Differences In Fluid Composition Research Articles

Investigation the Effect of MR Fluid Composition on Properties at Low Strain Ranges.

The paper presents the results of eight magnetorheological (MR) fluids of different compositions. Magnetite and carbonyl iron were used as magnetic particles. MR fluids based on glycerin and OKS 352 oil were produced using stabilizers in the form of oleic acid and Aerosil 200 (Evonik Resource Efficiency GmbH, Hanau, Germany) silica; additives such as graphite and yellow dextrin were also used. The aim of the study was to determine the properties of various combinations of components on the dynamic properties of MR fluids, i.e., properties characterizing the fluid within the range of low deformations, as well as to investigate the effect of different compositions on structural yield stress and flow stress prepared MR fluids at different magnetic field induction values.

Axisymmetric displacement flows in fluid-driven fractures

Displacement flows are common in hydraulic fracturing, as fracking fluids of different composition are injected sequentially in the fracture. The injection of an immiscible fluid at the centre of a liquid-filled fracture results in the growth of the fracture and the outward displacement of the interface between the two liquids. We study the dynamics of the fluid-driven fracture, which is controlled by the competition between viscous, elastic and toughness-related stresses. We use a model experiment to characterize the dynamics of the fracture for a range of mechanical properties of the fractured material and fracturing fluids. We form the liquid-filled pre-fracture in an elastic brittle matrix of gelatin. The displacing liquid is then injected. We record the radius and aperture of the fracture, and the position of the interface between the two liquids. In a typical experiment, the axisymmetric radial viscous flow is accommodated by the elastic deformation and fracturing of the matrix. We model the coupling between elastic deformation, viscous dissipation and fracture propagation, and recover the two fracturing regimes identified for single-fluid injection. For the viscous-dominated and toughness-dominated regimes, we derive scaling equations that describe the crack growth due to a displacement flow and show the influence of the pre-existing fracture on the crack dynamics through a finite initial volume and an average viscosity of the fluids in the fracture.

Constraints on the formation of carbonates and low‐grade metamorphic phases in the Martian crust as a function of H2O‐CO2 fluids

AbstractLow‐grade metamorphic hydrous minerals and carbonates occur in various settings on Mars and in Martian meteorites. We present constraints on the stability of prehnite, zeolites, serpentine, and carbonates by modeling the influence of H2O‐CO2 fluids during low‐grade metamorphism in the Martian crust using compositions of a Martian basalt and an ultramafic cumulate. In basaltic compositions with 5 wt% fluid, our models predict prehnite in less oxidized, CO2‐poor conditions (≤0.44 mol kg−1 CO2) on warmer geotherms of 20 °C km−1. At fluid‐saturated conditions, epidote and laumontite are replaced by quartz, calcite, chlorite, and muscovite. In ultramafic compositions with 5 wt% fluid, antigorite (serpentine) is stable at CO2‐poor conditions of ≤0.33 mol kg−1, while talc forms at 0.05–0.56 mol kg−1 CO2. At fluid‐saturated conditions, antigorite is replaced by talc and chlorite, and at higher X(CO2) by magnesite and quartz. Our models therefore suggest that prehnite, zeolites, and serpentine have formed in a CO2‐poor environment on Mars implying that fluids during their formation either did not contain high amounts of CO2 or had degassed CO2. Carbonates and potentially talc would have formed in the presence of a CO2‐bearing fluid and therefore at different alteration stages than for prehnite, zeolites, and serpentine either in the same hydrothermal event during which the fluid composition changed gradually due to cooling and precipitation or by separate and successive alteration events with fluids of different compositions.

Behaviour of Titanium Dioxide Particles in Artificial Body Fluids and Human Blood Plasma.

The growing application of materials containing TiO2 particles has led to an increased risk of human exposure, while a gap in knowledge about the possible adverse effects of TiO2 still exists. In this work, TiO2 particles of rutile, anatase, and their commercial mixture were exposed to various environments, including simulated gastric fluids and human blood plasma (both representing in vivo conditions), and media used in in vitro experiments. Simulated body fluids of different compositions, ionic strengths, and pH were used, and the impact of the absence or presence of chosen enzymes was investigated. The physicochemical properties and agglomeration of TiO2 in these media were determined. The time dependent agglomeration of TiO2 related to the type of TiO2, and mainly to the type and composition of the environment that was observed. The presence of enzymes either prevented or promoted TiO2 agglomeration. TiO2 was also observed to exhibit concentration-dependent cytotoxicity. This knowledge about TiO2 behavior in all the abovementioned environments is critical when TiO2 safety is considered, especially with respect to the significant impact of the presence of proteins and size-related cytotoxicity.

Evolution of a hydrothermal ore-forming system recorded by sulfide mineral chemistry: a case study from the Plaka Pb\u2013Zn\u2013Ag Deposit, Lavrion, Greece

Laser ablation-inductively coupled plasma-mass spectrometry and electron-probe microanalysis were used to investigate the trace-element contents of sphalerite, chalcopyrite and pyrite from the Plaka Pb–Zn–Ag deposit. Using petrographic observations, the analytical results could be linked to the temporal evolution of the Plaka ore-forming system. Sphalerite chemistry reliably records the temperature and fS2 evolution of the system, with estimated formation temperatures reproducing the microthermometric results from previous fluid-inclusion studies. Chalcopyrite chemistry also shows systematic variations over time, particularly for Cd, Co, Ge, In, Sn and Zn concentrations. Measurable pyrite was only found in association with early high-temperature mineralisation, and no clear trends could therefore be identified. We note, however, that As and Se contents in pyrite are consistent with formation temperatures estimated from co-existing sphalerite. Statistical analysis of the sphalerite data allowed us to identify the dominant geological controls on its trace-element content. The three investigated factors temperature, fS2, and sample location account for > 80% of the observed variance in Mn, Fe, Co, Ga, Ge, In, Sb and Hg concentrations, and > 60% of the observed variance in Cd and Sn concentrations. Only for Cu and Ag concentrations is the explained variance < 50%. A similarly detailed analysis was not possible for chalcopyrite and pyrite. Nevertheless, comparison of the results for all three investigated minerals indicates that there are some systematic variations across the deposit which may be explained by local differences in fluid composition.

Mud volcanoes in the Gulf of Cadiz as a manifestation of tectonic processes and deep-seated fluid mobilization

Numerous mud volcanoes (MVs) are scattered through the Gulf of Cadiz (GoC), most of which are situated close to the WNW-ESE trending fault system in this region. In this study we have investigated six MVs in locations adjacent to major tectonic lineaments with the purpose of defining fluid and solid mobilization depth and ascent through the accretionary prism. Three of them, R2, D2 and Funky Monkey MVs, were discovered during RV Meteor cruise M149 in 2018. Their morphologies were characterized by multibeam bathymetry and vary from flat-topped to cone-shaped, reflecting different nature of the emitted products and variable degrees of activity. Mud breccias and pore fluids were sampled at the summits of all MVs to determine their physical properties and composition of the solid and liquid fractions. The physical properties and lithological changes demonstrate recent activity of Yuma, Ginsburg, Meknes and Funky Monkey MVs. At these sites, we traced back the origin of venting fluids to clay mineral dehydration through major and minor elements geochemistry, high content of illite in the mud breccia matrix and calculated reaction temperatures of 60–100 °C using the Mg–Li geothermometer. Differences in fluid composition imply a dominant clay dehydration signal in the shallow MVs and a stronger crustal input in the deeper MV (Funky Monkey). In contrast, R2 and D2 MVs are textbook inactive mud domes, showing no venting and a chemical composition/reaction temperature similar to seawater. If crustal input in MVs fluids will be confirmed by subsequent studies (e.g., through Sr isotopes), this could lead to a rethinking of fluid migration in the GoC, where transform faults (and MVs located close to them) focus the crustal signal from depth. Based on the MVs active state and the geochemistry of the fluids, we can distinguish which structure would be more suitable for further analyses (B isotopes, illite crystallinity) in order to identify possible sources of hydrocarbon-rich fluids channeled through MVs. • Six mud volcanoes of the Gulf of Cadiz are described through morphology, sedimentology, mineralogy and geochemistry. • Three new mud volcanoes were discovered during expedition M149 on RV Meteor and hereby characterized for the first time. • Morphology and geochemical signals show marked variations between different parts of the Gulf of Cadiz accretionary prism. • Pronounced crustal input and reduced clay dehydration is present in deeper mud volcanoes located along strike-slip faults.

A hydrothermal apparatus for x-ray absorption spectroscopy of hydrothermal fluids at DESY.

We present a new autoclave that enables in situ characterization of hydrothermal fluids at high pressures and high temperatures at synchrotron x-ray radiation sources. The autoclave has been specifically designed to enable x-ray absorption spectroscopy in fluids with applications to mineral solubility and element speciation analysis in hydrothermal fluids in complex compositions. However, other applications, such as Raman spectroscopy, in high-pressure fluids are also possible with the autoclave. First experiments were run at pressures between 100 and 600 bars and at temperatures between 25 °C and 550 °C, and preliminary results on scheelite dissolution in fluids of different compositions show that the autoclave is well suited to study the behavior of ore-forming metals at P-T conditions relevant to the Earth's crust.

Magnetorheological Fluids Based on Star-Shaped and Linear Polydimethylsiloxanes

Magnetorheological fluids are obtained on the basis of star-shaped and linear PDMS containing 70, 75, and 80 wt % of carbonyl iron microparticles. While pure PDMS polymers are Newtonian fluids, composites exhibit pseudoplasticity. The viscoelastic properties of the obtained magnetorheological fluids of different composition are studied in magnetic fields up to 1 T. The viscosity and storage modulus of the magnetorheological fluids in the maximum magnetic field reach ~0.19–0.65 MPa s and 0.4 MPa, respectively. The relative increase in the viscosity and storage modulus of the magnetorheological fluids based on the star-shaped PDMS with a magnetic filler concentration of 70 wt % in a magnetic field exceeds four orders of magnitude. In the magnetic field, the yield stress of the magnetic composites is as high as 70 kPa at a magnetic field strength of 1 T.

Geochemical signatures of mineralizing events in the Juomasuo Au\u2013Co deposit, Kuusamo belt, northeastern Finland

The Juomasuo Au–Co deposit, currently classified as an orogenic gold deposit with atypical metal association, is located in the Paleoproterozoic Kuusamo belt in northeastern Finland. The volcano-sedimentary sequence that hosts the deposit was intensely altered, deformed, and metamorphosed to greenschist facies during the 1.93–1.76 Ga Svecofennian orogeny. In this study, we investigate the temporal relationship between Co and Au deposition and the relationship of metal enrichment with protolith composition and alteration mineralogy by utilizing lithogeochemical data and petrographic observations. We also investigate the nature of fluids involved in deposit formation based on sulfide trace element and sulfur isotope LA-ICP-MS data together with tourmaline mineral chemistry and boron isotopes. Classification of original protoliths was made on the basis of geochemically immobile elements; recognized lithologies are metasedimentary rocks, mafic, intermediate-composition, and felsic metavolcanic rocks, and an ultramafic sill. The composition of the host rocks does not control the type or intensity of mineralization. Sulfur isotope values (δ34S − 2.6 to + 7.1‰) and trace element data obtained for pyrite, chalcopyrite, and pyrrhotite indicate that the two geochemically distinct Au–Co and Co ore types formed from fluids of different compositions and origins. A reduced, metamorphic fluid was responsible for deposition of the pyrrhotite-dominant, Co-rich ore, whereas a relatively oxidized fluid deposited the pyrite-dominant Au–Co ore. The main alteration and mineralization stages at Juomasuo are as follows: (1) widespread albitization that predates both types of mineralization; (2) stage 1, Co-rich mineralization associated with chlorite (± biotite ± amphibole) alteration; (3) stage 2, Au–Co mineralization related to sericitization. Crystal-chemical compositions for tourmaline suggest the involvement of evaporite-related fluids in formation of the deposit; boron isotope data also allow for this conclusion. Results of our research indicate that the metal association in the Juomasuo Au–Co deposit was formed by spatially coincident and multiple hydrothermal processes.

DEVELOPMENT OF A FIELD MOBILE STANDARD OF THE 2ND CATEGORY AS A TOOL FOR VERIFYING WELL PRODUCTION MEASURING EQUIPMENT

In recent years, in the oil production industry there is a tendency of mass use of stationary multiphase metering units for determining oil, water, and associated gas flow rates in the recoverable well production. Automated group metering units, allowing to cover the whole group of wells in rotation metering mode, became widespread. The necessity of equipping wells with individual or group measuring devices is dictated, first of all, by the economic tasks of improving oil recovery factor and production optimization. In these conditions, the task of periodic verification of stationary measuring devices in the field with the help of mobile standards-measuring devices of higher accuracy class becomes urgent. The standard’s mobility and the need to work in the field with fluids of different composition significantly complicates the task of creating such a device. The practicality and economy of the created units first of all depends on a choice of a measuring method determining the design of the unit. This article analyzes the existing types of equipment for measuring oil, gas, and water consumption at the oil production wells. Showing the main advantages and disadvantages of each of them, this paper proves the necessity of using complex solutions based on different physical principles to improve the accuracy of measurements. The authors have proposed a combined scheme of a mobile standard of the 2nd category with a dynamic method for measuring the phase rates at the core. The unit performs a multi-stage partial separation of the input multiphase flow into liquid and gas phases and determines the fractions of water and oil in the liquid stream using a hydrostatic-type mixture composition analyzer. In addition, this article indicates the ways of increasing the accuracy of the measuring installation.

Synthetic fluid inclusions XXIII. Effect of temperature and fluid composition on rates of serpentinization of olivine

Serpentinization, i.e. the hydrothermal alteration of ultramafic rocks, is an important and ubiquitous geologic process that occurs at slow- and ultraslow-spreading mid-ocean ridges, magma-poor passive margins, and subduction zones. While serpentinization occurs over a wide temperature range and involves diverse fluid compositions, few experimental studies systematically examined the effects of temperature and fluid composition on the kinetics of serpentinization of olivine, and published rates diverge greatly. We present results of an experimental study using synthetic fluid inclusions in Mg-rich olivine as micro-batch reactors to monitor the effects of temperature (100–350 °C), fluid composition (H2O-MgCl-NaCl, H2O-NaCl, H2O-MgCl), and total salinity on serpentinization rates of olivine under closed system conditions.Petrographic observations and Raman analyses of the experimental run products revealed the alteration of olivine to produce serpentine minerals, brucite, and magnetite. The salinity of the aqueous fluid in the inclusions increased as H2O was removed from the solution and incorporated into the hydrous product phases and served as a proxy for reaction progress. The fastest serpentinization rates were found at 250 °C in the presence of a seawater-like aqueous solution. This result further suggests that serpentinization of olivine is fastest at lower temperatures (∼250 °C) and shallower depths in the oceanic lithosphere than suggested by previous studies (∼300 °C). Moreover, our experiments show that serpentinization rates decrease by several orders of magnitude as salinity and the concentration of dissolved Mg increase. These effects may reconcile some of the differences observed when comparing results of previously published rates obtained from experiments involving fluids of different compositions. We constructed a quantitative model based on the principle of detailed balance to predict variations in serpentinization rates (J±) from low temperatures to 320 °C. It suggests that at 25 °C, serpentinization rates are 4 to 5 orders of magnitude slower than at 250 °C. Moreover, the temperature dependence model has been coupled with the kinetic effects derived from experiments involving different fluid composition to calculate the amount of time required for serpentinization of olivine having different reactive surface areas. The model shows that between 200 and 300 °C serpentinization is fast on geologic timescales when rocks with large reactive surface areas interact with a seawater-like aqueous solution (complete serpentinization in days to decades).

Development of a Control Strategy for a Smart Sucker Rod Pump

Summary The sucker-rod pumping (SRP) system is the most used artificial lift method in oil wells in Brazil and in the world. This method stands out for its simplicity and low cost in investments and maintenance, and can be operated in a large range of flow rates, with fluids of different compositions and viscosities. However, the SRP units as well as all other mechanical equipment require periodic adjustments and maintenance, whether corrective or preventive. Two important procedures commonly made at the SRP units are the adjustment for counterbalancing the pumping unit and the adjustment of the polished rod stroke length. Performing these procedures requires stopping the production of the well. Usually, such adjustment procedures are made manually by a work team that is transported to the place where the pumping unit is located. In this context, Petrobras in partnership with Federal University of Rio Grande do Norte and other companies developed a new type of pumping unit, called smart sucker rod pump (SSRP), which is capable of counterbalancing the unit and adjusting the polished rod stroke length without mobilizing a team to go to the field. Thus, this work proposes to develop a strategy to automatically control the SSRP. The development of this strategy aims to ensure that the equipment operates under proper conditions and within its safety limits (previously set by the operator), as well as to optimize the well production. In order to test the control strategy developed for the SSRP, simulations were performed using synthetic wells. It was observed that the developing strategy reached the proposed goals for which it was developed; that is, to keep the parameters of the SSRP within the limits set by the operator and optimize the production flow rate.

Geochemical characteristics of trace occurrences of Mississippi Valley-type mineralization in the U.S. mid-continent: Implications for deposit growth

The Paleozoic strata of the U.S. mid-continent host several major Mississippi Valley-type (MVT) ore deposits and many trace occurrences of MVT mineralization. The present study sought to test the hypothesis that systematic differences in fluid composition led to the differences in scale of mineralization. To conduct this test, fluid inclusions in trace MVT occurrences were characterized and compared to previously characterized fluid inclusions in mid-continent MVT ore deposits.Primary sphalerite-hosted fluid inclusions in trace MVT occurrences from across the U.S. mid-continent were analyzed using microthermometry, Raman spectroscopy, and laser ablation inductively coupled plasma mass spectrometry. Interquartile ranges (25th to 75th percentile) of trace MVT fluid inclusion properties were found to be as follows: homogenization temperature = 78 to 107 °C, salinity = 13.8 to 23.9 equivalent weight percent NaCl, atomic ratios of K/Na = 0.017 to 0.038, Ca/Na = 0.18 to 0.31, Mg/Na = 0.0081 to 0.013, Sr/Na = 0.0093 to 0.015, Ba/Na = 0.00013 to 0.00041. Compared to MVT ore deposits, fluid inclusions in trace MVT occurrences have lower homogenization temperatures and K/Na and Ba/Na ratios, similar salinities and Ca/Na and Sr/Na ratios, and slightly higher Mg/Na ratios (excluding Mg-rich fluid inclusions from the Upper Mississippi Valley district). In addition, fluid inclusions in trace MVT occurrences have low to undetectable methane contents whereas MVT ore deposits have high methane concentrations on the order of 100's to 1000's of ppm. Sphalerite matrix trace metal concentrations of trace MVT occurrences generally overlap those of MVT ore deposits.Differences in elemental concentrations and temperature between trace MVT and MVT ore-forming fluids are insufficient to account for the differences in deposit size. This suggests that differences in the local availability of sulfide, which could not be measured in this study but may correspond with the large observed differences in methane content, may have governed MVT deposit size.

Gold diffusion into and out of quartz-hosted fluid inclusions during re-equilibration experiments at 600–800 °C and 2 kbar

Fluid inclusions were synthesized in quartz and subsequently re-equilibrated in fluids of different compositions to investigate whether the Au content of fluid inclusions can be modified via Au diffusion through the host quartz. In one experiment fluid inclusions containing 5wt% KCl were synthesized in platinum capsules at 2kbar, 800°C and then re-equilibrated at the same conditions for 4days in a fluid containing 20.1wt% NaCl, 3.5wt% HCl and ~100ppm Cs enclosed in a gold capsule. LA-ICP-MS analyses of 5–10 fluid inclusions before and after the re-equilibration experiment demonstrate that the inclusions gained up to 570ppm Au and up to 0.23wt% Na during the re-equilibration process. Their unchanged high K-content and the absence of Cs within the inclusions proves that they remained physically closed during the re-equilibration, and thus that Na and Au were gained by diffusion through the quartz lattice. In a similar experiment conducted at 600°C the fluid inclusions gained up to 140ppm Au within 14days. Reverse experiments were conducted by synthesizing Au-bearing fluid inclusions in gold capsules and then re-equilibrating them in platinum capsules, which caused the inclusions to lose up to several hundred ppm Au. In both type of experiments Au diffusion appears to have been driven by chemical potential gradients of Au between the fluid inclusions and the external fluid. Additional experiments were performed to test whether Au is able to diffuse into fluid inclusions in response to loss of H+, or indirectly as a consequence of diffusional Cu-gain and corresponding formation of Cu-rich sulfide daughter crystals. However no evidence for Au uptake via such mechanisms was found.If Au concentrations in natural, quartz-hosted fluid inclusions from magmatic-hydrothermal ore deposits are affected, then they likely lost Au rather than gained it. At temperatures below 400°C diffusional loss or gain of Au is considered unlikely in magmatic-hydrothermal systems, but potentially was significant in samples from orogenic Au gold deposits.

Calculating thermophysical fluid properties during geothermal energy production with NESS and Reaktoro

We investigate how subsurface fluids of different compositions affect the electricity generation of geothermal power plants. First, we outline a numerical model capable of accounting for the thermophysical properties of geothermal fluids of arbitrary composition within simulations of geothermal power production. The behavior of brines with varying compositions from geothermal sites around the globe are then examined using the model. The effect of each brine on an idealized binary geothermal power plant is simulated, and their performances compared by calculating the amount of heat exchanged from the fluid to the plant's secondary cycle.Our simulations combine (1) a newly developed Non-linear Equation System Solver (NESS), for simulating individual geothermal power plant components, (2) the advanced geochemical speciation solver, Reaktoro, used for calculation of thermodynamic fluid properties, and (3) compositional models for the calculation of fluid-dynamical properties (e.g., viscosity as a function of temperature and brine composition). The accuracy of the model is verified by comparing its predictions with experimental data from single-salt, binary-salt, and multiple-salt solutions.The geothermal power plant simulations show that the brines considered in this study can be divided into three main categories: (1) those of largely meteoric origin with low salinity for which the effect of salt concentration is negligible; (2) moderate-depth brines with high concentrations of Na+ and K+ ions, whose performance is well approximated by pure NaCl solutions of equivalent salinity; and (3) deeper, high-salinity brines that require a more detailed consideration of their composition for accurate simulation of plant operations.

Uranium-bearing opals: Products of U-mobilization, diffusion, and transformation processes

Understanding the retention mechanism of U by amorphous silica (i.e., opal) in the environment is of great importance to nuclear-waste disposal because opals can retain U for millions of years. Uraniferous opals from Spor Mountain and the Thomas Range, Utah, U.S.A., are examined in terms of their mineralogical, chemical, and isotopic compositions. Uranium-rich zones composed of most likely vorlanite, CaUO 4 , occur in fibrous opal-CT (termed lussatite) along the interface of the phase with microcrystalline quartz. Red- to black-colored precipitates of vorlanite also occur in the interstices between fibers and grains in lussatite and massy opals, respectively. The high abundance of vorlanite in certain growth zones can be explained by the diffusion of Ca and U along boundaries of layers, grains, and fibers and by the release of Ca and U through the transformation of opal-A into opal-CT and from opal-CT into microcrystalline quartz. Similar O-isotope compositions of opal-CT and associated microcrystalline quartz indicate that crystallization processes and deposition of subsequent layers of opal occurred from fluids of similar origin and T . Differences in the isotope and chemical composition between uraniferous opals/microcrystalline quartz, the SiO 2 polymorph moganite, and pyrolusite indicate the past occurrence of various alteration processes involving fluids of different composition and T . The results of this study indicate that assemblages of opal and microcrystalline quartz can retain U for millions of years as long as confined pore spaces between different generations of opal and quartz or between growth features of opal provide space for the nucleation and adsorption of U-bearing phases and species.

Mineralogy and stratigraphy of the Gale crater rim, wall, and floor units

AbstractThe Curiosity rover has detected diverse lithologies in float rocks and sedimentary units on the Gale crater floor, interpreted to have been transported from the rim. To understand their provenance, we examine the mineralogy and geology of Gale's rim, walls, and floor, using high‐resolution imagery and infrared spectra. While no significant differences in bedrock spectral properties were observed within most Thermal Emission Imaging System and Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) scenes, some CRISM scenes of rim and wall rocks showed olivine‐bearing bedrock accompanied by Fe/Mg phyllosilicates. Hydrated materials with 2.48 μm absorptions in Gale's eastern walls are spectrally similar to the sulfate unit in Mount Sharp (Aeolis Mons). Sedimentary strata on the Gale floor southwest of the landing site, likely coeval with the Bradbury units explored by Curiosity, also are hydrated and/or have Fe/Mg phyllosilicates. Spectral properties of these phyllosilicates differ from the Al‐substituted nontronite detected by CRISM in Mount Sharp, suggesting formation by fluids of different composition. Geologic mapping of the crater floor shows that the hydrated or hydroxylated materials are typically overlain by spectrally undistinctive, erosionally resistant, cliff‐forming units. Additionally, a 4 km impact crater exposes &gt;250 m of the Gale floor, including finely layered units. No basement rocks are exposed, thus indicating sedimentary deposits ≥250 m beneath strata studied by Curiosity. Collectively, the data indicate substantial sedimentary infill of Gale crater, including some materials derived from the crater rim. Lowermost thin layers are consistent with deposition in a lacustrine environment; interbedded hydrated/hydroxylated units may signify changing environmental conditions, perhaps in a drying or episodically dry lake bed.

Sulfate brines in fluid inclusions of hydrothermal veins: Compositional determinations in the system H2O-Na-Ca-Cl-SO4

Sulfate is among the most abundant ions in seawater and sulfate-bearing brines are common in sedimentary basins, among other environments. However, the properties of sulfate-bearing fluid inclusions during microthermometry are as yet poorly constrained, restricting the interpretation of fluid-inclusion compositions where sulfate is a major ion. The Schwarzwald mining district on the eastern shoulder of the Upper Rhinegraben rift is an example of a geologic system characterized by sulfate-bearing brines, and constraints on the anion abundances (chloride versus sulfate) would be desirable as a potential means to differentiate fluid sources in hydrothermal veins in these regions. Here, we use the Pitzer-type formalism to calculate equilibrium conditions along the vapor-saturated liquidus of the system H2O-Na-Ca-Cl-SO4, and construct phase diagrams displaying the predicted phase equilibria. We combine these predicted phase relations with microthermometric and crush-leach analyses of fluid inclusions from veins in the Schwarzwald and Upper Rhinegraben, to estimate the compositions of these brines in terms of bulk salinity as well as cation and anion loads (sodium versus calcium, and chloride versus sulfate). These data indicate systematic differences in fluid compositions recorded by fluid inclusions, and demonstrate the application of detailed low-temperature microthermometry to determine compositions of sulfate-bearing brines. Thus, these data provide new constraints on fluid sources and paleo-hydrology of these classic basin-hosted ore-forming systems. Moreover, the phase diagrams presented herein can be applied directly to compositional determinations in other systems.

Laboratory measurements of nitrogen dissolution in Titan lake fluids

We obtained laboratory measurements of nitrogen solubility in mixed solutions of ethane and methane at temperatures and pressures relevant to Titan's lakes and seas. Our results show that nitrogen solubility is increased at higher methane concentration, lower temperature, and higher pressure. We developed an empirical fit that agrees well with our measurements. We show that significant volumes of nitrogen gas will be released from Titan lake fluids on heating, and that significant volumes of nitrogen gas will be absorbed by Titan lake fluids on cooling. The densities of the lake fluids will be affected by nitrogen dissolution. We also show that mixing of two cryogenic fluids of different composition can lead to the release of large amounts of nitrogen gas. This has implications for lake fluids, bubble formation, geological phenomena, and also for future landed missions on the surface of Titan. We find in particular that methane-rich lakes at lower temperatures on Titan will be the most sensitive to changes in surface conditions, either cooling, heating, or compositional mixing.

The Differentiation of Menstrual from Venous Blood and Other Body Fluids on Various Substrates Using ATR FT-IR Spectroscopy.

Crime scene investigators and laboratory analysts use chemical tests to detect and differentiate body fluids. Testing often requires a sample of the stain, and the chemicals may cause degradation of the fluid or interfere with subsequent tests. Colorimetric chemical tests do not differentiate between different types of the same fluid, such as venous and menstrual blood, and there is no presumptive test available to simultaneously differentiate several body fluids. In this study, we recorded ATR FT-IR spectra of venous and menstrual blood, semen, saliva, and breastmilk. Neat and simulated casework body fluid samples were analyzed on cotton, nylon, wood, paper, and glass substrates. Differences in fluid composition, including proteins and small molecules, resulted in spectral differences. Venous and menstrual blood is differentiated by the peak at 1039cm-1 attributed to phosphoric acid found in menstrual blood. Peak intensity is influenced by the porosity and weave of the substrate fabric.