Co-seismic surface displacement of the June 21, 2022 M_(W)6 Khōst,Afghanistan earthquake from InSAR observations

A robust estimation of the earthquake location, seismic moment, and fault geometry is essential for objective seismic hazard assessment. Seismic events in a remote location, specifically in the absence of seismic and GNSS networks, can be investigated effectively using the In SAR-based technique. This study adopts the Differential Interferometric SAR(DIn SAR) technique to quantify the co-seismic surface displacement caused by the June 21, 2022, Khōst M_(W)6 earthquake that occurred along the western plate boundary between the Indian and Eurasian plate. The interferograms show that the maximum surface deformation occurred on the northwest and southwest of the fault line. From coherence, the Line of Sight(LOS) displacement, and the co-seismic surface displacement analysis, it has been observed that surface deformation was most pronounced in the southwest region of the fault line, and the surface has moved to the opposite direction along the fault line, which indicates a sinistral slightly oblique strike-slip movement. This In SAR-based observation appears consistent with the seismic waveforms derived from co-seismic surface displacements. Further, it has been argued that the slip deficit accumulated during the period of the last about 48 years along the frontal region of the northward extension of the Suleiman range and associated fault zone is qualitatively estimated at about 1.5 m, which is consistent with the seismic waveforms derived finite slip model.

Geochemical modeling to aid experimental design for multiple isotope tracer studies of coupled dissolution and precipitation reaction kinetics

It is a challenge to make thorough but efficient experimental designs for the coupled mineral dissolution and precipitation studies in a multi-mineral system, because it is difficult to speculate the best experimental duration, optimal sampling schedule, effects of different experimental conditions, and how to maximize the experimental outputs prior to the actual experiments. Geochemical modeling is an efficient and effective tool to assist the experimental design by virtually running all scenarios of interest for the studied system and predicting the experimental outcomes. Here we demonstrated an example of geochemical modeling assisted experimental design of coupled labradorite dissolution and calcite and clayey mineral precipitation using multiple isotope tracers. In this study, labradorite(plagioclase) was chosen as the reactant because it is both a major component and one of the most reactive minerals in basalt. Following our isotope doping studies of single minerals in the last ten years, initial solutions in the simulations were doped withmultiple isotopes(e.g., Ca and Si). Geochemical modeling results show that the use of isotope tracers gives us orders of magnitude more sensitivity than the conventional method based on concentrations and allows us to decouple dissolution and precipitation reactions at near-equilibrium condition. The simulations suggest that the precise unidirectional dissolution rates can inform us which rate laws plagioclase dissolution has followed. Calcite precipitation occurred at near-equilibrium and the multiple isotope tracer experiments would provide near-equilibrium precipitation rates, which was a challenge for the conventional concentration-based experiments. In addition, whether the precipitation of clayey phases is the rate-limiting step in some multi-mineral systems will be revealed. Overall, the modeling results of multimineral reaction kinetics will improve the understanding of the coupled dissolution–precipitation in the multi-mineral systems and the quality of geochemical modeling prediction of CO_(2) removal and storage efficacy in the basalt systems.

Competition between Coral and Algae in Tertiary and Quaternary Reefs: Greenhouse to Icehouse Transitions

The competition between coral and algae in marine reefs is pervasive through geologic time;that competition determines the structure and composition of reef communities, which we see in the fossil record. However, the relationships between coral and calcareous algae in reefs are poorly understood. To study this relationship, several hand samples and thin sections were examined from nine different foralgal reef localities around the world. Foralgal reefs typically extend from about 20 m depth or shallower on the seaward side of the reef. The first section is Salt Mountain, Alabama, which preserves a Paleocene reef. It contains a high percentage of red coralline algae with benthic foraminifera. The second section is IDOP-U1376, IIA Limestone, it is Middle Eocene, in the form of an isolated reef sandwiched between two igneous beds. The third section is the Utoe’ Limestone, New Caledonia, it is Middle Eocene in age and is composed mainly of grain-boundstone units with some igneous interlayered. The fourth section is the Darnah Formation in the West-Darnah roadcut section, Northeast Libya, it is Middle Eocene in age, it is composed of highly fossiliferous limestone (corals, red coralline algae, echinoids, mollusks, foraminifers, and bryozoans). The fifth section, the Al Bayda Formation (Algal Limestone Member) in Northeast Libya, is in the Drayanah—Al Abyar roadcut, Northeast Libya, it has several species of algae but also includes a high percentage of buildups of coral species. The sixth section is the Oligo-Miocene Al Faidiyah Formation (Al Fatayah Cement Quarry) limestone unit in Northeast Libya. The seventh section is (Core-core 20) late-early to middle Miocene Limestone Unit-Cicuco Field, NW Colombia. The eighth section is the Benghazi Formation at Benghazi Cement Quarry, in Northeast Libya, it is fossiliferous limestone, consisting of coral, algae, mollusks, and echinoids. The ninth and tenth sections are Quaternary reefs in the Bahamas and the Florida Keys, respectively. These reefs contain a high percentage of coral, red coralline algae, echinoids, mollusks, foraminifers, and ostracods. Based on the data and static analysis results on the thin sections and hand specimens, this study determines the occurrence and outcomes of coral-algal interactions among different coral growth forms (branching, upright, massive, encrusting, plating, and solitary). The Early Paleogene (Paleocene to Eocene) has the highest percentage of algae in two forms (crustose and frondose), which is a good indicator of a warm climate. In the Middle Eocene to Late Eocene, coral replaced algae in different localities in sections of that age. This change is an indicator of climatic cooling, especially in the western Lutetian Darnah section. In the Oligocene time, high-branching corals became abundant and escaped competition with the algae due to Icehouse conditions, as shown in the Al Bayda Formation. In the Miocene, coral species started to decline because of the return to Greenhouse conditions. Coral can lose its competitive edge when chemical and physical defense systems reduce growth and production due to warming. On the other hand, crustose-form algae attract the larvae of the coral. Algae induce them to get a more highly competitive frondose form, which is useful for corals as they decrease growth and production. Algae can quickly colonize the dead reef by using the firm substrate to rebuild themselves. This research may prove valuable when predicting the response of modern coral reef systems to future climatic warming conditions and provides a model for what future reefs may look like.

Frequency dependent polarization analysis of ambient seismic noise recorded at a broadband seismometer in the central United States

We present a new approach to polarization analysis of seismic noise recorded by three-component seismometers. It is based on statistical analysis of frequency-dependent particle motion properties determined from a large number of time windows via eigenanalysis of the 3-by-3, Hermitian, spectral covariance matrix. We applied the algorithm to continuous data recorded in 2009 by the seismic station SLM, located in central North America. A rich variety of noise sources was observed. At low frequencies （〈0.05 Hz） we observed a tilt-related signal that showed some elliptical motion in the horizontal plane. In the microseism band of 0.05-0.25 Hz, we observed Rayleigh energy arriving from the northeast, but with three distinct peaks instead of the classic single and double frequency peaks. At intermediate frequencies of 0.5-2.0 Hz, the noise was dominated by non-fundamental-mode Rayleigh energy, most likely P and Lg waves. At the highest frequencies （〉3 Hz）, Rayleigh-type energy was again dominant in the form of Rg waves created by nearby cultural activities. Analysis of the time dependence of noise power shows that a frequency range of at least 0.02-1.0 Hz （much larger than the microseism band） is sensitive to annual, meteorologically induced sources of noise.

Distribution and Geochemical Characteristics of Hydrogen in Natural Gas from the Jiyang Depression, Eastern China

Hydrogen gas accelerates hydrocarbon generation, but little is known about its distribution and origin in petroliferous basins, which has hindered the further exploration.Taken the Jiyang Depression in eastern China as an example, this study collected natural gas from different tectonic units, and analyzed various geochemical characters including gas contents, and carbon and hydrogen isotopic composition.The result shows that：（1） hydrogen gas is widespread distributed, but its content is very low, which typically ranges from 0.01% to 0.1% in this region;（2） the ratios of H2/3He, indicative of the origins of hydrogen gas, suggest that mantle-derived hydrogen is dominant.Even in tectonically stable areas absent with deep fluid activities, there is also mantle-derived;（3） the isotopic composition of hydrogen falls in the range of –798‰ to –628‰（relative to VSMOW standard）.In areas with deep-derived fluids, the hydrogen gas has a similar isotopic composition with the previously documented deep-sourced gas, with lighter isotopic composition.In contrast, hydrogen gas has a heavier isotopic composition in relatively stable areas.The isotopic signatures suggest that there is a mixture of mantle- and crust-derived hydrogen gas in the relatively stable area, which is consistent with the H2/3He ratios.Therefore, it is clear that the hydrogen gas has a much wider distribution than found in the deep-derived fluid area, resulting in a much broader area with hydrogenating effect for resource rock.This understanding will provide new insights for hydrocarbon generation research and resource assessment in petroliferous basins.

Environmental impact of aquaculture-sedimentation and nutrient loadings from shrimp culture of the southeast coastal region of the Bay of Bengal

Nutrient loadings were measured for surface seawater and bottom sediments of semi intensive and improved extensive shrimp culture pond, adjacent estuary, and fallow land in the south east coastal region of Bangladesh during August, 2000—January, 2001 to evaluate the impact of shrimp culture. The mean levels of nutrients found in the pond surface water were 108 780 mg/L for CaCO 3, 0 526 mg/L for NH + 4 N, 3 075 wt% for organic carbon, 7 00 mg/L for PO 4 P, 5 57 mg/L for NO 3 N, and 7 33 mg/L for chlorophyll a. The maximum mean value of H 2S(0 232 mg/L) was found in estuarine water. Nutrients loading were found to be decreased with distance from the shrimp farm discharge unit in estuarine water. The mean level of organic matter, total nitrogen, and organic carbon were found in higher concentrations in sediments of cultured pond compared to bottom soil of adjacent fallow land at the same elevation. Extractable Ca values were found in higher concentration(550 33 ppt) in adjacent fallow land, as the shrimps for molting in shrimp ponds use extractable Ca. The relation between seawater H 2S value and sediment pH ( r= -0 94); sediment organic carbon and sediment pH values ( r= -0 76), sediment total nitrogen and sediment pH ( r= - 0 74) were found to be highly negatively correlated. Whereas the relation between seawater H 2S value and sediment total nitrogen ( r= 0 92), water NH + 4 N and sediment pH ( r= 0 66) were found to be positively correlated. The results revealed that load of nutrients at eutrophic level in estuarine water, and decrease of soil pH; leading to acid sulphate soil formation indicates a negative impact of shrimp culture.

The Characteristics and Genesis of the Massive Nitrate Deposits in the Turpan-Hami Basin of Xinjiang,China

Massive nitrate deposits have been discovered in the Turpan-Hami basin in northwestern China.Previously,large ore grade nitrate minerals were thought only to exist in the Atacama Desert in northern Chile.Estimates of the

Impacts of Indian summer monsoon and stratospheric intrusion on air pollutants in the inland Tibetan Plateau

Air pollutants can be transported to the pristine regions such as the Tibetan Plateau,by monsoon and stratospheric intrusion.The Tibetan Plateau region has limited local anthropogenic emissions,while this region is influenced strongly by transport of heavy emissions mainly from South Asia.We conducted a comprehensive study on various air pollutants (PM_(2.5),total gaseous mercury,and surface ozone) at Nam Co Station in the inland Tibetan Plateau.Monthly mean PM_(2.5)concentration at Nam Co peaked in April before monsoon season,and decreased during the whole monsoon season (June–September).Monthly mean total gaseous mercury concentrations at Nam Co peaked in July and were in high levels during monsoon season.The Indian summer monsoon acted as a facilitator for transporting gaseous pollutants (total gaseous mercury) but a suppressor for particulate pollutants (PM_(2.5)) during the monsoon season.Different from both PM_(2.5)and total gaseous mercury variabilities,surface ozone concentrations at Nam Co are primarily attributed to stratospheric intrusion of ozone and peaked in May.The effects of the Indian summer monsoon and stratospheric intrusion on air pollutants in the inland Tibetan Plateau are complex and require further studies.

Kyanite far from equilibrium dissolution rate at 0–22℃ and pH of 3.5–7.5

Kyanite is an important and slow-dissolving mineral. Earlier work has measured its dissolution rate at high temperature and acidic pH, but experimental measurements at low temperature and near neutral p H were lacking. The rate equation by Palandri and Kharaka(A compilation of rate parameters of water–mineral interaction kinetics for application to geochemical modeling. US Geological Survey, Open File Report 2004-1068, 2004) indicates that the rate of kyanite dissolution at room temperature and near neutral pH is on the order of 10^-17 mol m^-2 s^-1, orders of magnitudes slower than most common silicate minerals such as albite and quartz. This study used an externallystirred mixed-flow reactor, which allows high solid:solution ratios, to measure the dissolution rate of kyanite at 0–22 ℃ and pH of 3.5–7.5. The measured dissolution rate of kyanite is 4.6–7.6 9 10-13 mol m^-2 s^-1 at 22℃, and the apparent activation energy is 73.5 kJ mol^-1. This dissolution rate is close to the rate of quartz dissolution and four orders of magnitude faster than the prediction by rate equation of Palandri and Kharaka(2004).Based on our new experimental data, we recommend the following rate equation for modeling the dissolution of kyanite at ambient temperatures.r=ke(-Ea)/R(1/T-1/(298.15))where k = 5.08 9 10-13 mol m^-2 s^-1, and Ea= 73.5 kJ mol^-1. Review of literature data(Carroll in The dissolution behavior of corundum, kaolinite, and andalusite: a surface complex reaction model for the dissolution of aluminosilicate minerals in diagenetic and weathering environs. Dissertation, Northwestern University, 1989) led to a recommended rate equation for andalusite as for T = 25℃ and pH = 2–10:r=k1aH+^n1+k2+k3aH^+^n3where k1= 4.04 9 10^-10 mol m^-2 s^-1, k2= 7.95×10^-10 mol m^-2 s^-1, k3= 1.01×10^-17 mol m^-2 s^-1, n1= 1.2 and n3=-0.6.

40^Ar-39^Ar Dating of the Mahuaping W-Be deposit, Northwestern Yunnnan Province, China, and its Geological Significance

Objective Located near the intersection of Yangtze craton, Tibet- Sanjiang orogen and Songpan-Ganzi orogen of Northwest Yunnan Province, the Mahuaping deposit is a unique large -scale tungsten-beryllium-fluorite ore deposit ever discovered in this area. In recent years, many studies have been carried out in Sanjiang Tethyan metallogenic belt and aforementioned adjacent regions. To date, however, little attention has been paid to this deposit, for example, the geochronology of Mahuaping W-Be deposit still remains unsolved. In this study, we have pioneered research about muscovite 40Ar-39Ar age to better understand the geochronology of the Mahuaping W-Be deposit.

Late Cretaceous non-avian dinosaurs from the James Ross Basin,Antarctica:description of new material,updated synthesis,biostratigraphy,and paleobiogeography

Although the fossil record of non-avian dinosaurs from the Cretaceous of Antarctica is the poorest of any continent,fossils representing at least five major taxonomic groups(Ankylosauria,early-diverging Ornithopoda,Hadrosauridae,Titanosauria,and Theropoda)have been recovered.All come from Upper Cretaceous(Coniacian–Maastrichtian)marine and nearshore deposits belonging to the Gustav and Marambio groups of the James Ross Basin at the northern tip of the Antarctic Peninsula.The majority of these finds have come from the Campanian–Maastrichtian Snow Hill Island and López de Bertodano formations of James Ross and Vega islands.Given the rarity of Antarctic Cretaceous non-avian dinosaurs,discoveries of any fossils of these archosaurs,no matter how meager,are of significance.Here we describe fragmentary new ornithischian(ankylosaur and ornithopod)material from the upper Campanian–lower Maastrichtian Cape Lamb Member of the Snow Hill Island Formation and the Maastrichtian Sandwich Bluff Member of the López de Bertodano Formation.One of these specimens is considered to probably pertain to the holotypic individual of the early-diverging ornithopod Morrosaurus antarcticus.We also provide an up-to-date synthesis of the Late Cretaceous non-avian dinosaur record of the James Ross Basin and analyze the biostratigraphic occurrences of the various finds,demonstrating that most(including all named taxa and all reasonably complete skeletons discovered to date)occur within a relatively condensed temporal interval of the late Campanian to early Maastrichtian.Most or all James Ross Basin dinosaurs share close affinities with penecontemporaneous taxa from Patagonia,indicating that at least some continental vertebrates could disperse between southern South America and Antarctica during the final stages of the Mesozoic.

Sedimentology and Ichnology of Upper Montney Formation Tight Gas Reservoir, Northeastern British Columbia, Western Canada Sedimentary Basin

Several decades of conventional oil and gas production in Western Canada Sedimentary Basin (WCSB) have resulted in maturity of the basin, and attention is shifting to alternative hydrocarbon reservoir system, such as tight gas reservoir of the Montney Formation, which consists of siltstone with subordinate interlaminated very fine-grained sandstone. The Montney Formation resource play is one of Canada’s prime unconventional hydrocarbon reservoir, with reserve estimate in British Columbia (Natural Gas reserve = 271 TCF), Liquefied Natural Gas (LNG = 12,647 million barrels), and oil reserve (29 million barrels). Based on sedimentological and ichnological criteria, five lithofacies associations were identified in the study interval: Lithofacies F-1 (organic rich, wavy to parallel laminated, black colored siltstone);Lithofacies F-2 (very fine-grained sandstone interbedded with siltstone);Lithofacies F-3A (bioturbated silty-sandstone attributed to the Skolithos ichnofacies);Lithofacies F-3B (bioturbated siltstone attributed to Cruziana ichnofacies);Lithofacies F-4 (dolomitic, very fine-grained sandstone);and Lithofacies F-5 (massive siltstone). The depositional environments interpreted for the Montney Formation in the study area are lower shoreface through proximal offshore to distal offshore settings. Rock-Eval data (hydrogen Index and Oxygen Index) shows that Montney sediments contains mostly gas prone Type III/IV with subordinate Type II kerogen, TOC ranges from 0.39 - 3.54 wt% with a rare spike of 10.9 wt% TOC along the Montney/Doig boundary. Vitrinite reflectance data and Tmax show that thermal maturity of the Montney Formation is in the realm of “peak gas” generation window. Despite the economic significance of the Montney unconventional “resource-play”, however, the location and predictability of the best reservoir interval remain conjectural in part because the lithologic variability of the optimum reservoir lithologies has not been adequately characterized. This study presents lithofacies and ichnofacies analyses of the Montney Formation coupled with Rock-Eval geochemistry to interpret the sedimentology, ichnology, and reservoir potential of the Montney Formation tight gas reservoir in Fort St. John study area (T86N, R23W and T74N, R13W), northeastern British Columbia, western Canada.

Whole-Rock Geochemistry and Mineralogy of Triassic Montney Formation, Northeastern British Columbia, Western Canada Sedimentary Basin

Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) was used to analyze chemical elements—major, trace and rare earth elements (REE) concentrations, augmented with quantitative X-ray diffraction (XRD) analysis and thin-section petrography for mineralogical characterization of the Triassic Montney Formation in northeastern British Columbia, Western Canada Sedimentary Basin (WCSB). Results from this study indicate that integration of chemical elements with mineralogy shows affinity to the host lithologies. Evidently, chemical elements are the building blocks for minerals, thus, their significances in the interpretation of geological systems are unambiguous. Herein, major elements concentration such as Al, Fe, K, Mg, Ca, Mn in the samples analyzed from the Montney Formation are interpreted as: 1) indication of dolomitization and diagenesis;2) trace elements—Rb, Th, U, and Cs are related to the organic matter—kerogen in the clay component of the Montney Formation source rock;and 3) transition metals—Sc, V, Co, Cr, Zn show strong affinity with diagenesis in the study interval.

Deep Time Reconstructions of Internal Earth Structure with the Adjoint Method

The adjoint method is a powerful tool to obtain gradient information in a computational model relative to unknown model parameters,allowing one to solve inverse problems where analytical solutions are not available or the cost to determine prohibitive.

Nature and source of the ore-forming fluids associated with orogenic gold deposits in the Dharwar Craton

Neoarchean orogenic gold deposits, associated with the greenstone-granite milieus in the Dharwar Craton include(1) the famous Kolar mine and the world class Hutti deposit;(2) small mines at HiraBuddini, Uti, Ajjanahalli, and Guddadarangavanahalli;(3) prospects at Jonnagiri; and(4) old mining camps in the Gadag and Ramagiri-Penakacherla belts. The existing diametric views on the source of ore fluid for formation of these deposits include fluids exsolved from granitic melts and extracted by metamorphic devolatilization of the greenstone sequences. Lode gold mineralization occurs in structurally controlled higher order splays in variety of host rocks such as mafic/felsic greenstones, banded iron formations, volcaniclastic rocks and granitoids. Estimated metamorphic conditions of the greenstones vary from lower greenschist facies to mid-amphibolite facies and mineralizations in all the camps are associated with distinct hydrothermal alterations. Fluid inclusion microthermometric and Raman spectroscopic studies document low salinity aqueous-gaseous(H_2O + CO_2 ± CH_4 + NaCl) ore fluids,which precipitated gold and altered the host rocks in a narrow P-T window of 0.7-2.5 kbar and 215-320℃. While the calculated fluid O-and C-isotopic values are ambiguous, S-isotopic compositions of pyrite-precipitating fluid show distinct craton-scale uniformity in terms of its reduced nature and a suggested crustal sulfur source.Available ages on greenstone metamorphism, granitoid plutonism and mineralization in the Hutti Belt are tantamount, making a geochronology-based resolution of the existing debate on the metamorphic vs.magmatic fluid source impossible. In contrast, tourmaline geochemistry suggests involvement of single fluid in formation of gold mineralization, primarily derived by metamorphic devolatilization of mafic greenstones and interlayered sedimentary rocks, with minor magmatic contributions. Similarly, compositions of scheelite, pyrite and arsenopyrite point toward operation of fault-valves that caused pressure fluctuation-induced fluid phase separation, which acted as the dominant process of gold precipitation,apart from fluid-rock sulfidation reactions. Therefore, results from geochemistry of hydrothermal minerals and those from fluid inclusion microthermometry corroborate in constraining source of ore fluid,nature of gold transport(by Au-bisulfide complex) and mechanism of gold ore formation in the Dharwar Craton.

Seismic interferometry and estimation of the Green's function using Gaussian beams

This study investigates seismic interferometry in which the Green＇s function is estimated between two receiv- ers by cross-correlation and integration over sources. For smoothly varying source strengths, the dominant contributions of the correlation integral come from the stationary phase directions in the forward and backward directions from the alignment of the two receivers. Gaussian beams can be used to evaluate the correlation integral and concentrate the amplitudes in a vicinity of the stationary phase regions instead of completely relying on phase interference. Several numerical examples are shown to illustrate how this process works. The use of Gaussian beams for the evaluation of the correlation integral results in stable estimates, and also provides physical insight into the estimation of the Green＇s function based on seismic interferometry.

Assessment of Acid Deposition Effects on Water Quality of the Upper Rio Grande River Section in Texas

Airborne pollutants such as SO42- and NO3- that cause acid rain may pollute water resources via acid deposition. However, such effects on the water quality of the upper Rio Grande River section in Texas have not been systematically studied. The objective of this study is to collect and analyze field data, and perform hydrological and water chemistry analyses to assess acid deposition effects on the river water quality. The analysis of the precipitation data indicates that the concentrations of ions decrease as the quantity of precipitation increases. The precipitation with higher concentrations of SO42- and NO3- has a lower pH while that with higher concentrations of Ca2+ and Na+ has a relatively higher pH value. The analysis of river data demonstrates that the pH value, Dissolved Oxygen (DO), and Total Dissolved Solid (TDS) generally decrease when the flow rate increases immediately following precipitation events. The drop in pH following a precipitation event is due to the low pH in the precipitation. The DO and TDS decrease after the precipitation due to the increased flow rate. The slightly higher pH and lower DO values in the eastern section of the river (where the basin is limestone-dominated) as compared to the western section is due to the limestone erosion caused by the acid deposition. The annual stone loss by the acid deposition is about 72,000 m3. The fluctuation between the pH value and the temperature suggests the effect of CaCO3 solubility on the pH value. The water chemistry analysis using Geochemist’s Work Bench (GWB) has been performed to estimate the effect on the oscillation of CaCO3 dissolution-precipitation process. The equilibrium pH decreases with decreasing temperature, but increases as the CaCO3 concentration decreases. The effect of limestone on observed daily pH fluctuations appears to be supported by the simulation.

Isotopes (¹³C and ¹⁸O) Geochemistry of Lower Triassic Montney Formation, Northeastern British Columbia, Western Canada

Oxygen isotope (δ18O) serves as paleothermometer, and provides paleotemperature for carbonates. δ18O signature was used to estimate the temperature of fractionation of dolomite and calcite in Montney Formation, empirically calculated to have precipitated, between approximately 13°C to ±33°C during Triassic time in northeastern British Columbia, Western Canada Sedimentary Basin (WCSB). Measurements of stable isotopes (δ13C and δ18O) fractionation, supported by quantitative X-ray diffraction evidence, and whole-rock geochemical characterization of the Triassic Montney Formation indicates the presence of calcite, dolomite, magnesium, carbon and other elements. Results from isotopic signature obtained from bulk calcite and bulk dolomite from this study indicates depleted δ13CPDB (-2.18‰ to -8.46‰) and depleted δ18OPDB (-3.54‰ to -16.15‰), which is interpreted in relation to oxidation of organic matter during diagenesis. Diagenetic modification of dolomitized very fine-grained, silty-sandstone of the Montney Formation may have occurred in stages of progressive oxidation and reduction reactions involving chemical elements such as Fe, which manifest in mineral form as pyrite, particularly, during early burial diagenesis. Such mineralogical changes evident in this study from petrography and SEM, includes cementation, authigenic quartz overgrowth and mineral replacement involving calcite and dolomite, which are typical of diagenesis. High concentration of chemical elements in the Montney Formation?-Ca and Mg indicates dolomitization. It is interpreted herein, that calcite may have been precipitated into the interstitial pore space of the intergranular matrix of very fine-grained silty-sandstone of the Montney Formation as cement by a complex mechanism resulting in the interlocking of grains.

Root Canals and Crowns: An Analysis of the Spatial Distribution of Dental Offices in Ciudad Juárez, Chihuahua, Mexico, 1996-2011

Every city above a certain size has health services that are located, to a large extent, close to their patients. This study analyzes the spatial distribution of dental office and the change in the number of dental offices in Ciudad Juárez, Chihuahua, Mexico over a 15-year time period. Research was conducted in 1996 and 2011. Maps showing the location of dental offices for these two years indicate a clustering of dental offices within one and one-half miles of the city’s two principal border-crossing points between the United States and Mexico. Provider-based surveys were also used to determine the mix of patients (US or Mexican citizens) at the dental offices found throughout the city. By 2011, nearly all of the dental offices clustered within one and one-half miles of the two principal US-Mexico border crossings had 100% of their patients from the United States.

The Utility of 1000 - 500 mb Thickness and Weather Type as a Rain-Snow Divide: A 30-Year Study at Albany, NY

Winter synoptic conditions that produce snowfall with bitterly cold temperatures create both social and economic hazards in the capital city of Albany, NY. Sometimes these systems are forecasted in error to produce rain or mixed precipitation. It is beneficial for meteorologists to better understand the commonly used 5400 and 1300 GPM line to better forecast rain versus snow events. Other studies have looked into the use of the 5400 GPM (540 dm) line but none have assessed the validity of this boundary with respect to weather type characterization at Albany. This study aims to determine the reliability of the widely referenced guides for depicting the rain-snow line, and improve forecast aids for the vertical atmosphere during winter precipitation events. The mean daily 500, 850, 925 and 1000 mb heights and weather type frequency of the Spatial Synoptic Classification between November and March of 1980 - 2012 are analyzed. Results indicate that the standard vertical boundaries are inaccurate indicators of a rain versus snow event in Albany. More reasonable rain-snow cut offs for the 1000 - 500 and 1000 - 850 mb thicknesses are 5222 and 1262 GPM. For the 1000 - 925 mb level, 606 GPM is a helpful aid of identifying the rain-snow boundary. Further scrutinizing by weather type indicates that the rain-snow boundary also varies depending on what air mass/weather type is present on a given day. For instance, when the most prominent weather type is observed over Albany (Dry Polar), at the 1000 - 850 mb and 1000 - 500 mb layers, a boundary of 1242 GPM and 5152 GPM is found to be most representative. Results indicate only for the rarest of winter weather types observed over Albany, Moist Tropical, are the standard cut offs useful. Determining the reliability of this precipitation indicator at a specific station, like Albany, could enable meteorologists in other regions of the country to draw parallels between weather type, precipitation, and thickness in their forecast zones.