Pyrogenic dissolved organic matter (pyDOM) is known to be an important biogeochemical constituent of aquatic ecosystems and the carbon cycle. While our knowledge of pyDOM’s production, composition, and photolability has been studied recently, we lack an understanding of potential microbial mineralization and transformation of pyDOM in the biogeosphere. Thus, leachates of oak charred at 400 and 650 °C, as well as their photodegraded counterparts, were incubated with a soil-extracted microbial consortium for up to 96 days. Over the incubation, significantly more carbon was biomineralized from the lower versus higher temperature char leachate (45% versus 37% lost, respectively). Further, the photodegraded leachates were biomineralized to significantly greater extents than their fresh non-photodegraded counterparts. Kinetic modeling identified the mineralizable pyDOC fractions to have half-lives of 9 to 13 days. Proton nuclear magnetic resonance spectroscopy indicated that the majority of this loss could be attributed to low molecular weight constituents of pyDOM (i.e., simple alcohols and acids). Further, quantification of benzenepolycarboxylic acid molecular markers indicated that condensed aromatic compounds in pyDOM were biomineralized to much less extents (4.4 and 10.1% decrease in yields of ΣBPCA-C over 66 days from Oak-400 and Oak-650 pyDOM, respectively), but most of this loss could be attributed to biomineralization of smaller condensed clusters (4 aromatic rings or less). These results highlight the contrasting bioavailability of different portions of pyDOM and the need to examine both to evaluate its role in aquatic heterotrophy and its environmental fate in the hydrogeosphere.

Processes and timescales of magmas: U-series, 40Ar/39Ar chronology, and ternary feldspars, for the Quaternary Suswa volcano, Central Kenya Peralkaline Province, East African Rift Vanessa V. Espejel-García a, Elizabeth Y. Anthony b, Peter A. Omenda c, Alan L. Deino d, John C. White e a Facultad de Ingeniería, Universidad Autónoma de Chihuahua, Circuito No. 1, Campus Universitario 2, C.P. 31125, Chihuahua, Chih., México. b University of Texas at El Paso, El Paso, TX 79968, USA c Scientific and Engineering Power Consultants, P.0. Box 38991, Nairobi, Kenya d Berkeley Geochronology Center, Ridge Road, Berkeley, CA, 94709, USA. e Eastern Kentucky University, Richmond, KY 40475, USA Corresponding author. Vanessa V. Espejel-García, vespejel@uach.mx, Tel. (52) 614 221 7549. ORCID a 0000-0002-0486-8726 b 0000-0001-7951-1724 c —- d 0000-0002-0099-9382 e 0000-0001-5107-6847 Suswa is a Late Pleistocene to recent volcano in the axis of the East African Rift. Early activity saw construction of a trachytic shield volcano, followed by mafic-felsic magma mixing, explosive volcanism, and caldera collapse. Recent activity includes drawn down of the magma chamber to create a second, inner caldera, a resurgent dome, and eruption of phonolites (White et al., 2012, Lithos, 152, 88-104). 40Ar/39Ar ages for the initial shield volcano are ca. 110 ka. Formation of the outer caldera occurred at ca. 46 ka, and initial post-caldera eruptions followed soon thereafter at 32.5 ka. Final eruptions are ca. 11 ka to “zero age”. 230Th/232Th confirms simultaneity of mafic eruptions in the peripheral fields and the youthfulness of the final events. The 203Th/232Th data also demonstrate that depth for initial magma generation lies below the spinel peridotite field within garnet peridotite. Ground deformation includes deflation of 4.6 cm from 1997 to 2000 (Biggs et al., 2009) and subsequent inflation of 4.3 +/- 0.8 cm/yr from 2015 to 2020 (Albino and Biggs, 2021, G3). Alkali feldspar from pre- and most syn-caldera has a limited compositional range. Feldspars in mingled lavas include bimodal distribution of these alkali feldspar and plagioclase identical in composition to similar-age cinder cones and fissure flows adjacent to the volcano. Alkali feldspar shifts to greater An content in the post-caldera phonolite. Oscillatory and tabular textures record rapid crystal growth and turbulence in the phonolite magma chamber. However, neither the textures nor the composition range necessitate renewed addition of mafic material.

Deep-sea δ18O records show a pronounced difference in Milankovitch periodicity between the Early and Late Pleistocene. δ18O is interpreted as a proxy for ice sheet volume and temperature, which led to the conclusion that glacial-interglacial cycles considerably changed their rhythm during the mid-Pleistocene. This transition is referred to as the mid-Pleistocene Transition (MPT). Specifically, the precessional component of the Milankovitch cycles is absent in Early Pleistocene δ18O records, despite its continuous presence in solar insolation forcing to the ice sheets. Climate feedbacks involving (sea) ice, geological processes and carbon and nutrient cycling have been proposed as causes of this marked change. We however show that the absence of an Early Pleistocene precession signal in deep-sea δ18O records could be the result of destructive interference of the precessional cycle in the interior ocean. Such cancellation is caused by the anti-phasing of the precessional cycle between the North Atlantic and Southern Ocean deep-water sources (see Figure). We explore the potential for cancellation in the transient setup of the Total Matrix Intercomparison model for a wide range of source signal strengths. Our results show that cancellation can cause the absence of the precessional signal due to cancellation in the interior South-Atlantic, Indian and Pacific basins. Cancellation is especially widespread for a relative end-member contribution typical for the Early Pleistocene. We therefore conclude that the precessional component is likely incompletely archived in Early Pleistocene δ18O records, and appears as an actual change in Milankovitch periodicity across the MPT. Proxies not susceptible to cancellation of precession (such as those currently retrieved across the MPT from Antarctica) would be able to verify to what extent deep-sea δ18O correctly represents Pleistocene climate.

In situ measurements of the seasonal cycle of δ13C(CO2) provide complementary information on the seasonality of the global carbon cycle, but are currently not exploited in the context of process-based carbon cycle models. We use isotope-enabled simulations of the Bern3D-LPX Earth System Model of Intermediate Complexity and fossil fuel emission estimates together with a model of atmospheric transport to simulate local atmospheric δ13C(CO2). We find good agreement between the measured and simulated seasonal cycle of atmospheric δ13C(CO2) (mean seasonal amplitude mismatch of 0.02 ‰ across 19 sites), particularly at high northern latitude sites. Factorial simulations reveal that the seasonal cycle of δ13C(CO2) is primarily driven by land biosphere carbon exchange. Spatial and temporal fluxes of CO2 and their signatures are analyzed to quantify the terrestrial drivers. The influence of external forcings (climate and land use change) on seasonal amplitude is found to be small. Unlike the growth of seasonal amplitude of CO2, no consistent change in seasonal amplitude of δ13C(CO2) is simulated over the historical period, nor evident in the available observations. We conclude that the seasonal cycle of δ13C(CO2) is influenced by different carbon cycle processes, and its potential as a novel atmospheric constraint should be further explored.

Cosmogenic exposure data can be used to calculate time-varying fault slip rates on normal faults with exposed bedrock scarps. However, the method relies on assumptions related to how the scarp is preserved, which should be consistent at multiple locations along the same fault. Previous work commonly relied on cosmogenic data from a single sample locality to determine the slip rate of a fault. Here we show that by applying strict sampling criteria and using geologically informed modelling parameters in a Bayesian-inference Markov chain Monte Carlo method, similar patterns of slip rate changes can be modelled at multiple sites on the same fault. Consequently, cosmogenic data can be used to resolve along-strike fault activity. We present cosmogenic 36Cl concentrations from seven sites on two faults in the Italian Apennines. The average slip rate varies between sites on the Campo Felice Fault (0.84 0.23 to 1.61 0.27 mm yr ^-1), and all sites experienced a period of higher than average slip rate between 0.5 and 2 ky and a period of lower than average slip rate before 3 ky. On the Roccapreturo fault, slip rate in the centre of the fault is 0.550.11 and 0.350.05 mm yr ^-1 at the fault tip near a relay. The estimated time since the last earthquake is the same at each site along the same fault. These results highlight the potential for cosmogenic exposure data to reveal the detailed millennial history of earthquake slip on active normal faults.

IDN Penelitian ini dilakukan dengan tujuan untuk memetakan pola aliran air tanah di sekitar Kali Sumpil di wilayah Kota Malang. Lokasi penelitian ini adalah di segmen Kali Sumpil sepanjang 5,6 km yang mengalir mulai dari Kecamatan Lowokwaru hingga ke pertemuan antara Kali Sumpil dan Kali Sari di Kecamatan Blimbing, Kota Malang. Pola aliran air tanah di lokasi penelitian dipetakan berdasarkan elevasi muka air tanah yang diukur dari 43 lokasi sumur gali milik warga yang tersebar di sepanjang aliran Kali Sumpil tersebut. Elevasi muka air tanah pada sumur gali warga di lokasi penelitian berkisar antara +493,88 m dpl di bagian hulu hingga +436,70 m dpl di bagian hilir. Elevasi muka air tanah tertinggi berada pada sumur gali SG-26 yang berada di sebelah kanan aliran bagian hulu Kali Sumpil, sedangkan elevasi muka air tanah terendah berada pada sumur gali SG-25 di sebelah kiri aliran bagian hilir Kali Sumpil. Secara umum, aliran air tanah di lokasi penelitian mengalir dari arah Barat Laut menuju ke arah Tenggara bersesuaian dengan arah aliran Kali Sumpil. Hubungan antara air tanah dan air permukaan adalah air tanah mengisi air permukaan Kali Sumpil. EN The objective of this study is to mapping the groundwater flow patterns around Sumpil River in Malang City. The location of this study is in one of the segments of Sumpil River along the 5.6 km which flows from Lowokwaru District to the confluence of Sumpil River and Sari River in Blimbing District, Malang City. The groundwater flow pattern in the area of the study was mapped based on the groundwater level measured from 43 resident’s dug wells scattered along Sumpil River. The groundwater level in the area of the study ranges from +493,88 m asl in the upstream area to +436,70 m asl in the downstream area. The highest groundwater level is in the SG-26 which is located to the right of the upstream flow of the Sumpil River, while the lowest groundwater level is in the SG-25 to the left of the downstream flow of the Sumpil River. In general, groundwater flow in the area of study flows from the Northwest to the Southeast in accordance with the direction of the Sumpil River flow. The interaction between groundwater and surface water is the groundwater flows to Sumpil River (gaining stream).

Stable water isotopologues tend to fractionate from ordinary water during evaporation processes resulting in an enrichment of the isotopic species in the soil. The fractionation process can be split into equilibrium fractionation and kinetic fractionation. Due to the complex coupled processes involved in simulating soil-water evaporation accurately, defining the kinetic fractionation correctly remains an open research area. In this work, we present a multi-phase multi-component transport model that resolves flow through both the near surface atmosphere and the soil, and models transport and fractionation of the stable water isotopologues using the numerical simulation environment DuMuX. Using this high resolution coupled model, we simulate transport and fractionation processes of stable water isotopologues in soils and the atmosphere without further parameterization of the kinetic fractionation process as is commonly done. In a series of examples, the transport and distribution of stable-water isotopologues are evaluated numerically with varied conditions and assumptions. First, an unsaturated porous medium connected to constant laminar flow conditions is introduced. The expected vertical isotope profiles in the soil as described in literature are reproduced. Further, by examining the spatial and temporal distribution of the isotopic composition, is determined the enrichment of the isotopologues in soil is linked with the different stages of the evaporation process. Building on these results, the robustness of the isotopic fractionation in our model is analysed by isolating single fractionation parameters. The effect of wind velocity and turbulent atmospheric conditions is investigated, leading to different kinetic fractionation scenarios and varied isotopic compositions in the soil.

Arctic sea ice cover has been steeply declining since the onset of satellite observations in the late 1970s. However, the available annually resolved sea ice data prior to this time are limited. Here, we evaluated the suitability of annual trace element (Mg/Ca) ratios and growth increments from the long-lived annual increment-forming benthic coralline red alga, Clathromorphum compactum, as high-resolution sea ice cover c. It has previously been shown that growth and Mg/Ca of C. compactum are strongly light controlled and therefore greatly limited during polar night and underneath sea ice cover. We compare algal data from 11 sites collected throughout the Canadian Arctic, Greenland and Svalbard, with satellite sea ice data. Our results suggested that algal growth anomalies most often produced better correlations to sea ice concentration than Mg/Ca alone or when averaging growth and Mg/Ca anomalies. High Arctic regions with persistently higher sea ice concentrations and shorter ice-free seasons showed strongest correlations between algal growth anomalies and satellite sea ice concentration over the study period (1979-2015). At sites where ice breakup took place prior to the return of sufficient solar irradiance, algal growth was most strongly tied to a combination of solar irradiance and other factors such as temperature, suspended sediments, phytoplankton blooms and cloud cover. These data are the only annually resolved in situ marine proxy data known to date and are of utmost important to gain a better understanding of the sea ice system and to project future sea ice conditions.

10 Techniques for fast large-volume sampling of total gaseous mercury (TGM) in the air 11 and extracting the TGM with 5 mL acid solution were developed for stable mercury 12 isotope ratio measurements. A Big gold coated sand Trap (BAuT), a 45 mm i.d. × 300 13 mm length quartz tube containing 131 times more gold coated silica than a conventional 14 gold trap has, was used for the collection of a large amount of TGM from the air. The 15 collected TGM was then extracted by 5 mL reversed aqua resia in a 2L Tedler bag, and 16 the extract was analyzed by a cold-vapor generator coupled with a multi collector 17 inductively coupled plasma mass spectrometer for the isotopic compositions. The 18 sampling tests of BAuT showed 99.9% or higher collection efficiency during the 19 sampling time of 1-24 h under the flow rate of 20-100 L min-1. Recovery tests of the 20 bag extraction using 100 ng of NIST SRM 8610 exhibited nearly 100% of recovery 21 yields and agreement of the measured five stable mercury isotope ratios with the 22 reference values within 2  of uncertainty when using the trapping solution of 40% 23 reversed aqua resia with the extraction time of a day. The overall methodology tested in 24 the pilot field and laboratory studies demonstrated the successful analysis, promising 25 highly precise stable mercury isotopic data with the time resolution less than a day. Part 26 of the procedure can be automated, ideal for unmanned sampling at a remote site.

Studies reconstructing surface paleoproductivity and benthic conditions allow us to measure the effectiveness of the biological pump, an important mechanism in the global climate system. In order to assess surface productivity changes and their effect on the seafloor, we studied the core SAT-048A, recovered from the continental slope of the southernmost Brazilian continental margin, in the western South Atlantic. We assessed the sea surface productivity, the organic matter flux to the seafloor and the dissolution effects, based on micropaleontological (benthic and planktonic foraminifers, ostracods), geochemical (benthic and planktonic δ13C isotopes) and sedimentological data (carbonate and bulk sand content). Superimposed on the climate-induced changes related to the last glacial-interglacial transition, the reconstruction indicates paleoproductivity changes synchronized with the precessional cycle. From the reconstructed data, it was possible to identify high (low) surface productivity, high (low) organic matter flux to the seafloor, and high (low) dissolution rates of planktonic Foraminifera tests during the glacial (postglacial). Furthermore, within the glacial, enhanced productivity was associated with higher insolation values, explained by increased NE summer winds that promoted meandering and upwelling of the nutrient-rich South Atlantic Central Water. Changes in the Atlantic Meridional Overturning Circulation and the reorganization of bottom water masses could also have changed the CO3 2- saturation levels and have influenced the carbonate preservation. However, changes in the Uvigerina spp. δ13C values are very likely linked to the organic matter flux and not to the sea bottom dissolved inorganic matter δ13C values.

Parental melt compositions of poikilitic shergottites exhibit similar compositions to that of olivine-phyric shergottites, possibly linking them.

Martian dust, which likely formed by non-aqueous chemical weathering [Huguenin, 1976] following broad-based support from recent Mars mission data, is susceptible to rapid diagenesis when exposed to macro-seepage from the sub-permafrost aqueous aquifer system on Mars . The modeled silicate components of the dust, derived from the non-aqueous weathering of primarily olivine and pyroxene, are Mg2HSiO4(OH) and Mg(HSiO3)(OH). These are M-S-H compounds, counterparts to the C-H-S compounds that form the commercial binder in concrete, forming an Mg3Si2O5(OH)4 counterpart binder on Mars upon exposure to liquid H2O macro-seepage from the aquifer below. Macro-seepage, triggered largely by geothermally heated water near impact sites, magmatic intrusions and volcanoes, is proposed to rapidly cement layers of regolith dust and fines into layers of M-S-H counterpart “concrete.” The matrix binder on Mars is predicted to be a member of the serpentine family (Mg/Si = 5), possibly having disordered Antigorite T structure. Layered sedimentary rock formations could have formed throughout geologic history up to the present time. Materials from the aquifer, transported by and introduced from the macro-seepage, including organic matter, may be contemporary rather than ancient. This contradicts the prevailing assumption that the sedimentary rocks were formed early in the planet’s history.

Planktonic Foraminifera are widely used for environmental reconstructions through measurements of their shell’s geochemical characteristics, including its stable oxygen and carbon isotope composition. Using these parameters as unbiased proxies requires a firm knowledge of all potential confounding factors influencing foraminiferal shell geochemistry. One such parameter is the shell calcification intensity (shell weight normalized for shell size) that may influence the shell δ18O value either bioenergetically (by reducing energy available and required for equilibrium isotope fractionation during faster calcification) or kinetically (by influencing calcification depth through the shell’s density contrast with seawater). Specimens from the Globigerinoides ruber/elongatus compound from a sediment trap in the North Atlantic have been used to quantify the influence of shell calcification intensity on shell δ18O values. Shell calcification intensity was found to have a significant effect on the shell stable oxygen isotope composition in all species. Through model fitting, it is suggested that the effect size may be in a range of 1 to 2‰ (depending on species, depth migration, and local oceanographic conditions). We show that the confounding effect of shell calcification intensity on stable oxygen isotope composition can be of importance, depending on the anticipated precision of the derived reconstructions. A framework is provided to quantify this effect in future studies.

Apatite (U-Th)/He (AHe) dating is a widely-applied thermochronological technique used to decipher low-temperature thermal histories. Accurate dates require that the results are corrected for α-ejection because 4He atoms travel ~20 µm during α-decay and a correction is required to account for He lost by this effect. Effective uranium concentrations (eU) are important for accurate AHe data interpretation because radiation damage scales with eU, which affects He retentivity. Both α-ejection correction parameter (Ft) and eU are calculated on the basis of crystal size and assuming an idealized morphology. However, the uncertainty stemming from the calculations’ assumptions depends on how much the real crystal geometry deviates from that assumed, and this uncertainty is typically not included in the propagated uncertainties on AHe data. Our goal for this study was to develop a ‘rule of thumb’ for Ft and eU uncertainties associated with the full range of commonly analyzed apatite geometries by comparing manually measured grain size and actual grain size using nano-computed tomography (nano-CT). Apatite geometry and roughness were characterized using a Grain Evaluation Matrix (GEM). The geometry of each grain was described as: A (prismatic/hexagonal), B (subprismatic), or C (rounded/ellipsoid). Surface roughness was graded from ‘least’ to ‘most’ using values from 1 to 3. The GEM allows for a single parameter (eg. B2) to succinctly classify a grain’s morphology. High resolution nano-CT scans of ~260 grains representative of those usually analyzed for AHe dates were completed and processed using Dragonfly and Blob3D. Initial analysis shows that manual grain measurements systematically overestimate the actual grain size, leading to overestimates in Ft and eU values. One correction exists for A and B grains (hexagonal) and another for C grains (ellipsoid). The correction is controlled primarily by grain size and shape, while the uncertainty on the correction appears to be controlled primarily by surface roughness. Together, this approach provides a simple and practical tool for deriving more accurate Ft and concentration values, and for incorporating this oft neglected geometric uncertainty into AHe dates.

Many intermediate to felsic intrusive and extrusive rocks contain mafic magmatic enclaves that are evidence for magma recharge and mixing. Whether enclaves represent records of pro-longed mixing or syn-eruptive recharge depends on their preservation potential in their intermediate to felsic host magmas. We present a model for enclave consumption where an initial stage of diffusive equilibration loosens the crystal framework in the enclave followed by advective erosion and disaggregation of the loose crystal layer. Using experimental data to constrain the propagation rate of the loosening front leads to enclave “erosion” rates of 10-5 to 10-8 cm/s for subvolcanic magma systems. These rates suggest that under some circumstances, enclave records are restricted to syn-eruptive processes, while in most cases enclave populations represent the recharge history over centuries to millennia. On these timescales mafic magmatic enclaves may be unique recorders that can be compared to societal and written records of volcano activity.

Combing geochemical and seismological results constrains the composition of the middle and lower continental crust better than either field can achieve alone. The inaccessible nature of the deep crust (typically >15 km) forces reliance on analogue samples and modeling results to interpret its bulk composition, evolution, and physical properties. A common practice relates major oxide compositions of small- to medium-scale samples (e.g. medium to high metamorphic grade terrains and xenoliths) to large scale measurements of seismic velocities (Vp, Vs, Vp/Vs) to determine the composition of the deep crust. We provide a framework for building crustal models with multidisciplinary constraints on composition. We present a global deep crustal model that documents compositional changes with depth and accounts for uncertainties in Moho depth, temperature, and physical and chemical properties. Our 3D deep crust global compositional model uses the USGS global seismic database (Mooney, 2015) and a compilation of geochemical analyses on amphibolite and granulite facies lithologies (Sammon McDonough, 2021). We find a compositional gradient from 61.2 ± 7.3 to 53.8 ± 3.0 wt.% SiO2 from the middle to the base of the crust, with the equivalent lithological gradient ranging from quartz monzonite to gabbronorite. In addition, we calculate trace element abundances as a function of depth from their relationships to major oxides. From here, other lithospheric properties, such as Moho heat flux, are derived (18.8 ± 8.8 mW/m2). This study provides a global assessment of major element composition in the deep continental crust.

The HighPGibbs program is designed to calculate thermodynamic equilibrium of fluid-rock minerals and solid solutions up to depths of lithospheric mantle. It uses the Gibbs free energy minimization function of the HCh package to calculate mineral-fluid equilibrium assemblages. Chemical potentials of minerals are calculated using the equations of states included in HCh; free energy of aqueous species are calculated using the Deep Earth Water model; and activity coefficients of charged species are estimated using the Davies variant of the Debye-Hückel equation. HighPGibbs was applied to calculate nitrogen speciation in eclogite-buffered fluids from 400 to 790 °C and 30 to 54 kbar, to evaluate the mobility of nitrogen in subducting oceanic crust. Regardless of whether the protolith was altered (and oxidized) or not, N(aq) or NH(aq) are the predominant form of nitrogen in the slab-fluids at sub-arc temperatures, especially in cases of moderate or hot geotherms. Given that molecular nitrogen is highly incompatible in silicate minerals, the simulation indicates that nitrogen (as NH) in silicate minerals can be liberated during metamorphic devolatilization. The majority of nitrogen in subducting crusts can be unlocked during slab devolatilization and eventually expelled to the atmosphere via degassing of arc magmas. Therefore, oceanic crusts recycled to deep earth will be depleted in nitrogen compared to the newly formed crust at spreading centers. As a result of the long-term mantle convection, large proportions of the bulk silicate earth may have suffered nitrogen extraction via subduction, and this may account for the nitrogen enrichment in the Earth’s atmosphere.

Constraining the volatile budget of the lunar interior has important ramifications for models of Moon formation. While many early and previous measurements of samples acquired from the Luna and Apollo missions suggested the lunar interior is depleted in highly volatile elements like H, a number of high-precision analytical studies over the past decade have argued that it may be more enriched in water than previously thought. Here, we integrate recent remotely sensed near-infrared reflectance measurements of several Dark-Mantle-Deposits (DMDs), interpreted to represent pyroclastic deposits, and physics-based eruption models to better constrain the pre-eruptive water content of lunar volcanic glasses. We model the trajectory and water loss of pyroclasts from eruption to deposition, coupling eruption dynamics with a volatile diffusion model for each pyroclast. Modeled pyroclast sizes and final water contents are then used to predict spectral reflectance properties for comparison with the observed orbital near-infrared data. We develop an inversion scheme based on the Markov-Chain Monte-Carlo (MCMC) method to retrieve constraints between governing parameters such as the initial volatile content of the melt and the pyroclast size distribution (which influences the remotely measured water absorption strengths). The MCMC inversion allows us to estimate the primordial (pre-eruption) water content for different DMDs and test whether their source is volatile-rich. Our results suggest that the parts of the lunar interior sampled by the source material of the DMDs investigated in this study range in water content from 400 to 800 ppm.

A vital factor influencing shale oil exploration in lacustrine shale reservoirs is oil mobility, which is closely associated with the shale pore structure and fluid properties, especially for the low-maturity lacustrine shale in China. In this study, the oil mobility and shale oil potential in the Middle Eocene Shahejie Formation lacustrine shale (MES shale) of the Nanpu Sag in the Bohai Bay Basin were evaluated by using nuclear magnetic resonance (NMR) experiments. The low-maturity MES shale has low porosity with various pore types including intergranular and dissolution pores and microcracks. Its pore space spans nano- to microscale with dominant mesopores. The portion promoting fluid flow is complex and has good self-similarity with high high fractal dimensions. The porosity is related to the thermal maturity, and a higher maturity facilitates pore space development. The oil saturation in low-maturity shale is lesser with low free hydrocarbon due to the low the maturity. Considering the high viscosity and the dead oil, the NMR relaxation mechanism in smaller pore space of low-maturity shale is proposed to bulk relaxation. The movable oil with a viscosity lower than 10 cp accounts consideble pore space in the MES shale. Its viscosity relates with TOC content and thermal maturity. Comparing with other shale oil producing areas, MES shale has similar geological conditions and good brittleness, which hints a suitable and promising shale oil potential at low tectonic position in the Nanpu Sag under the technologies of in situ conversion process and hydraulic fracturing.

Atmospheric isotopologues of water vapor (e.g., HDO) are important tracers for understanding Earth’s hydrological cycles. Most remote sensing measurements of these isotopologues, however, are column averaged values and sparse in space and time. Measurements targeting the planetary boundary layer (PBL) are much rarer. In this study, we retrieved HDO and H from CLARS-FTS observations (2011-2019). The isotopological abundance δD, which represents the relative difference of the HDO/H2O ratio to a standard abundance ratio, is also calculated. The averaged δD retrievals are (−156.1±60.0)‰ with an uncertainty of (6.1±10.2)‰ for LA Basin Survey m and (−344.7±95.0)‰ with an uncertainty of (42.4±31.6)‰ for Spectralon Viewing Observation mode. In LA, the δD shows a seasonal cycle that is primarily driven by the change of atmospheric humidity. The temporal variabilities in δD data between CLARS-FTS and a collocated Total Carbon Column Observing Network (TCCON) observatory are highly correlated. The difference between CLARS and TCCON δD retrievals can primarily be attributed to the difference in their observation geometries. We conclude that the HDO and δD measurements from CLARS-FTS provide high spatial and temporal resolution datasets for further study of hydrological processes in the LA megacity.

The isotopic composition of organic sulfur (δ34Sorg) is a potential recorder of past biogeochemical conditions that has, thus far, received relatively little attention in comparison to the pyrite sulfur isotope record (δ34Spyr). This study presents continuous organic and pyrite δ34S records from three basins of the organic-rich Miocene Monterey Formation, deposited over a similar time interval of c.14.5-6 Ma but under varying depositional conditions. In the San Joaquin basin, δ34Sorg and δ34Spyr average 0‰ and -4‰ respectively and maintain a relatively constant pyrite-organic sulfur isotopic offset of c. 5‰. The Santa Maria Basin exhibits δ34Sorg values that are >10‰ higher than in coeval San Joaquin basin intervals, with average δ34Sorg of c. 24‰ in the upper siliceous member the highest yet reported for marine organic sulfur and roughly 2-3‰ higher than Miocene seawater sulfate. δ34Spyr is consistently c. 12‰ depleted in comparison to organic sulfur in the lower phosphatic member of the Santa Maria Basin, but an abrupt enrichment in both δ34Spyr and δ34Sorg coincident with a sharp lithostratigraphic transition at c. 11 Ma reduces this offset to <4‰ for much of the upper siliceous shales. The Santa Barbara Basin shows a sulfur isotope record intermediate between the San Joaquin and Santa Maria Basins, with average δ34Spyr and δ34Sorg of 3‰ and 12‰ respectively, and relatively consistent c. 10‰ pyrite-organic isotope offset. Records for all three basins demonstrate a close correlation between coeval δ34Spyr and δ34Sorg values which we attribute to derivation from an equivalent, or at least similar, source of sedimentary or water column sulfide. However, marked offset in the isotopic composition of coexisting pyrite and organic sulfur, of variable magnitude within and between basins, implies some contrast in the diagenetic processes underlying sulfur incorporation into the two phases. We argue that the prominent δ34Spyr and δ34Sorg isotopic differences between broadly coeval basin sections are largely the result of differences in sedimentation regime and the associated balance of iron and sulfide supply during diagenesis. A likely factor of additional importance to this iron-sulfide balance is basin-specific sedimentary and water column redox. These findings illustrate the importance of determining independent constraints on the nature of a sedimentary system before conclusions are made relating the sulfur isotope composition of sedimentary species to paleoenvironmental conditions. Additionally, we suggest that records of δ34Spyr have a strong dependence on interaction with organic sulfur during formation, and thus that existing δ34Spyr records are more effectively interpreted in combination with δ34Sorg records.

Venus is the most Earth-like of the terrestrial planets, though very little is known about its surface composition. Thanks to recent advances in laboratory spectroscopy and spectral analysis techniques, this is about to change. Although the atmosphere prohibits observations of the surface with traditional imaging techniques over much of the EM spectral range, five transparent windows between ~0.86 µm and ~1.18 µm occur in the atmosphere’s CO2 spectrum. New high temperature laboratory spectra from the Planetary Spectroscopy Laboratory at DLR show that spectra in these windows are highly diagnostic for surface mineralogy [1]. The Venus Emissivity Mapper (VEM) [2] builds on these recent advances VEM is the first flight instrument specially designed to focus solely on mapping Venus’ surface using the windows around 1 µm. Operating in situ from Venus orbit, VEM will provide a global map of composition as well as redox state of the surface, enabling a comprehensive picture of surface-atmosphere interaction on Venus. VEM will return a complex data set containing surface, atmospheric, cloud, and scattering information. Total planned data volume for a typical mission scenario exceeds 1TB. Classical analysis techniques have been successfully used for VIRTIS on Venus Express [3-5] and could be employed with the VEM data. However, application of machine learning approaches to this rich dataset is vastly more efficient, as has already been confirmed with laboratory data. Binary classifiers [6] demonstrate that at current best estimate errors, basalt spectra are confidently discriminated from basaltic andesites, andesites, and rhyolite/granite. Applying the approach of self-organizing maps to the increasingly large set of laboratory measurements allows searching for additional mineralogical indicators, especially including their temperature dependence. [1] Dyar M. D. et al. 2017 LPS XLVIII, #1512. [2] Helbert, J. et al. 2016. San Diego, CA, SPIE. [3] Smrekar, S.E., et al. Science, 2010 328(5978), 605-8. [4] Helbert, J., et al., GRL, 2008 35(11). [5] Mueller, N., et al., JGR, 2008 113. [6] Dyar M. D. et al. 2017 LPS XLVIII, #3014.

Lacustrine, riverine, and spring carbonates are archives of terrestrial climate change and are extensively used to study paleoenvironments. Clumped isotope thermometry has been applied to freshwater carbonates to reconstruct temperatures, however, limited work has been done to evaluate comparative relationships between clumped isotopes and temperature in different types of modern freshwater carbonates. Therefore, in this study, we assemble an extensive calibration dataset with 135 samples of modern lacustrine, fluvial, and spring carbonates from 96 sites and constrain the relationship between independent observations of water temperature and the clumped isotopic composition of carbonates (denoted by Δ47). We restandardize and synthesize published data and report 159 new measurements of 25 samples. We derive a composite freshwater calibration and also evaluate differences in the Δ47-temperature dependence for different types of materials to examine whether material-specific calibrations may be justified. When material type is considered, there is a convergence of slopes between biological carbonates (freshwater gastropods and bivalves), micrite, biologically-mediated carbonates (microbialites and tufas), travertines, and other recently published syntheses, but statistically significant differences in intercepts between some materials, possibly due to seasonal biases, kinetic isotope effects, and/or varying degrees of biological influence. Δ47-based reconstructions of water δ18O generally yield values within 2‰ of measured water δ18O when using a material-specific calibration. We explore the implications of applying these new calibrations in reconstructing temperature in three case studies.

Since the advent of particle-track methods, it has been understood that the energy loss rate of an ion changes continuously along the particle trajectory, and that energy loss rate in turn affects etching rate. As fission particles slow down and stop, their energy loss rate also drops, which in turn reduces their along-track etching velocity. Conversely, the conceptual model that underlies the way we interpret track length data is based on a more simplified paradigm of a constant along-track etching velocity, vT, with the track tip marking the transition to bulk crystal etching, vB, at its maximum etchable extent. We present a new model for the etching and revelation of confined fission tracks that incorporates and attempts to quantify variable along-track etching velocity, vT(x). The model attempts to fully represent the track-in-track (TINT) revelation process, consisting of etchant penetration along semi-tracks intersecting the polished grain surface, expansion of etchant channels to intersect latent confined tracks, etching of confined tracks, and finally selection by the analyst of tracks suitable for measurement. We successfully use the model to fit step-etching data for spontaneous and unannealed and annealed induced confined tracks in Durango apatite. All model fits support a continuous decrease in etching velocity toward track tips, and lead to a series of insights concerning the theory and practice of fission-track thermochronology. Etching rates for annealed induced tracks in Durango apatite are much faster than those for unannealed induced and spontaneous tracks, impacting the relative efficiency of both confined track length and density measurements, and suggesting that high-temperature laboratory annealing may induce a transformation in track cores that does not occur at geological conditions of partial annealing. However, we are still investigating to what degree that pattern holds for other apatite varieties. The model also quantifies how variation in track selection criteria by analysts, which we approximate as the ratio of along-track to bulk etching velocity at the etched track tip (vT/vB), is likely to play a first-order role in the reproducibility of confined length measurements, and may explain the bulk of the variability observed in inter-laboratory calibration exercises. The concept of a “fully etched track” is subjective. Finally, the model illustrates how a substantial proportion of tracks that are intersected are not measured, which in turn indicates that length biasing is likely to be an insufficient mathematical basis for predicting the relative probability of detection of different track populations.