[degrees]C+ from slip systems inferred through olivine petrofabric and kink band studies), mineral shape anisotropies, olivine petrofabrics and metamorphic textures (porphyroclastic-equigranular) are found in rocks from both sides of the cumulate-residual boundary. A low-temperature, high-strain, high-stress, high-strain rate deformation with NW (subduction direction) peridotite flow (from olivine Z-axis and spinel Iineation trends) characterizes the lowermost three km of North Arm massif rock. Stresses, strains and strain rates decline in magnitude up section while some flow directions above the three km level are found to trend NE (the sea floor spreading direction inferred from sheeted dike orientations). Basal North Arm massif rocks are considered to have undergone a subduction-related deformation that overprints original mantle upwelling- derived microstructures. Deformation is heterogenous in upper North Armmassif peridotites, with subduction-related strain partitioned into discrete shear zones.Item A microstructural study of mantle peridotites from the Mid- Atlantic Ridge, near 23[degrees](1988) Xia, Chunshou; Casey, John F.; Norman, Carl E.; Butler, John C.; Geanangel, Russell A.A suite of serpentinized peridotites was recovered at 23[degrees]N, on the western wall of the Mid-Atlantic Ridge rift valley, near the Kane Fracture zone (MARK area). Most of the rocks have undergone serpentinization in the range of 35 to 94%, averaging 74%. The majority of the rocks are harzburgite in composition. Detailed textural studies of the primary phases indicate that there are two major textural types, protogranular and porphyroclastic, preserved in the rocks. Slip system determinations from olivine petrofabrics and kink bands indicate that high temperature (010)[100] slip system was dominant during the processes of deformation of these rocks. Stress and strain studies indicate that these rocks were once deformed under a low to moderate stress and high strain conditions of the subaxial mantle. After the stages of high temperature ductile deformation, the rocks underwent progressive retrograde and lower temperature hydration. Brittle deformation occurred during and after serpentinization of these rocks. The intense hydration of the mantle rocks suggests that large amounts of seawater have been involved in the alteration processes, and that seawater has circulated down to appreciable depth below the "Moho" boundary. [...]Item A multivariate statistical determination of some recent morphospecies of the genus Elphidium from Gulf of Mexico(1968) Fisher, Fred E.; Sadlick, Walter; Maddocks, Rosalie Frances; Osburn, Hobart G.An analysis involving a set of 15 variables on each of 212 specimens of the genus Elphidium sub-equally distributed among 7 samples from the north-western Gulf of Mexico results in 6 groups which are both observationally and statistically distinct. These 6 groups correspond to 9 previously described species. The raw data are subjected to the following series of multivariate statistical techniques: 1. Statistical normalization (Z-form) and data condensation (factor analysis) 2. Formation of protogroups and a residual pool of ungrouped specimens (geometric distance) 3. Addition of ungrouped specimens to protogroups and verification of groupings (discriminant analysis) 4. Combination of protogroups (canonical variates or graphical technique) 5. Procedures 3 and 4 are repeated until no more specimens can be added to the protogroups and no more protogroups can be combined. The resulting sets of specimens are the final statistical morphospecies. The original 9 species are reduced to 5 species: Elphidium discoidale, E. galvestonense, E. gunteri, E. incertum and E. poeyanum. Elphidium matagordanum is provisionally considered a junior synonym of E. incertum mexicanum; Cribroelphidium poeyanum, Elphidium delicatulum and E. translucens are provisionally considered junior synonyms of E. poeyanum. Geographic distributions of the groups in this study indicate that there may be three faunal areas of Elphidium in the Gulf of Mexico: the northern Gulf characterized by E. gunteri, the western Gulf characterized by E. discoidale and E. galvestonense, and the southern Gulf characterized by E. incerturn mexicanum.Item A new Monte Carlo model of the development of the lunar megaregolith(1987) Cashore, Jac; Woronow, Alex; King, Elbert A., Jr.; Butler, John C.; Mote, Victor L.A new Monte Carlo model is utilized to examine the development of the lunar megaregolith by impact cratering processes. The computer code incorporates some of the techniques and insights of previous cratering models; however, it also attacks many of the unresolved problems in those earlier models, particularly that of "edge effects". Additionally, this model includes more recent morphological information on crater geometries and ejecta blanket geometry, as well as an updated crater production function. The crater and ejecta blanket morphologies now contribute to the evolving topography such that each new impact encounters a more topographically realistic terrain. Ejecta blankets are now allowed to extend to three crater diameters beyond the final relaxed crater bowl, sufficient to allow the formation of continuous ejecta blankets for all modeled crater sizes. Estimates have been developed for the average megaregolith thickness formed by impact processes. This improved model predicts greater values for the minimum megaregolith thicknesses than those of previous models. This thickness increase results mainly from three factors; 1) the use of the observed Iimar highlands crater size-frequency curve as the highlands production function, 2) the retention of topographic information as cratering proceeds, and 3) different models for the crater bowl and ejecta blanket geometries. Comparison of the model results with the 20 to 25 km seismic horizon on the moon, possibly attributable to the base of the megaregolith, suggests a cumulative bombardment of two to five times the number of craters presently preserved on the lunar highlands surface. The relationship of megaregolith thickness to the elevation of the final evolved topography has been studied, with the result that the megaregolith is thicker in areas of elevation extremes, both high and low. The thickness is smallest in areas of less disturbed topography.Item A petrographic and chemical study of ternary feldspars(1977) Zabel, Garrett E.; Carman, Max F.; Butler, John C.Luna Vista sill Is a recently exposed, irregular, elongate Intrusive body consisting of a trachytic, sparsely porphyritic sodium-rich quartz alkali microsyenite. The sill is broadly basin shaped and is slightly discordant with underlying sediments of Late Cretaceous age. Alkali feldspar phenocrysts and felsic groundmass account for about 84 percent of the rock. The sill was originally more laterally extensive, especially toward the northeast and northwest where sapping caused by the underlying claystone has brought about extensive retreat of the cliffed margin. Feldspar phenocrysts and groundmass crystals from the sill were analyzed with the electron microprobe and were determined to have a narrow compositional range of zoning which follows trends indicated by phase equilibrium studies of feldspar systems. Two synthetic gel mixtures that were similar in composition to the sill rock feldspar composition and a finely powdered portion of the sill rock were melted and crystallized experimentally at linear cooling rates at 5, 2, and 1 kb. Feldspar crystals grown in these experiments were also zoned according to predicted trends. There are five different zoning patterns found in the crystallized gel samples which are mainly controlled by the rate at which crystallization components arrive at the growing surface. The phenocrysts of the natural rock are believed to have crystallized at much slower cooling rates and stabilized at conditions closer to an equilibrium state than did the crystals formed in the experimental runs, where considerable departure from equilibrium conditions prevailed. This prevented extensive comparison of crystals from the two sets of conditions.Item A petrographic and geochemical study of Wildhorse Mountain, Brewster County, Texas(1978) Indest, Stanley J.; Carman, Max F., Jr.; Butler, John C.; Wentworth, Wayne E.Wildhorse Mountain is located just north of Big Bend National Park in the Terlingua Uplift area. The mountain was mapped and samples were studied to determine the shape of the intrusion and to elucidate the crysatllization history of the magma. The Wildhorse Mountain microsyenite hypabyssal intrusion has two distinct parts, the southwest portion is a plug and the northeast portion is a sill-like extension from the plug. Other intrusions in the mapped area, which range from alkali microsyenites to leucomicromonzo- diorites, and the Wildhorse intrusion are emplaced in the Upper Cretaceous Pen and Aguja Formations. The microsyenite contains multiphase feldspar together with ferroaugite and biotite phenocrysts in a groundmass of alkali feldspar, quartz, biotite and magnetite. Chemical analyses, modal analyses and its position on variation diagrams suggest the magma was a highly differentiated component of an alkaline rich suite of rocks. Detailed crystallographic studies show that feldspar crystallized in three phases: first plagioclase, then anorthoclase, and finally sanidine growing epitaxially, each phase mantling the previously the previously crystallized one. The three phases are optically distinct and exhibit a different "tracht" for each. Tracht is also dependent on grain size as crystal growth relationships vary from larger phenocrysts to microphenocrysts and groundmass feldspars All feldspar phases are compositionally zoned, as seen optically and determined by electron microprobe analyses. The phase relations suggests rapid crystallization of biotite, plagioclase and possibly early anorthoclase in a magma chamber, followed by reaction of biotite and meta-stable formation for the rest of the anorthoclase and sanidine during transportation and final emplacement of the mass at shallow depth. This crystallization sequence exemplifies the relatively high temperature low pressure conditions found in most of the intrusions of the Big Bend region.Item A petrographic study of the Anacacho Limestone (Upper Cretaceous) of Texas(1958) Harvill, Lee L.; Fan, Paul H.; Greenwood, Robert; Bishop, Margaret S.The Upper Cretaceous Anacacho limestone is exposed in scattered outcrops from eastern Kinney County to western Bexar County. The formation unconformably overlies the Austin chalk and is overlain unconformably by the Escondido clays, occupying the stratigraphic position of the Taylor group. A total of thirty-six rock specimens were taken from seven localities along the outcrop of the Anacacho limestone. Thin sections were made from fourteen of the specimens, Insoluble residues were run on seven of the specimens, and X-ray diffraction patterns were made of three specimens. A detailed study of the fabric, mineralogy, and porosity was made of each specimen. In eastern Kinney County, the limestone members of the formation consist of an alternating succession of strata possessing the fabric of biohermal reef rock and detrital reef rock. The middle, "Milam chalk", member consists mainly of chemically precipitated calcite with some clay and detrital quarts^ suggesting a lagoonal environment. The actively growing portion of the reef probably migrated back and forth, producing an interfingering of biohermal reef rock, detrital reef rock, and chalk. Eastward from Kinney County to western Bexar County the Anacacho limestone possesses the fabric of detrital reef rock, and is overlapped from the east by the Taylor marl. The absence of biohermal reef rock from the eastern portion of the Anacacho limestone suggests that the actively growing portion of the reef existed north of the present outcrop and has been removed by erosion. The principal fossils in the Anacacho reef are pele- cypods and bryozoans. Of the porosity visible under the binocular microscope, that which is definitely secondary is many times as great as that which is possibly primary. It was impossible to demonstrate conclusively that any of the porosity is truly primary. In the abundantly asphaltic portions of the Anacacho, the contact between the asphaltic and nonasphaltic rock was seen to cut across the bedding both in hand specimens and in gross aspect in the asphalt mines. The cutting of the bedding planes by the asphalt contact suggests that the asphalt invaded the limestone and was not deposited contemporaneously with it. The fact that the asphalt does not entirely fill the pore space of the rock, but forms a coating on the limestone fragments suggests that the asphalt is the residuum of a lighter oil which lost its volatile constituents.Item A petrographic study of the Leon Mountain analcite syenogabbro in the Terlingua area, Brewster County, Texas(1963) Krowski, Stanley P.This paper deals with the process of differentiation in an analcite syenogabbro sill of Tertiary age in the Terlingua area of West Texas. Four collecting traverses across this sill revealed various differentiated phases, including a syenite ridge, thin pegmatoid zones in the upper part of the sill, and fine-grained felsic stringers throughout the sill. Universal stage and index of refraction measurements of the principal mineral constituents indicate an initially homogeneous magma, in which crystal fractionation created a large amount of late magmatic alkalic and aqueous liquid. Modal analyses of thin sections yield no definite evidence that crystal settling, as a method of separating liquid and solid took place. Textural studies, supported by theoretical considerations, suggest that part of the residual liquid migrated to the upper regions of the sill, aided perhaps by filter pressing, accounting for enrichment of the upper one-third of the sill in alkalic minerals. Portions of the liquid were concentrated in a narrow zone, where they partially resorbed earlier-formed minerals. The high water content of the initial magma lowered the viscosity of the residual liquid and facilitated its movement. The water also created a late-stage high vapor pressure, giving rise to felsic stringers. Excess water formed primary analcite, and was active in deuteric alteration.Item A petrotectonic study of the Tesnus formation in the Marathon Basin, West Texas(1954) Clardy, Arthur L., Jr.The Tesnus formation is the basal Pennsylvanian strata found in the Marathon Basin of West Texas. It is a non-marine geosynclinal formation which was deposited in the Llanorian geosyncline. THe purpose of this work was to make a petrographic and tectonic study of the members of the Tesnus formation in an attempt to understand the changes which took place in both the depositional environment and the source area during the Tesnus times. [...]Item A quantitative study of Late Eocene Nummulites (Foraminiferida), Jackson Stage, Southeastern United States(1969) Barnett, Richard S.; Sadlick, Walter; Butler, John C.; Rhodes, Benjamin T., Jr.Paleontological analysis of extensive new collections from surface exposures of the Jackson Stage in the eastern Gulf Coast Province has determined the presence of five nummulitid species: Nummulites willcoxi Heilprin, 1882; N. heilprini Hantken, 1886; Operculina floridenis (Heilprin), 1884; 0. mariannensis (Vaughan), 1928; and Heterostegina ocalana Cushman, 1921. N. willcoxi is redescrihed and N. heilprini reinstated. Three sample groups of N. willcoxi and one of N. heilprini were examined by factor and canonical variate analysis. The twenty nine quantitative test variables used in the analyses include external dimensions, embryonic dimensions, and dimensions and counts recorded in the first four volutions of each test. Principal component factor analysis yielded eight or nine common factors which account for over 80 per cent of observed test variability. Four well resolved factors explaining over 60 per cent of test variability are associated with the embryonic growth stage, mature growth stage, external size and form, and chamber volume in relation to size. The extra factors are not clearly identifiable, probably reflect observational error, and may be correlated with the first four. Canonical variate analysis very effectively distinguished ten essential test variables out of the original twenty nine, and gave three canonical variates which collectively account for all the observed test variability. Two canonical variates account for about 95 per cent of test variability. The first canonical variate diagnoses morphospecies. The second canonical variate distinguishes between populations of megalospheric N. willcoxi. Two form groups of N. willcoxi are recognized by their different patterns of increase in chamber volume. The thin lenticular form grew rapidly in chamber height in its outer two or three volutions. The more inflated, biconvex form accommodated relatively more of its increase in chamber volume in alar prolongations. The two form groups of N. willcoxi are from different stratigraphic levels, but from very similar carbonate shoal habitats, as indicated by the lithology of the enclosing limestones of the Ocala Group. Specimens from a transitional lithofacies differ in their smaller external dimension, and a lower, less variable growth rate following the thin lenticular pattern. Test variation in larger Foraminiferida is the product of interacting heriditary and environmental factors. This systematic quantitative examination of variation, correlation and interrelations in fossil Nummulites demonstrates that canonical variate analysis can show how populations of a single species differ from one another. When the effects of sedimentary variables on fossil test morphology can be quantified, it will be possible to objectively discriminate between adaptive and evolutionary trends in test variation.Item A seismic stratigraphic interpretation and geohistory analysis of the Sable Island area of the Scotian Shelf, Eastern Canada(1985) Davin, Christopher Gerard; Sheriff, Robert E.; McDonald, John A.; Nugent, Robert C.; Gardner, Gerald H. F.A stratigraphic interpretation and geohistory analysis of the Sable Island area of the Scotian Shelf, offshore eastern Canada, was done using twelve hundred kilometers of seismic data and a full suite of logs from six wells. Major structural features and seismic sequences were identified and tied throughout the seismic grid. In addition depositional systems were identified from well and seismic information using Vail's techniques of analyzing relative coastal onlap patterns. Several major conclusions were made from this study. A basement Hinge Zone, related to the initial rifting of Pangea, exerted a major influence on Jurassic deposition. It was especially effective in controlling the updip limit of the Argo salt. In places the salt occurs as diapirs that extend almost to the surface. According to time thickness trends within the surrounding rocks, these salt diapirs were emplaced in latest Cretaceous or Early Tertiary times. An extensional glide plane fault system, replete with associated toe structures of over pressured shales formed on the continental slope during Cretaceous and Tertiary times. The slump features and debris flows that overlie these listric faults appear to have been triggered by oversteepening of the Tertiary and Quaternary clinoforms at the shelf edge. Geohistory analysis for three separate locations indicates that crustal subsidence was controlled by a single episode of lithostatic cooling that began 160 M.Y.B.P., the onset of significant continental drift. This is in agreement with published conclusions of studies of other parts of the Atlantic continental margin. Prominent shifts in coastal onlap patterns in the Tertiary and Quaternary successions have been interpreted in terms of the Vail sea level charts. By eliminating thermal tectonic subsidence as the control mechanism of short term shifts in the depositional record, sea level charts can be used as an age prediction tool.Item A shallow geothermal survey of Durkee Oil Field and Woodgate Fault, Harris County, Texas(1980) Ambs, Loran Dean; Hall, Stuart A.; Van Siclen, Dewitt C.; O'Neill, Michael W.This study was conducted northwest of Houston, Texas in two areas of intensive investigation: Durkee Oil Field and a nearby segment of Woodgate Fault. Temperature measurements made with thermistors at a depth of 2 meters revealed temperature anomalies caused by sources at depth and in the near surface. At Durkee Oil Field, a cool anomaly of about 1[degrees]C was found to be caused by a reverse drag fold at a depth of about 6000 feet. Two warm anomalies of about 1[degrees]C were found to be the result of two distributary channel sands at 7000 feet depth. Another warm anomaly of about 1[degrees]C and perpendicular to the channel sands, was found to be the result of a fault intersecting the surface. Where Woodgate Fault possessed a scarp, a temperature maximum was found directly on the scarp. Where no scarp was visible, temperature measurements made at 2 meters depth were successfully used to trace the fault and some of its associated fractures. The shape of temperature anomalies on and near the fault were found to be related to the pattern of ground water flow in the area. The shape of a temperature anomaly measured across a growth fault in the Gulf Coast may be useful in predicting the direction the fault plane dips.Item A short study of the modification of stream sediments during transportation, Elk Creek, Black Hills, South Dakota(1968) Cameron, Kenneth L.; Blatt, Harvey; Zwicky, Laurie BowmanElk Creek originates on the Precambrian metamorphic rocks of the Central Black Hills. Between the last outcrop of Precambrian rock and the Hogback Eidge, the outer boundary of the Black Hills, the stream flows eastward across the regional strike, and through 15 miles of Paleosoic and Mesozoic carbonates, shales, and fine-grained quartz sandstones. Both the Precambrian and Paleozoic rocks within the Hills are cut by shallow, quartz-bearing intrusions of Tertiary age. From the Hogback Ridge to its junction with the Cheyenne River, a distance of 85 stream miles, the stream flows eastward across the Plains and through Cretaceous shales and Cenozoic terrace gravels. Rock fragronts dominate the sand»sized sediment released from the crystalline source rocks, which include fine-grained from schists, amphibolites, and shallow intrusives ("volcanics"). Only a small amount of quartz coarser than silt-size is being released by these rocks. Elk Creek can be divided into 3 segments on the basis of its competences (1) from the Central Black Hills to the Hogback Ridge (15 stream miles); (2) from the Hogback Ridge to the "knickpoint" (40 stream miles) 1 (3) from the "knickpoint" to the Cheyenne River (45 stream miles). The stream is eroding its valley and transporting sediment in stream segments (1) and (3); however, aggradation is the dominant process in segment (2). Because little sediment presently being eroded from the Black Hills is being transported to the Plains, the composition of the sand-sized non-shale strew sediment on the Plains,is controlled by the terrace gravels. The terrace gravels are similar in compositlffin, but not identical, to the Recent stream sediment west of the Hogback Ridge. At the time of the deposition of some of the terrace sediment the following conditions existed; (1) the headwaters of Elk Creek drainage basin extended farther to the north in the Black Hills than at present, and contained a larger proportion of "volcanic" source rocks; (2) the eastern portion of the drainage basin wvs receiving arkosic sediment from the southern Black Hills; and, (3) the competence of the stream was greater than at present. A detailed examination of sand»sised sediment along the length of the stream suggest the following; (1) most fine-grained schist and amphibolite frayaenta are mechanically destroyed with less than 15 miles of transport in high gradient streams in this climatic region; (2) volcanic rock fragsyants are relatively durable and only a small percentage is lost due to mechanical abrasion during the first 100 miles of stream transport; (3) rowading of volcanic rock fragments does not occur in sediment finer than very coarse sand during the first 100 miles of stream transport. Hornblende decreases from 95 percent to 3 percent of the very fine sand-size non-opaque heavy mineral suite during the first 100 miles of transport in Elk Creek. This loss is due to dilution, Little if eny hornblende is lost due to chemical weathering or abrasion. If in the distant future a petrographer examined a sand-sample from near the present mouth of Elk Creek, he proably could recognize all the major source rock types with the exception of the terrace gravel. He would not, however, correctly estimate their relative percentages, Few, if any, petrographers would suspect that most of the non-shale sediment was derived from a mountainous darnel uplift, with mo»o than 8000 feet of structural relief, lass than 100 miles upstream.