Browsing by Subject "Geology, Stratigraphic"
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Item Biostratigraphy of Jonah quadrangle, Williamson County, Texas(1950-06) Marks, Edward, 1926-; Young, Keith, 1918-2004This paper presents a zonation of the Austin chalk and the Burditt marl, divisions of the Austin group in the Jonah quadrangle, Williamson County, Texas. The Austin chalk consists of the Inoceramus subquadratus Schlüter faunizone, Gryphaea wratheri Stephenson faunizone, Inoceramus undulatoplicatus Roemer faunizone, Hemiaster texanus Roemer faunizone, Exogyra laeviuscula Roemer faunizone, and the Exogyra tigrina Stephenson epibole. The Burditt marl contains the Ostrea centerensis Stephenson faunizone. The Austin-Taylor contact has been traced from the southeastern to the northeastern corner of the area. The relations of the Taylor marl and some of the Terrace gravels are discussed. The outcrop, lithology, and paleontology of the Eagle Ford shale, which underlies the Austin group, are also included.Item The Black Shale Basin of West Texas(1939-08) Cole, Charles Taylor, 1913-; Bybee, Halbert Pleasant, 1888-1957The Black Shale Basin of West Texas covers an area in excess of 21,000 square miles and includes the region from Terrell and Pecos Counties eastward to Menard and Kimble Counties. It extends from Real, Edwards, and Val Verde northward beyond Glasscock and Upton Counties. This basin includes such local basins as the "Midland Basin," and "Val Verde Basin," of Frank E. Lewis, the "Sheffield Channel," and the "Kerr Basin." Reasons are given for the belief that the black shale sediments in this basin were derived from rocks south of this area. The shale ranges in age from Bend (lower Pennsylvanian) through Clear Fork (middle Permian). The shale of the Midland Basin has been divided into three distinct zones. Pre-Cretaceous erosion has removed the offlapping Permian shale in the extreme southern portion of the area leaving Pennsylvanian directly beneath the Trinity. The problem of stratigraphy is complicated by gradation and lack of diagnostic fossils. There is a great divergence of opinion as to correlative formational units derived from a study of the well cuttings.Item Geology of the Cowboy Pass area, Confusion Range, Millard County, Utah(1957-06) Haenggi, Walter Tiffany, 1933-; Rush, Richard W.Paleozoic, Mesozoic and Cenozoic rocks totaling about 15,000 feet in thickness are exposed in the Cowboy Pass area in the Confusion Range. The Paleozoic sedimentary rocks are carbonates, with small amounts of sandstone and shale, and the Mesozoic sedimentary rocks are shallow water limestone and shale. Cenozoic deposits are alluvium, lacustrine beds and small amounts of volcanic material. The trend of major folds and faults changes sharply from northerly to northeasterly at Cowboy Pass, and this change is accompanied by minor faulting and folding. Major structures are the result of post Lower Triassic-pre Cenozoic orogeny. During Cenozoic time, high angle normal faults developed, accompanied by local volcanic activity.Item Pre-Mesozoic geology of Huizachal-Peregrina Anticlinorium, Ciudad Victoria, Tamaulipas, and adjacent parts of eastern Mexico(1992-08) Ramírez-Ramírez, Calixto, 1949-; Salvador, AmosThe Huizachal-Peregrina Anticlinorium is a large NNW-trending structure in the front ranges of the Sierra Madre Oriental of Mexico (23° 45ʹ N; 99° 10ʹ W). The breached core of the anticlinorium exposes three major geologic terranes: (1) . A late Precambrian granulite terrane (Novillo Gneiss) remarkably similar in composition, appearance, grade and age of metamorphism to rocks of the Grenville Province, especially the Adirondacks; (2). A mid-Paleozoic low-grade metamorphic complex (Granjeno Schist) of volcano-sedimentary origin with ophiolite rock assemblages, that resemble rocks of the Ouachita-Appalachian inner zones; and (3). A strongly folded and faulted section of Paleozoic fossilifireous sedimentary strata, more than 1500 m thick, similar to the rocks of the Ouachita frontal zone exposed in the Marathon region of Texas. Except for an extensive subcrop terrain of Permo-Triassic granitic intrusives, the terranes in the area studied represent "unique samples" of the Pre-Mesozoic basement framework of eastern Mexico. These terranes belong to two ancient superposed orogenic systems: the Late Precambrian Oaxacan (Grenville) and the Paleozoic Huastecan (Ouachita-Appalachian) structural belts. Based on the geologic study of these pre-Mesozoic terranes at Huizachal-Peregrina, and compared with the widely spaced and limited outcrops (and sub-crops) of equivalent rock units of eastern Mexico, a tectonic model is proposed which interprets the granulite terrane as representative of continental crust, and the low-grade metamorphic terrane as rocks that accumulated on top of the ocean crust of a marginal basin. This latter sequence experienced a complex history of deformation and metamorphism as it was subducted towards the east, culminating 330 m.y. ago. The onset of Carboniferous-Permian orogenic flysch sedimentation is interpreted to have occurred when the marginal basin became closed by an arc-continent collision. The Permo-Triassic granitic rock terrane of the subsurface of the Gulf Coastal Plain represents the magmatic roots of that volcanic arc. The pervasive NW to NNW-trending structural grain, of the Oaxacan and Huastecan structural belts south of Huizachal-Peregrina through Oaxaca, when compared to the NE-trending distribution of Precambrian and Paleozoic terranes in the United States are compatible with the existence of a proposed zone of large left-lateral displacement across northern Mexico.Item Recent and ancient volcaniclastic sedimentation on an active continental margin(Texas Tech University, 1979-12) Vessell, Richard KentNot availableItem Sequence stratigraphy and depositional history of the upper Cañon del Tule, Las Imagenes, and Lower Cerro Grande Formations, central Parras Basin, northeastern Mexico(2003) Bermúdez Santana, Juan Clemente; Buffler, Richard T.This dissertation describes the results of a field-oriented sequence stratigraphic study of a 900-m-thick Maastrichtian interval in the middle portion of the Upper Cretaceous Difunta Group. Basic analysis of rock features and their stratigraphic arrangement were used to subdivide the interval into transgressive (TST), highstand (HST), and falling stage (FSST) systems tracts and to recognize their bounding surfaces. The progradational offshore to lower shoreface highstand (HST) deposits of the upper Cañón del Tule Formation and the underlying transgressive (TST) deposits, contain gastropods and bivalves common in shallow marine Lower Maastrichtian strata. However, the occurrence of the ammonite Coahuilites sheltoni restricts these rocks to the lower Upper Maastrichtian. In the Late Maastrichtian, the final stage of shallow marine sedimentation of the upper Cañón del Tule Formation was characterized by an abrupt change. Accommodation space was reduced in proximal settings, and the shoreline and coarse-grained facies belts migrated basinward in response to a relative sea level fall (forced regression). Wave scouring of the seafloor, and rip and longshore currents produced a regionally extended forced regression surface and sequence boundary characterized by meter-scale gutter casts. The FSST upper shoreface to foreshore deposits of the uppermost Cañón del Tule Formation include a ridge-forming sandstone of variable thickness. Its internal stratigraphic architecture suggests that high-frequency pulses of sea level risings punctuated the forced regression. During this process, thick, aggradational red deposits of the lower Las Imágenes Formation (FSST) accumulated over the adjacent coastal plain until an intermittent marine transgression began. The initial transgressive pulses occurred across a rapidly subsiding coastal plain, which favored the development of charophytes in fresh and brackish water environments, associated with benthonic foraminifers, ostracods, oysters, Ophiomorpha and Thalassinoides. Mixed-load probably meandering rivers drained the coastal plain bounded by lagoons and extensive shoreface and offshore environments for this part of the Late Maastrichtian Gulf Coast of México. After this stage of intermittent marine transgression, shallow seas and transgressive (TST) deposits of the lower Cerro Grande Formation covered the region.Item Sequence stratigraphy and tectonics of the Guantao and Minghuazhen Formations, Zhao Dong field, Bohai Bay, eastern China(2007-05) Castellanos, Hugo Alberto, 1974-; Fisher, William L.; Mann, Paul, 1956-Item Sequence stratigraphy of the upper San Andres Formation and Cherry Creek Tonque (Permian, Guadalupian), southern Brokeoff Mountains, New Mexico(1992-08) Fitchen, William M.; Buffler, Richard T.Outcrop exposures of the upper San Andres Formation and Cherry Canyon Tongue (Permian, Guadalupian) in the Brokeoff Mountains, New Mexico provide a seismic-scale cross-section through the margin of the Northwest Shelf and adjacent Delaware Basin. Stratal patterns such as onlap, offlap, downlap, and toplap, which are commonly used by seismic interpreters to identify sequences and systems tracts in the subsurface, can be observed directly in the area and integrated with facies distributions to generate a high-resolution sequence stratigraphic framework. The upper San Andres Formation and Cherry Canyon Tongue comprise a third-or fourth-order sequence (85 to 145 m-thick) bounded by unconformities and their correlative conformities (sequence boundaries). Lowstand/shelf margin, transgressive, and highstand systems tracts within the sequence were recognized on the basis of bounding surfaces and cycle stacking patterns. Cycle stacking patterns were analyzed with respect to geometry, component facies distribution, thickness, and the nature of lateral termination (e.g. onlap). The basal sequence boundary of the upper San Andres-Cherry Canyon Tongue sequence overlies the middle San Andres highstand platform. A basinward shift in facies tracts across this sequence boundary is evidenced by the vertical progression from offlapping ramp margin and slope strata of the middle San Andres highstand systems tract to onlapping, ramp crest strata of the upper San Andres lowstand/shelf margin systems tract. Erosion of underlying slope and toe-of-slope strata is evident along the boundary; carbonate megabreccias locally overlie the sequence boundary at the toe-of-slope. As a result of the strongly offlapping and toplapping character of the upper San Andres sequence, the upper sequence boundary intersects early highstand systems tract strata in the platform interior and late highstand systems tract strata closer to the terminal ramp margin. The sequence boundary is marked locally by a karst horizon; the best development of karst occurs in ramp margin strata of the early highstand systems tract. The karst is characterized by sandstone-filled rundkarren, grikes, and caverns that extend up to 30 m downward into San Andres strata. Toplap and minor stratal truncation mark the sequence boundary along the top of the late highstand systems tract. Subtidal to peritidal cycles of the Grayburg Formation (lowstand/shelf margin systems tract and transgressive systems tract) onlap the upper sequence boundary. The lowstand/shelf margin systems tract of the upper San Andres sequence is composed of a thin (6 to 25 m-thick) aggradational to slightly progradational cycle set that onlaps the basal sequence boundary along the platform and downlaps the sequence boundary for a distance of 100 m along the slope. Peritidal sandstone and carbonate facies of the systems tract pass basinward within a few hundred meters into a distinctive bryozoan-sponge-crinoid shelf margin buildup, which in turn passes basinward into toe-of-slope allodapic carbonates and discontinuous carbonate megabreccias derived from the underlying sequence. Relatively thin ramp crest cycles of the lowstand/shelf margin systems tract are capped by a transgressive surface that is locally erosional. The stacking pattern of cycles in the lowstand/shelf margin systems tract reflects relatively low rates of accommodation and sediment production. Siliciclastic sediment bypass across the shelf and slope may have been active during deposition of this systems tract. The transgressive systems tract of the upper San Andres sequence comprises 1) an aggradational to weakly progradational cycle set of ramp crest/ramp margin carbonates and siliciclastics (40-45 m-thick), 2) a proximal, onlapping slope apron complex of carbonates and siliciclastics (25-30 m-thick), and 3) a distal, marine onlap-wedge of basinal siliciclastics (the lower Cherry Canyon Tongue, 30-80 m-thick). Ramp margin/upper slope carbonates of the transgressive systems tract downlap the transgressive surface along the platform. On the platform, the transgressive systems tract is composed of relatively thick ramp crest cycles containing a high ratio of subtidal vs. supratidal facies. The systems tract is capped by three to four sandstone-based cycles, the upper two of which can be traced downslope into the slope apron complex. The top of the slope apron complex is downlapped by strongly progradational cycles of the overlying highstand systems tract. The downlap or maximum-flooding surface marks the top of the transgressive systems tract. Towards the basin, allodapic carbonates of the slope apron complex thin and pinch out into the body of the lower Cherry Canyon Tongue. These relationships indicate that lower Cherry Canyon Tongue sandstones were bypassed to the basin during high-frequency lowstand intervals superimposed on a longer term relative sea level rise. In contrast, allodapic carbonates within the slope apron were supplied to the slope during high-frequency highstand intervals. The highstand systems tract of the upper San Andres sequence (15-85 m-thick) comprises strongly progradational cycle sets composed of ramp crest through slope carbonates and sandstones. Clinoform cycles downlap onto the slope and basinal segments of the transgressive systems tract (lower Cherry Cherry Canyon Tongue). The highstand can be subdivided into two major cycle sets, termed the "early highstand" and "late highstand" respectively. The early highstand is characterized by carbonate-dominated sigmoid progradational clinoform cycles that can be traced from the ramp crest to the toe-of-slope. In the platform interior, early highstand cycles are thin and contain a higher ratio of supratidal facies relative to cycles of the transgressive systems tract. Early highstand cycles aggraded the ramp crest some 15-20 m and prograded 1-2 km into the basin. The late highstand is characterized by mixed carbonate-siliciclastic, sigmoid to oblique progradational clinoform cycles that toplap shelfward into the upper sequence boundary at low (1-2°) to high (10-15°) angles. Late highstand cycles did not aggrade the platform, rather, the former ramp crest area was a subaerial sediment bypass zone during deposition of these cycles. Late highstand cycles prograded 5-6 km into the basin. A progressive decrease in accomodation rates through the highstand systems tract is inferred from a decrease in the ratio of aggradation to progradation, a concommitant change from sigmoid to oblique progradational style, an increase in clinoform slope angle, and an increase in siliciclastic sediment flux. The basal sequence boundary of the upper San Andres sequence can be correlated to the unconformity between the Cherry Canyon Tongue/Brushy Canyon Formation and Cutoff Formation along the Western Escarpment (southern Guadalupe Mountains). The Brushy Canyon Formation, which is restricted to the basin, is interpreted as a "lowstand fan" equivalent in time to the basal sequence boundary and perhaps to part of the lowstand/shelf margin systems tract in the Brokeoff Mountains. The basal sequence boundary correlates to the top of the lower-middle San Andres sequence on the Algerita Escarpment (central Guadalupe Mountains). This sequence boundary can also be correlated to the base of the Cherry Canyon Tongue in Last Chance Canyon (central Guadalupe Mountains), although correlation between the platform sections of the Brokeoff Mountains and Last Chance Canyon is somewhat uncertain. The upper sequence boundary correlates to the San Andres-Grayburg contact on the Algerita Escarpment and in Last Chance Canyon. The correlation of this boundary to the Western Escarpment remains uncertain. The progressive decrease in accommodation exhibited by upper San Andres late highstand strata in the Brokeoff Mountains, and the inferred correlation of lower Grayburg shelf sandstones into the upper third of the basinal Cherry Canyon Tongue, supports the hypothesis that the terminal ramp margin of the upper San Andres sequence lies 8-10 km north of the Western Escarpment near the New Mexico-Texas state line. This entails that the upper sequence boundary lies within the Cherry Canyon Tongue on the Western Escarpment.Item Stratigraphic analysis of reflectivity data, application to gas reservoirs in the Burgos Basin, Mexico(2003) Barrios Rivera, Jorge; Fisher, William L.; Hardage, Bob A.Item Stratigraphy, structural geology, and tectonics of a young forearc-continent collision, western Central Range, Irian Jaya (western New Guinea), Indonesia(1996-05) Quarles van Ufford, Andrew I. (Andrew Ian), 1967-; Cloos, MarkNew Guinea has long been recognized by geologists as the location of geologically recent mountain building. This study combined field mapping, stratigraphic and remote sensing analysis along and near the Gunung Bijih (Ertsberg) mine road and mining district in order to analyze the geologic development of the collisional New Guinea orogen. As a result of the youthfulness and the quality of data, it is possible to constrain distinct parts of orogenic evolution to 1 or 2 m.y. The southern Central Range of New Guinea is located on the northern Australian continental margin. The southern one-third of the Central Range, exposed along the Gunung Bijih mine access road, is a 30-km-wide, north-dipping homocline exposing an apparently 18-km-thick Precambrian or Early Paleozoic to Cenozoic sequence. Following rifting in the early Mesozoic and until the Middle Miocene, the northern Australian continent was a passive margin. The Central Range of Irian Jaya formed when the Australian passive margin was subducted beneath and collided with a north-dipping subduction zone in the Middle Miocene. Litho- and biostratigraphic analysis of the New Guinea Limestone Group in the Gunung Bijih mining district and regional stratigraphic correlation indicates that the first evidence of subaerial exposure and erosion of the orogen is the widespread deposition of siliciclastic, synorogenic strata at ~12 Ma. I name this event the Central Range Orogeny. There is no evidence of an Oligocene orogenic event in the Irian Jaya region as has been described to the east in Papuan New Guinea. Deformation in the Central Range is dominated by ~12 to ~4 Ma southwest verging (210°-220°) contraction and minor east-west wrenching. This deformation is equally accommodated, there is no evidence for strain partitioning in the Central Range. Lithospheric-scale cross sections, incorporating field observations, predict the Central Range Orogeny is divided into a pre-collision and collisional stage. The pre-collision stage is the bulldozing of passive margin sediments in a north dipping subduction zone. The collision stage occurs when buoyant Australian lithosphere can not be subducted. The collision stage results in basement involved deformation and lithospheric delamination of the already subducted Australian plate.Item Structural evolution of the Warwick Hills, Marathon Basin, West Texas(1987-12) Coley, Katharine Lancaster, 1956-; Muehlberger, William R.A detailed structural analysis was conducted of the Warwick Hills at the northeast tip of the doubly-plunging Dagger Flat anticlinorium, Marathon Basin, west Texas. Field work delineated a folded duplex structure composed of three horses. Thrust transport was towards the northwest and resulted in a hinterland-dipping duplex. Initial thrusting In the Warwick Hills shortened the area by 2.2:1 (54%). Post-thrusting, the duplex underwent nearly isoclinal folding creating two anticlines and a syncline, second-order folds to the Dagger Flat anticlinoium. Folding combined with thrusting brought the total shortening of the rock package to 6.5:1 (85%). Earlier estimates gave a shortening for the Warwick Hills of 3:1. Finally, the folded duplex was extended by oblique tear faulting that offset the folded thrusts accommodating extension of the major folds in a northeast direction. These tear faults occurred post-plunging of the folds and were the last deformational movements that affected the Warwick Hills. The Ordovician Maravillas and Devonian Caballos Formations acted in the Warwick Hills as a structurally competent couplet. Addition or subtraction of this couplet, or units in this couplet, controlled the location of the major and minor thrusts, the style and shape of folds, and the location of the fold hinges. Bounding the couplet are incompetent shales of the Ordovician Woods Hollow and the Mississippian Tesnus Formations. Thrusts in the Warwick Hills duplex have a basal décollement in the Woods Hollow shale and ramp up through the Maravillas/Caballos couplet with an upper décollement in the Tesnus shale. The entire duplex was primarily folded by flexural slip (i.e. concentric folds) as evidenced by slickensides oriented parallel to bedding and perpendicular to fold axes, the constant thickness of the competent layers and the change in fold shape with depth. Fold wavelength, as determined from the couplet in the lowest thrust sheet, averages ~1,300 m and the average fold axis for the Warwick Hills, as determined stereographically, plunges ~54° N90°E. Shale in the Woods Hollow and Tesnus Formations bounding the couplet, flowed passively during folding into the cavities that were created by the bending of the more competent units. Lower and upper boundaries of disharmonic folding developed in the Woods Hollow and Tesnus Formations respectively. Unique to this area when compared to the rest of the anticlinorium are the presence of tightly folded thrusts and steep east-trending fold axes. The anticlinorium plunges in the Warwick Hills because it drapes off a down-to-the-northeast basement fault. Folds were "dragged" or diverted to the east during thrusting of the duplex over this transversely-oriented paleotopographic fault scarp, or were diverted subsequent to thrusting of the duplex by strike-slip movements at depth along the basement fault.Item Three-dimensional stratal development of a carbonate-siliciclastic sedimentary regime, Northern Carnarvon Basin, Northwest Australia(2002) Cathro, Donna Louise; Fisher, W. L.; Austin, James AlbertDetailed stratigraphic interpretation of continental margin clinoforms is a necessary first step in understanding the link between this complex stratal architecture and large-scale processes resulting in progradation. Maps derived from a 3D seismic volume (40-55 Hz) nested within a regional 2D multichannel seismic grid (25-35 Hz), and tied to nine hydrocarbon exploration wells, show the detailed morphological evolution of five prograding clinoformal sequences in the Northern Carnarvon Basin (NCB), northwest Australia. Depocenters concentrated along northeast-southwest oriented, linear clinoform fronts are governed by latitudinal variations in sediment productivity. Fronts change from smooth to highly dissected, with intense gullying apparent after the mid Miocene optimum. Bottomsets remain relatively sediment-starved without the development of aprons on the lower slope and basin. Small-scale variability suggests heterogeneous sediment dispersal through these slope conduits. Along-strike sediment transport superimposed on northwest-oriented progradation changes from south-directed in the late Oligocene to north-directed in the late mid-Miocene suggesting a reorganization of circulation in the southeastern Indian Ocean. Prominent seismic discontinuity surfaces represent intervals of shallow paleo-water depth and flooding of the shelf. Exposure surfaces are subordinate. Rather than build to sea-level, progradation occurs with shelf paleo-water depths of 20-200 m. Therefore, onlap onto the clinoform front is not coastal and the sensitivity of the clinoforms to sea-level changes is muted. However, in the midMiocene, partial exposure of the shelf and development of karst topography indicate paleo-water depth falls of 60-180 m across two sub-sequence boundaries. The sequence stratigraphic framework is combined with a twodimensional, forward kinematic and flexural model for deformation of the lithosphere to determine the distribution, magnitude and history of CretaceousTertiary compression-induced inversion across the Dampier Sub-basin in the NCB. Inversion simultaneously creates and destroys accommodation space at different wavelengths superimposed on long wavelength subsidence and eustatic variations that impact the entire margin. Inversion anticlines focused along earlier rift fault systems are small, temporally and spatially variable relative to the total accommodation space created in the sub-basins during rifting and thermal subsidence. Santonian inversion represents ~4 km shortening, whereas the four modeled events in the Miocene each represent ~200-400 m of shortening across the modeled section.