Glen Rose Limestone Research Articles

ECOLOGICAL CHARACTERISTICS AND DISTRIBUTION OF ARBUTUS XALAPENSIS (TEXAS MADRONE) POPULATIONS IN CENTRAL TEXAS

Arbutus xalapensis Kunth (Texas madrone, Ericaceae) is found in western and central Texas, but its ecological characteristics are little known. Mature A. xalapensis plants were found in the Albert and Bessie Kronkosky State Natural Area in Kendall and Bandera counties, central Texas (29.740278 N, –98.838333 W). Habitats studied included Acer grandidentatum Nutt. (bigtooth maple) canyon bottoms, Juniperus ashei J.Buchholz/Quercus L. sp. (Ashe juniper/mixed oak) hillsides, and J. ashei uplands. Population characteristics were compared to habitat and surface geology. A total of 98 A. xalapensis plants were found in the communities studied. Differences were found for all parameters except height. Upland A. xalapensis trees had the lowest mean (±SD) density (2 ± 3 plants/ha), highest basal area (210 ± 190 cm2/plant), community elevation (573 ± 14 m) and height (4.09 ± 1.70 m/plant). Hillside communities had the highest density (61 ± 38 plants/ha), but lower basal area (110 ± 170 cm2/plant). The canyon bottom plant basal area was 80 ± 100 cm2/plant and density was 10 ± 5 plants/ha. The canyon bottoms had the deepest soil (27.2 ± 20.4 cm) and lowest elevation (510 ± 16 m). When geological substrates were examined, 128 additional plants were found. The largest plants were on the Fort Terrett member of the Edwards limestone (hard limestone, 230 ± 220 cm2/plant), but density was the lowest (2 ± 3 plants/ha). Whereas greater density was on the Upper Glen Rose limestone (softer limestone, 16 ± 7 plants/ha), where plants were smaller (110 ± 150 cm2/plant). Community type and geological substrate seem critical for growth of this species.

Sporadic gastrinoma - Diagnose and treatment - Case report

The Aptian–Albian Glen Rose Limestone (GRL) is an argillaceous shallow-marine carbonate deposit on the Central Texas Platform and contains the upper Trinity aquifer and the upper part of the middle Trinity aquifer. The GRL is divided into Upper and Lower GRL members, which have been further subdivided into hydrostratigraphic units (HSUs). This study uses an integrated ichnological and sedimentological approach to record changes in ichnofabric index (ii) as a proxy for bioturbation within the GRL and relates these changes to fluid flow. Fluid pathways within HSUs are controlled by the complex interaction of faults and fractures, karst development, and large-scale bioturbation-influenced porosity and permeability. The effect of bioturbation-influenced porosity as an aquifer characteristic is the least studied of these factors. Post-depositional solution enhancement of ichnofossils is also common and has increased lateral and vertical fluid connectivity in some HSUs. Most GRL strata are dominated by Thalassinoides networks, but also contain Palaeophycus, Planolites, Ophiomorpha, Serpulid worm tubes, rhizoliths, and Cruziana. Thalassinoides are commonly filled with coarser sediment than the surrounding matrix and act as fluid conduits within an otherwise low permeability matrix. Beds with ii3–4 and burrows with permeable fill transmit water readily. Beds with ii5–6 are commonly muddy and heavily homogenized, restricting fluid flow. Grainstone beds commonly have ii1–2 and are well cemented, restricting fluid flow to low intergranular flow. Pore systems dominated by Thalassinoides ichnofabrics, such as the GRL, are difficult to characterize on a large scale using many laboratory methods because they create heterogeneous flow paths depending on difference in permeability between the matrix and burrow fill. Understanding the effects of bioturbation-influenced porosity and permeability on subsurface fluid pathways is vital for creating a geologic and hydrostratigraphic framework for the Trinity aquifer.

Effects of Thalassinoides ichnofabrics on the petrophysical properties of the Lower Cretaceous Lower Glen Rose Limestone, Middle Trinity Aquifer, Northern Bexar County, Texas

The combined Edwards and Trinity aquifer system is the primary source of freshwater for the rapidly growing San Antonio and Austin metropolitan areas. The karstic Lower Cretaceous (Aptian–Albian) Lower Glen Rose Limestone (GRL) contains the middle Trinity aquifer and has been subdivided into six hydrostratigraphic units (HSUs) with distinct hydrologic characteristics. These HSUs were first identified in the subsurface via core examination at the Camp Stanley Storage Activity (CSSA) in northern Bexar County, Texas and were then correlated to associated gamma-ray and resistivity logs. The Trinity aquifer system is a telogenetic karst and fluid flow is directed primarily through solution-enhanced faults, fractures, and pervasive Thalassinoides networks because matrix porosity of both transmissive and confining HSUs is very low. Meteoric water infiltrates the Trinity aquifer through vertically-oriented faults and likely moves laterally through biogenic pores. Two 7.62cm diameter GRL cores and well logs from monitoring wells CS-MW9-CC and CS-MW5-LGR recovered from the CSSA were used to characterize the effect such large-scale Thalassinoides networks have on the petrophysical properties (resistivity and natural gamma-ray) of four HSUs (Honey Creek, Rust, Doeppenschmidt, and Twin Sisters HSUs). Resistivity logs show that resistance values >300Ω-m correlate with well-developed biogenic porosity and values of 650Ω-m are associated with solution enhancement of the Thalassinoides networks. These high resistivity zones are cyclical and are identified in muddy confining units, even when no changes in lithology or karstic development are identified. Pervasive Thalassinoides networks act as starting points for wide spread dissolution and lead to advanced karst development in transmissive HSUs. Natural gamma-ray logs do not reflect hydrologic characteristics directly, but are inversely correlated to resistivity logs and display m-scale cyclicity. Resistivity logs suggest that Thalassinoides networks are interconnected throughout strata within the GRL and when coupled with natural gamma-logs, the lateral distribution of these networks within HSUs can be correlated. Identifying such fluid pathways is of particular importance for wells not located in proximity to major faults and karstic features.

Bioturbation-influenced fluid pathways within a carbonate platform system: The Lower Cretaceous (Aptian–Albian) Glen Rose Limestone

The Aptian–Albian Glen Rose Limestone (GRL) is an argillaceous shallow-marine carbonate deposit on the Central Texas Platform and contains the upper Trinity aquifer and the upper part of the middle Trinity aquifer. The GRL is divided into Upper and Lower GRL members, which have been further subdivided into hydrostratigraphic units (HSUs). This study uses an integrated ichnological and sedimentological approach to record changes in ichnofabric index (ii) as a proxy for bioturbation within the GRL and relates these changes to fluid flow. Fluid pathways within HSUs are controlled by the complex interaction of faults and fractures, karst development, and large-scale bioturbation-influenced porosity and permeability. The effect of bioturbation-influenced porosity as an aquifer characteristic is the least studied of these factors. Post-depositional solution enhancement of ichnofossils is also common and has increased lateral and vertical fluid connectivity in some HSUs. Most GRL strata are dominated by Thalassinoides networks, but also contain Palaeophycus, Planolites, Ophiomorpha, Serpulid worm tubes, rhizoliths, and Cruziana. Thalassinoides are commonly filled with coarser sediment than the surrounding matrix and act as fluid conduits within an otherwise low permeability matrix. Beds with ii3–4 and burrows with permeable fill transmit water readily. Beds with ii5–6 are commonly muddy and heavily homogenized, restricting fluid flow. Grainstone beds commonly have ii1–2 and are well cemented, restricting fluid flow to low intergranular flow. Pore systems dominated by Thalassinoides ichnofabrics, such as the GRL, are difficult to characterize on a large scale using many laboratory methods because they create heterogeneous flow paths depending on difference in permeability between the matrix and burrow fill. Understanding the effects of bioturbation-influenced porosity and permeability on subsurface fluid pathways is vital for creating a geologic and hydrostratigraphic framework for the Trinity aquifer.

Bedrock, soils, and hillslope hydrology in the Central Texas Hill Country, USA: implications on environmental management in a carbonate-rock terrain

The Hill Country of Central Texas, USA, is undergoing rapid socioeconomic development, but environmental management of this region is hampered by misconceptions about local bedrock, soils, terrain, and hydrologic processes. The Hill Country is underlain mostly by Glen Rose Limestone (Lower Cretaceous) and exhibits a stepped terrain, which has been incorrectly attributed to alternating hard and soft bedrock strata. Other characteristics mistakenly attributed to this landscape include thin soils with scant water-retention capabilities, and rapid runoff as the dominant hydrologic process. This report presents new findings: unweathered bedrock is well indurated, but interbeds exhibit variable weathering rates. Recessive slopes (“risers”) on this stepped terrain result from rapid deterioration of strata having generally heterogeneous depositional fabrics (bioturbation and irregular clay partings) in contrast to ledge-forming strata having homogeneous fabrics. A stony regolith is thus formed beneath risers, providing porous and permeable ground that retards runoff and promotes the formation of moderately deep to deep (two-tiered) regolith/soil zones. These surficial materials on local steep slopes compose important natural environmental buffers; they support diverse biota and enhanced geochemical cycling of nutrients; they also exhibit significant water retention and enhanced erosion abatement. Proper land management demands recognition of these attributes in the siting, design, and construction of facilities.

Lower Cretaceous Orbitolinas from Venezuela

Lower Cretaceous Orbitolinas from Venezuela

Outcrop-to-Basin Stratigraphy and Structure of Glen Rose Limestone of Central Texas: ABSTRACT

The Glen Rose Limestone is a proven oil and gas producer in south Texas along the Stuart City reef trend. However, it has not been productive, except in minor occurrences, in the East Texas basin, even though it is present in an area of approximately 75,000 mi2 (195,00 km2) and attains a maximum thickness of 3,500 ft (1,067 m). This absence of production is believed to result from a lack of exploration rather than a lack of potential. Therefore, a regional study of the outcrop-to-basin stratigraphy and structure of the Glen Rose in central Texas was undertaken to correlate existing stratigraphic nomenclature and to determine the depositional and diagenetic history. Be relating these to known production, it should be possible to identify potential exp oration fairways. Cross sections were used in establishing stratigraphic correlations, resulting in a division of the Trinity Group different from that commonly seen in literature. The group is divided into the Glen Rose and Travis Peak subgroups, with the division at the outcrop placed at the Hensel-lower Glen Rose contact. However, in the basin, the Pearsall-Rodessa contact is used as it is time-equivalent to the division adopted at the outcrop. Examination of cores, cuttings, and sample logs defined the depositional and diagenetic environments of Glen Rose strata. Isopach maps and seismic sections were used to map distribution of facies tracts related to production. Facies and structure of known production areas were compared to those of untested areas to define possible exploration fairways and to map recommended exploration trends. Principal of these is the Stuart City reef trend. End_of_Article - Last_Page 548------------

Fossil decapod crustaceans from the Lower Cretaceous, Glen Rose Limestone of central Texas

Fossil decapod crustaceans from the Lower Cretaceous, Glen Rose Limestone of central Texas

ENVIRONMENT RECONSTRUCTION FOR A PART OF THE GLEN ROSE LIMESTONE, CENTRAL TEXAS

SUMMARYAn approximately 50 ft. stratigraphic section of the Lower Cretaceous Glen Rose Limestone was sampled at 24 separate localities in central Texas from the standpoint of reconstructing the depositional environment. Among these samples 199 representative specimens were selected and subjected to point‐count analyses, X‐ray analyses, and insoluble residue determinations. Statistical analysis of the accumulated data with an IBM 7090 computer yielded the following facies: Corbula facies—characterized by a relative abundance of thick‐shelled ostracods, thin‐walled miliolid foraminifers, and the small pelecypod Corbula martinae; steinkern facies—characterized by large mollusc steinkerns, cellular mollusc shells and the foraminifer Orbitolina; mudstone facies—typified by less than 10% sand‐sized grains; and mixed particle facies—characterized by worn skeletal and nonskeletal carbonate grains. The mud‐stone facies subsequently was divided into two subfacies: (1) lime mudstones—characterized by delicate skeletal constituents and lime mud, and (2) marly mud‐stones—consisting of a mixture of lime mud and terrigenous clay‐sized material. Similarly the mixed particle facies was divided into four subfacies: skeletal calcarenites—characterized by sand‐sized skeletal debris; skeletal wackestones—consisting of sand‐sized skeletal particles floating in a mud matrix; nonskeletal calcarenites—characterized by nonskeletal carbonate grains; and nonskeletal wackestones—consisting of nonskeletal carbonate grains floating in a mud matrix. In addition limey sandstone, dolomite, and stromatolite facies were distinguished on the basis of relatively obvious textures and compositions.The attributes of these facies as evidenced by the 199 statistically analyzed specimens were then used to assign each of the additional samples (350) to a particular facies and to identify the distribution of these facies in the field. A reconstruction of the depositional environment was made for each facies, and the following depositional history was interpreted from the resulting facies pattern.The lowermost beds of the unit, consisting largely of stromatolites and nonskeletal calcarenites, are interpreted as representing deposition in very shallow, probably intertidal, waters, Following the deposition of these beds, the depth of water increased

Basement Rocks of Pico Etereo Area, Northern Coahuila, Mexico: GEOLOGICAL NOTES

Fragments of muscovite-chlorite-graphite schist in a volcanic pipe agglomerate of the Pico Etereo area resemble schist exposed along the faulted western flank of Sierra del Carmen near Boquillas, Coahuila. The agglomerate consists mostly of rounded- to sub-rounded fragments of limestone and rhyolite or trachyte in a rhyolitic matrix. Minor amounts of baked shale, orthoquartzite, and schist are scattered throughout the matrix. Many of the limestone fragments were derived from the Glen Rose Limestone. The schist fragments were derived from the interior zone of the Ouachita structural belt which underlies much of the northern part of the Coahuila platform. Depth to the basement is at least 2800 ft in the Pico Etereo area.

Central Texas Lower Cretaceous Stratigraphy: ABSTRACT

The Trinity Group is divided into a lower unit consisting of the terrigenous Hosston Formation overlain by the carbonate Sligo; a middle unit called the Pearsall, made up of the Hammett shale, Cow Creek limestone: and Bexar shale; and an upper unit which includes the Hensel sand, overlain by the Glen Rose limestone. Limestone, dolomite, and marl of the section between the base of the Upper Trinity and the top of the Edwards were deposited in shallow water behind the Stuart City coral-rudistid barrier reef. Lower Glen Rose reefs and the Stuart City reef formed the southwestern, southern, and eastern barriers of the Ferry Lake anhydrite evaporation pan. The Fredericksburg Group includes the strata between the base of the Bee Cave limestone and the base of the Kiamichi. The Washita Group includes the Kiamichi, middle (Kiamichi) Edwards, upper Edwards, Georgetown, Del Rio, and Buda formations. The upper, or the lower Edwards should be renamed. Structural elements which affected Lower Cretaceous deposition include the spasmodically positive Belton high (new term), the Round Rock syncline (new term), two synclinal troughs behind the Stuart City reef, and the Sample fault system (new term). Up-to-the-coast faults are dominant southeast of the axes of the synclinal troughs, and down-to-the-coast faults are dominant northwest. End_of_Article - Last_Page 1967------------

Nummoloculina in Lower Cretaceous of Texas and Louisiana

Several occurrences of the miliolid Nummoloculina in the Lower Cretaceous of Texas (lower Glen Rose through upper Devils River limestones) and one occurrence in the Lower Cretaceous of northern Louisiana (lower Glen Rose limestone) are reported for the first time. The geologic range of Nummoloculina as ascertained by the writers is Lower Cretaceous to Recent. Nummoloculina limestones in Texas are here reported from the upper Devils River limestone (Georgetown limestone equivalent) in Val Verde County and the Edwards limestone in La Salle and Maverick counties. Nummoloculina occurring in the Devils River limestone in Val Verde County is figured and discussed. Nummoloculina from the El Abra miliolid member of the El Abra formation of northern Mexico (Lower Albian through Lower Cenomanian) is figured for comparison. The uppermost Devils River limestone and the upper El Abra miliolid member are compared, but no correlation is implied. Following Norton's zonation of foraminifers, miliolid limestone environments would correspond most closely with his Zone A where the water is 0-5 fathoms deep and the temperature is 21°-32°C. Miliolids occurring in abundance are facies foraminifers characteristic of back-reef and inter-reef environments; therefore, they are useful in paleoecology. Although miliolid limestones in Texas vary in age within, but are restricted to the Lower Cretaceous (Sligo through upper Devils River limestones), they may be of local or regional value in the differentiation of large stratigraphic units within the Sligo through upper Devils River limestones. Miliolid limestones are used successfully in parts of southwest and central Texas to mark the faunal top of the Edwards limestone. However, in the Devils River area, or in any other area where reefs were formed in Washita as well as Fredericksburg limestones, such differentiation based on miliolids is unsatisfactory.

Development of limestone reservoirs in Comal County, Texas

The Edwards limestone, and to a lesser extent the Comanche Peak limestone and the lower part of the Glen Rose limestone below, all of Lower Cretaceous age, form one of the most extensive ground‐water reservoirs in Texas. As a result of normal faulting, these formations are connected by underground channels to form a hydrologic unit which is partly artesian and partly unconfined. Observations in Comal County show that the development of the reservoir by solution is closely related to the geologic history, in which complex faulting and the disconformity between the Edwards and Georgetown limestones are important factors. Various phases of development are shown in different fault blocks, depending upon length of exposure at the surface. The Edwards limestone, which contains the main channels of underground drainage, is almost uniformly permeable from top to bottom, whereas the older, but more recently exposed lower part of the Glen Rose limestone is generally relatively impermeable except where exposed by mature streams.

Trinity Sediments of North and Central Texas

ABSTRACT The Trinity group, except in Red River area, is divided into three stratigraphic units which in ascending order are Travis Peak or Basement Sands, Glen Rose limestone, and Paluxy sands. The coarse-grained clastics, larger than [1]/[16] min., are characterized by texture, degree of abrasional wear, and heavy mineral assemblages. The fine-grained materials, the silt and clay sizes, constitute about 50 per cent of some of the deposits. The limestones were analyzed for carbonates and insoluble residues.

Geology of the Santiago Peak quadrangle, Texas

The U. S. Geological Survey topographic sheet of the Santiago Peak quadrangle, Texas, covering 275 square miles, includes the southwestern part of the Marathon uplift, trans-Pecos Texas, where post-Cretaceous folds of the Santiago Mountains cross Paleozoic structural trends. Paleozoic sediments deposited in the Llanoria geosyncline aggregate 15,000 feet and were deformed in Pennsylvanian time by orogenic movements directed from the southeast. The Cretaceous sea, which advanced over beveled Paleozoic strata, deposited 2500 feet of sediments, mostly limestones. The Glen Rose limestone is the oldest Cretaceous formation. The Maxon sandstone may be Fredericksburg in age. The Devils River limestone is divided into four members, two of which can be correlated, at least in part, with the Edwards and the Georgetown formations of central Texas. The Aguja is the youngest Cretaceous formation. Post-Cretaceous doming of the Marathon uplift did not extend west of the Santiago Mountains, in which the chief structural feature is a monocline of Cretaceous strata with the limb overturned to the west. In places the lower flexure of the monocline is broken by a thrust fault, with thrusting from the east. The folding and faulting are believed to have been related to orogeny in the Sierra Madre Oriental 100 miles to the southwest. Large normal faults, trending north-south and northwest-southeast, produced blocks now tilted westward. Post-Cretaceous sills of alkalic syenite occur west of Santiago Mountains.

Dinosaur Tracks in Hamilton County, Texas

Previous articleNext article FreeDinosaur Tracks in Hamilton County, TexasW. E. WratherW. E. Wrather Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Journal of Geology Volume 30, Number 5Jul. - Aug., 1922 Article DOIhttps://doi.org/10.1086/622908 Views: 125Total views on this site PDF download Crossref reports no articles citing this article.

Dinosaur tracks in the Glen Rose limestone near Glen Rose, Texas

Dinosaur tracks in the Glen Rose limestone near Glen Rose, Texas