Cephalopod Diversity within a Concretionary Inverval of the Pierre Shale (Upper Cretaceous) in Dawes County, Northwestern Nebraska

A concretionary interval within the Pierre Shale, where it outcrops across northern Dawes County, is characterized by a diversity of cephalopod taxa. The interval falls within the ammonite zones of Exiteloceras jenneyi to Baculites cuneatus of the upper Campanian. Three or more of the following cephalopod taxa have been collected at each of the seventeen sites described herein: Eutrephoceras dekayi (Morton); Baculites compressus Say; B. cuneatus Cobban; Didymoceras cheyennense (Meek and Hayden); Exiteloceras jenneyi (Whitfield); Jeletzkyites nodosus (Owen); Placenticeras intercalare Meek; P. meeki Boehm; and Solenoceras cf. S. crassum (Whitfield). The interval that yields cephalopod diversity comprises a stratigraphic thickness of about 15 to 20 meters and appears to occur roughly 300 meters above the base of the Pierre Shale in northeastern Dawes County. The fossils are present within calcareous concretions imbedded in gray to olive-gray shale in the lower portion of the upper part of the Pierre Shale in this area. The interval seemingly correlates, at least in part, with the lower unnamed shale member of the Pierre Shale in the Red Bird area in eastern Wyoming

The Distribution of Precious Metals in High-Grade Banded Quartz Veins from Low-Sulfidation Epithermal Deposits: Constraints from µXRF Mapping

High-grade ore zones in low-sulfidation epithermal deposits are commonly associated with the occurrence of banded quartz veins. The ore minerals in these veins are heterogeneously distributed and are mostly confined to ginguro bands, which can be identified in hand specimen based on their distinct dark gray to black color. Micro-X-ray fluorescence element maps obtained on representative samples of banded quartz veins show that Au occurs together with Ag minerals in some of the ginguro bands, but Au can also be present in quartz bands that are light gray to white and cannot be macroscopically distinguished from barren bands. The occurrence of compositionally distinct ginguro and gankin bands, the latter being a new term coined here for colloform quartz bands containing primarily electrum or native gold, can be explained by temporal changes in the composition of the ore-forming thermal waters or variations in the conditions of ore deposition. Textural relationships, including the dendritic shape of ore minerals that appear to have grown in a matrix of silica microspheres, suggest that the ginguro and gankin bands have formed as a result of rapid deposition associated with vigorous boiling or flashing of the thermal waters

Characteristics of gastro-esophageal reflux episodes in Barrett's esophagus, erosive esophagitis and healthy volunteers

BACKGROUND: Gastro-esophageal reflux is considered a major culprit in the pathogenesis of Barrett's esophagus (BE). Still, there is controversy on the role of weakly acidic and weakly alkaline reflux in BE. To compare characteristics of reflux episodes patients with BE, erosive esophagitis (EE), and healthy volunteers (HV). METHODS: One hundred consecutive patients with BE (75 short-segment BE, 25 long-segment BE), 50 with EE and 48 HV underwent multichannel intraluminal impedance-pH off-therapy. We quantified esophageal acid exposure, characteristics, and proximal extension of reflux episodes. KEY RESULTS: Total and acid reflux episodes gradually increased from HV [28 (17.5-43) and 18 (8-31)] to EE [73.5 (54-96) and 52 (39-68)], short-segment BE (SSBE) [83 (73.2-131) and 65 (43.3-95)] and long-segment BE (LSBE) [105 (102-187) and 77 (75-107)]. Weakly acidic reflux episodes were significantly higher (P < 0.05) in LSBE [36 (27.5-50.5)] and SSBE [34 (18.5-41)] compared to EE [21.5 (15-37)] and HV [19 (14-25)]. No differences in terms of proportion of acid, weakly acidic and weakly alkaline reflux were found [HV (49%-49%-2%) vs EE (68%-32%-1%) vs SSBE (65%-34%-1%) vs LSBE (69%-30%-1%); P = ns]. In LSBE, a higher percentage of reflux episodes (P < 0.05) reached the proximal esophagus (59%) compared with SSBE (43%). CONCLUSIONS & INFERENCES:   Barrett esophagus patients have more severe reflux as shown by the number of acid and weakly acidic reflux episodes, re-reflux episodes and proximal migration. Given that PPI change only the pH of the refluxate, the role of weakly acidic reflux in Barrett's patients on acid suppressive therapy warrants further investigation