Malignant melanoma of the urethra: a rare histologic subdivision of vulvar cancer with a poor prognosis

Malignant melanoma of the urethra is a rare tumour that is difficult to diagnose and treat, resulting in a poor prognosis. In this paper, we present the case of a 65-year-old woman who was referred to a gynaecologist because of a urethral mass that mimicked a caruncle. The tumour was removed by local excision, and a pathological analysis revealed a malignant melanoma. Distal urethrectomy was performed after three months with no evidence of residual tumour. There was no evidence of disease at a six-year followup. In this paper, we compare the epidemiology, treatment, staging, and prognosis of vulvar cancer in general to malignant melanoma of the vulva in particular

Report of the Workshop on Geologic Applications of Remote Sensing to the Study of Sedimentary Basins

The Workshop on Geologic Applications of Remote Sensing to the Study of Sedimentary Basins, held January 10 to 11, 1985 in Lakewood, Colorado, involved 43 geologists from industry, government, and academia. Disciplines represented ranged from vertebrate paleontology to geophysical modeling of continents. Deliberations focused on geologic problems related to the formation, stratigraphy, structure, and evolution of foreland basins in general, and to the Wind River/Bighorn Basin area of Wyoming in particular. Geological problems in the Wind River/Bighorn basin area that should be studied using state-of-the-art remote sensing methods were identified. These include: (1) establishing the stratigraphic sequence and mapping, correlating, and analyzing lithofacies of basin-filling strata in order to refine the chronology of basin sedimentation, and (2) mapping volcanic units, fracture patterns in basement rocks, and Tertiary-Holocene landforms in searches for surface manifestations of concealed structures in order to refine models of basin tectonics. Conventional geologic, topographic, geophysical, and borehole data should be utilized in these studies. Remote sensing methods developed in the Wind River/Bighorn Basin area should be applied in other basins

Paleoenvironmental Analysis and Test of Stratigraphic Cyclicity in the Nolichucky Shale and Maynardville Limestone (Upper Cambrian) in Central East Tennessee

The Upper Cambrian Nolichucky Shale and Maynardville Limestone (upper Conasauga Group) crop out along a succession of southeastward dipping imbricate thrust sheets, which trend northeast-southwest in the Valley and Ridge of eastern Tennessee. In the vicinity of Oak Ridge and Knoxville, Nolichucky and Maynardville outcrop and drill core have been examined at six localities. The Nolichucky contains an abundance of thick shale and thinly bedded shale and limestone, whereas the Maynardville is composed of very thick-bedded carbonate, predominantly limestone. In central east Tennessee fourteen major lithofacies are identified in the upper Conasauga Group. The Nolichucky/Maynardville sequence is subdivided into three parts representing: (1) a slightly deeper intracratonic basin (30-50 m water depth; lower Nolichucky, (2) a shallow intracratonic basin (5-30 m deep; upper Nolichucky), and (3) a peritidal platform (0-5 m deep; Maynardville). The Nolichucky Shale was deposited in a storm-dominated paleo­environmental setting, whereas the Maynardville Limestone is similar to other ancient tidally-influenced deposits. In the Nolichucky, the majority of carbonate production occurred in and around shoals and within cyanobacterial mats. Storms were effective in moving carbonate sediment off the shoals and mats into adjacent shale-dominated subtidal areas. The Maynardville represents small tidal flats that accreted vertically and migrated laterally. Sediment was produced in open-water subtidal areas, which were adjacent to tidal flats, and tides, storms, and fairweather waves transported sediment to nearby low-relief intertidal banks and supratidal islands. The distribution of facies along the Nolichucky/Maynardville bathymetric profile was much more irregular (mosaic-like) than predicted by the depositional model of earlier workers. An integrated approach of overlying substitutability analysis, embedded Markov chain analysis, and modified autoassociation analysis to verify statistically the occurrence of cycles in stratigraphic sequences is applied to the upper Conasauga Group of central east Tennessee. Stratigraphic sections within the Nolichucky Shale and in the Maynardville Limestone show weakly developed cyclicity, which is probably a result of the storm- and tide-dominated paleoenvironmental setting. Local processes were more important in controlling lithologic repetition than were larger-scale processes (e.g., geoidal, tectonic, or glacioeustatic). Large-scale processes have been documented in modern and other ancient settings, but their record may be masked in many sequences by local events

PROVENANCE OF THE NEOPROTEROZOIC OCOEE SUPERGROUP, EASTERN GREAT SMOKY MOUNTAINS

The Ocoee Supergroup is a sequence of Neoproterozoic, immature, continental rift facies clastic sediments. Potential source rocks were tested by analyzing modes of detrital framework minerals, detrital mineral chemistry, whole rock geochemistry and detrital zircon U/Pb geochronology by LA-ICP-MS for Ocoee siltstone-sandstone dominated formations. Ocoee units are arkosic to subarkosic siltstones/sandstones, and ternary tectonic discrimination diagrams confirm a continental basement uplift source. Alkali feldspar predominates over plagioclase feldspar. Detrital feldspar compositions of Ocoee sediments as a group are similar to feldspar in local basement granitic rocks except for high-Ca plagioclase grains present locally in basement granitic rocks. The high alkali content of the detrital feldspars in the Ocoee Supergroup is consistent with derivation from an A-type granite source terrane. Normative Q-A-P values, calculated from wholerock chemistry, and trace element diagrams are also supportive of an A-type granite source for these rocks. The siltstones and sandstones of the Snowbird Group contain high abundances of heavy minerals (zircon, titanite, ilmenite, epidote and apatite), which are dispersed among other detrital grains and as concentrations of heavy minerals in discrete laminae. ZTR index and titanite mineral chemistry suggest a granitic source for these sediments. Detrital zircon geochronology in Ocoee sediments indicates a dominantly Grenville (1000 to 1300 Ma) source for these sediments. The youngest zircon age in the basal Ocoee Wading Branch Formation (639±8 Ma) is related to rift magmatism and provides a minimum depositional age for the Ocoee Supergroup

Geochemistry and Mineralogy of Clastic Sediments of Tukau Formation: Implications on Provenance and Tectonic Setting

A study is proposed on the clastic sedimentary rocks of the Tukau Formation in the North-West Borneo using combined methods (i.e. geochemistry and petrography) to infer the provenance, tectonic setting and paleoweathering. Generally, Tukau sandstones are classified into quartz arenites , sublitharenites, litharenites, wacke and shale. Source rock is derived from the sedimentary to meta-sedimentary rocks dominated source with minor contribution from granitoids and ultramafic rocks. Tectonically, the Tukau Formation sedimentary rocks were deposited in a passive margin with minor extent towards active margin boundary

Paleomurenemine Arhaikumi-Proterosoikumi üleminekul Imandra-Varzuga rohekilda vööndis Loode-Venemaal

Väitekirja elektrooniline versioon ei sisalda publikatsiooneMaa ajaloos tähtsal Arhaikumi – Proterosoikumi piiril, ligikaudu 2,4 miljardit aastat tagasi ilmumus Maa atmosfääri vaba hapnik. Hapnikulise atmosfääri tekkimine tõi kaasa muutused Maa geokeemilistes aineringetes ja käivitas laiaulatusliku kontinentaalsete kivimite oksüdatiivse murenemise. Senini on oldud seisukohtal, et selline keskkond põhjustas laiaulatusliku sulfiidsete mineraalide lahustumise ja selle tulemusena intensiivse happelise murenemisimpulsi, mis omakorda tekitas toitainete plahvatusliku sissekande ookeanidesse, soodustades primaarproduktsiooni ning fotosünteetilise hapniku juurde tekkimist. Käesoleva doktoritöö eesmärgiks oli hinnata keskkonnatingimusi ja atmosfääri CO2 kontsentratsioone Kuksha murenemiskooriku tekkimise ajal 2,5 - 2,45 miljardit aastat tagasi ning analüüsida Imandra-Varzuga rohekivimite vööndi geoloogilise läbilõike Seidorechka, Polisarka ja Umba kihistute savikiltasid, et hinnata kontinentaalse murenemise intensiivsust enne ja pärast hapnikulise atmosfääri kujunemist. Doktoritöö tulemused näitavad, et Kuksha murenemiskoorik on moodustunud keskmisest intensiivsemal murenemisel nõrgalt happelistes tingimustes, kus aasta keskmine temperatuur oli ~12–13 °C ja keskmine sademete hulk 700–1100 mm/a, mis ligikaudu vastab tänapäevasele Vahemere piirkonna kliimale. Murenemiskooriku tekkimise ajal oli hinnanguline paleoatmosfääri CO2 osarõhk ainult 1–10 PAL. Samas ei ilmnenud selget murenemisintensiivsuse erinevust enne vaba hapniku ilmumist tekkinud Seidorechka kihistu setendite ja sellel järgnenud eeldatavalt hapnikulistes tingimustes tekkinud Umba kihistu setendite vahel. Seega võib väita, et hapnikulise atmosfääri tekkimisega kaasnev happelise murenemise impulss ei omanud märkimisväärset mõju üldisele silikaatide murenemise intensiivsusele. Meie andmed viitavad, et murenemisintensiivsus Arhaikumi ja Proterosoikumi üleminekul pigem langeb koos atmosfääri CO2 suhtelise sisaldusega, millega tõenäoliselt kaasnes ka üldine kliima jahenemine.The Archaean to Proterozoic transition is recognized by significant environmental disturbances triggered by the shift from anoxic to oxic surface environments during the Great Oxygenation Event (GOE) at ca. 2.4 Ga. The onset of oxidative weathering is thought to have caused an extensive acid attack in weathering due to oxidation of sulphide minerals in surface rocks. Chemical weathering itself has an important impact on the evolution of the Earth's surface environments by regulating atmospheric CO2 through a negative feedback mechanism and release of bio-limiting nutrients into the ocean. Therefore, palaeosols and fine-grained terrigenous sediments derived through weathering are important sources of information on environmental-climatic conditions of the past. The main aims of the theses are to characterize the weathering intensity, determine environmental conditions, estimate the atmospheric pCO2 using the Kuksha palaeoweathering crust (ca. 2.5–2.45 Ga), and to reconstruct the changes in silicate weathering intensity using the Imandra–Varzuga metasediments spanning across the Archaean–Proterozoic transition. The Kuksha weathering crust formed under acidic weathering conditions under cool temperate climate with mean annual temperatures ~12–13 °C and precipitation between 700 and 1100 mm yr–1 similar to modern Mediterranean climate. Despite the high weathering rates the estimated palaeoatmospheric pCO2 values range only within 1–10 PAL. However, there is no difference in overall silicate weathering intensity indicators between the Seidorechka Sedimentary and Umba Sedimentary formations deposited, respectively, prior to and after the GOE marking the onset of oxidative weathering. The results of this study suggest that the punctuated acidic weathering, caused by oxidation, did not affect the long-term weathering intensity. Instead, it seems that the overall silicate weathering decreased with the dropping atmospheric pCO2 levels during the Archaean–Proterozoic transition.https://www.ester.ee/record=b549647

8th Annual Jackson School of Geosciences Student Research Symposium, February 2, 2019

ConocoPhillipsGeological Science