Geochemistry

The purpose of this study was to examine the carbazole as an indicate of the petroleum expulsion-implications on petroleum migration.Taiwan lies about 150 kilometers off the Fukian coast of the China mainland. It is separated from the latter by the Taiwan Strait which has an average depth of 100 meters. The main island of Taiwan is spindle-shaped, with the longitudinal axis extending roughly north-south for a length of 385 kilometers. The maximum width is 143 kilometers. The Central Range forms the backbone ridge and is the main water divide between the eastern and the western slopes of Taiwan. It bisects Taiwan island into two unequal parts, the western flank being about twice as wide as the eastern flank. Taiwan can be broadly divided into three major geologic provinces: the Central Range, the western foothills and the Coastal Range in eastern Taiwan. Northwestern Taiwan is the major petroleum province of Taiwan and is believed to contain several trillion cubic feet of gases in place as well as substantial amounts of oils and condensates. Extensive exploration activities have been carried out in this region, with a number of fields being discovered and put into production.

Granulites are relatively rare but provide us a natural window into the composition, structure and P-T conditions of the lower crust and process of continental growth. Therefore, the correct determination of the P-T conditions of exposed granulites is extremely important. UHT metamorphic conditions are best preserved and most commonly reported from the relatively rare Mg-Al rich metapelitic granulites as they preserve characteristic mineral assemblages like sapphirine + quartz, spinel + quartz, orthopyroxene + sillimanite etc., indicating HT-UHT metamorphism. Likewise, in the the Eastern Madurai domain of South India, the rare Mg-Al rich metapelitic granulites preserve characteristic mineral assemblages and record peak metamorphic temperatures of ≈1000oC at 6 Kbar [1]. However, the co-metamorphosed mafic granulites from the region, comprising garnet + clinopyroxene + orthopyroxene ± quartz, record peak temperatures of ≈800-850oC at 7-8 Kbar, obtained from Fe-Mg exchange thermometers...

The process responsible for the genesis and the initial morphological evolution of shearband boudins is controlled by the buckling laws. In this model, the generation of boudins begins with folding of tabular competent veins of different thickness immersed in a less competent matrix. Veins thicker than a given critical value form initial asymmetric open folds that evolve by asymmetric antithetical rotation and later by an internal mass redistribution with translation along the interface vein-matrix. On the other side, the veins thinner than the critical value follow the folding process until it culminates with the coalescence and stacking of the folds. By this mechanism the critical thickness is reached and these bodies are prone to suffer a new phase of boudinage similar to that followed by the originally thicker veins. Therefore, all deformed tabular veins, embedded in a ductile matrix, converge to classical shearband boudin morphology, independently from their original thickness.

The difficulties in the identification of boudinated bodies happen whenever isolated or isolated look-like boudins structures occur. Figure shows the criteria for identifying micro and meso structures that could be misunderstand with boudins.

The boudins are generally finite objects of easy identification in the field. They are excellent structures for learning the measurement of linear and planar structures. Geometric and morphological parameters of the boudins allow drawing conclusions about several structural parameters, such as, kinematics. vorticity, strain rate and shear strain.

La genesis y evolucion morfologica inicial de los "boudins� de tipo �shearband" estan controlados por mecanismos de plegamiento. En este modelo, el "boudinage" comienza con el plegamiento de cuerpos tabulares (venas) de diferentes espesores, inmersos en una matriz menos competente. Las venas mas gruesas exceden un espesor critico que determina la formacion inicial de un pliegue abierto. Posteriormente evoluciona por rotacion antitetica en relacion con la cinematica de la zona de cizalla y por traslacion de masa a lo largo de la interfase vena-matriz, conduciendo a la morfologia clasica de un "shearband boudin�. Por su parte, los cuerpos comparativamente mas delgados continuan plegandose hasta que se produce la union y apilamiento de los flancos de los pliegues (�stacked-folds�).Mediante este proceso se alcanza el espesor critico necesario para que se desarrolle una nueva fase de "boudinage" similar a la seguida por las venas gruesas

The internal structure of a shearband boudin result ing from an original igneous, hydrothermal or metamorphic segregation tabular rigid body is a sub ject of scientific interest. It allows understandin g the deformation mechanisms acting on homogeneous quartz aggregate activated during simple shear progressive deformation. This work is focused on the characterization of the int rnal evolution of shearband boudins, using microtextural analysis, fluid inclusions studies, f ractal and OCP analysis. The proposed interpretativ model shows the several structural stages that can be well established during the process of the inter nal evolution of shearband boudin. In the first stage a quartz-rich layered body was s ubmitted to the boudinage process. This layer has most likely a segregation or igneous and hydrotherm al texture, in equilibrium with Lcw or Lwc fluids, catched in isolated fluid inclusions (FI). The quar tz fabric is supposed to be random or controlled by a nucleation/growth pr...

Quartz microstructure analysis based on classical optical microscopy, is appointing to the identification of features related with dominial quartz studies. Microstructural features defined in this study include the concepts of microstructures, microstructural elements, microstructural features, fabric elements, elementary textures, textural elements and textural features (e.g., Vernon, 1976 and Kosaka, 1980). Petrographic analysis was focused on the identification of quartz microstructures, such as intra-granular microstructures, inter-granular boundary, and their relation to the deformation mechanisms activated during a simple shear progressive deformation event. These structures were quantified following the methodology developed by Kosaka (1980). To ensure a random sampling, measurement points were picked from a standard grid that covers the total thin section area. A statistically significant number of points were analysed. Three geometrical tools were used to apply the quantification to each textural domain: point counting, the line intersection method and window counting. Point counting was used to select grains, line intersections to quantify linear microstructures, and window counting to quantify microstructures based on spatial relationships between grains or within a selected grain. Each microstructural feature was determined in relation to the measured grain size. The low birefringence was controlled to avoid biases, such as the nonuse of perpendicular sections to the optical axis. The classification after Kosaka et al. (1999) was used to determine quartz internal deformation stages, and three main grain types of quartz were identified. Less deformed quartz shows simple patterns of undulose extinction, more complex based jigsaw ones, or chess-board and banded geometries. The second type includes quartz grains with large subgrains. Most deformed quartz grains include clusters of grains differentiated by their granular dimensions. In order to quantify boundary mobility, four textural states representing incremental degrees were defined: i) local bulging, ii) proto-subgrain rotation, iii) boundary grain migration and iv) jigsaw boundary geometry. This methodology was applied on the petrographic study of internal shearband boudin microstructures related with a Variscan HT simple shear zone.

The work is focused on the P-T path recorded on internal shearband boudin microstructures, developed during simple shear progressive deformation (Malpica-Lamego Ductile Shear Zone – MLDSZ, NW Portugal). In the studied area, MLDSZ is a NW-SE striking Variscan crustal shear zone with a subvertical and west-dipping foliation and a sub-horizontal stretching lineation; it is recorded as a heterogeneous simple shear zone with bulk left-lateral kinematics (Pamplona and Rodrigues, 2011). The deformation zone is marked by a generalized foliation (Sn) defined by Bt+Ms±Sil and a stretching mineral lineation marked by sillimanite fibres. Microstructural analysis, fluid inclusions studies, Raman spectroscopy, crystallographic preferred orientation on quartz grains and fractal geometry based analysis were applied to the boudins (Rodrigues et al., submitted). In several microstructural domains, the sharp-tip domain, formed by recrystallized coarse quartz grains, and internal secondary shear zones ...

Mineral distribution pattern of Variscan post-tectonic granites from Vila Pouca de Aguiar Pluton (NE Portugal) were analysed with methods partially based on fractal geometry and, with respect to rock inhomogeneity and anisotropy. The result of the analysis provides information about magmatic flux and mineral equilibrium processes in a crystallizing magma chamber. In addition, the used methods may also provide important information for the ornamental rock industry, because they allow fast and automatic evaluation of economic rock parameters.

The ancient Maya community of Lamanai, Belize, is well known for its span of occupation from the Early Preclassic (before 1630 BC) to the present. Although most centers in the central and southern Maya Lowlands were abandoned during the Terminal Classic period (AD 750–1000), ceramic and stratigraphic evidence at Lamanai has shown continuous occupation from the start of the Early Preclassic to the Spanish Conquest. In this paper, we present the first complete set of radiocarbon dates from this important site, including 19 new accelerator mass spectrometry (AMS)14C dates. We use these dates to build Bayesian models for a Terminal Classic structure and an Early Postclassic structure in the site center. This method assists in the refinement of older, conventional dates and provides key chronological information about the site during this volatile time. Adjustments to the standard, uniform distribution model are made using exponential, long-tail, and trapezoidal distributions to incorpor...

Hot springs can occur in amagmatic settings, but the mechanisms of heating are often obscure. We have investigated the origin of the Truth or Consequences, New Mexico low-temperature (approximately 41°C) hot springs in the southern Rio Grande Rift. We tested two hypotheses that could account for this amagmatic geothermal anomaly: lateral forced convection in a gently dipping carbonate aquifer and circulation through high-permeability crystalline basement rocks to depths of 8 km that is then focused through an overlying faulted hydrologic window. These hypotheses were tested using a regional two-dimensional hydrothermal model. Model parameters were constrained by calibrating to measured temperatures, specific discharge rates, and groundwater residence times. We collected 16 temperature profiles, 11 geochemistry samples, and 6 carbon-14 samples within the study area. The geothermal waters are Na + /Cl À -dominated and have apparent groundwater ages ranging from 5500 to 11 500 years. Hot-spring geochemistry is consistent with water/rock interaction in a silicate geothermal reservoir, rather than a carbonate system. Peclet number analysis of temperature profiles suggests that specific discharge rates beneath Truth or Consequences range from 2 to 4 m year À1 . Geothermometry indicates maximum reservoir temperatures are around 170°C. Observed measurements were reasonably reproduced using the deep circulation permeable-basement modeling scenario (10 À12 m 2 ) but not the lateral forced-convection carbonate-aquifer scenario. Focused geothermal discharge is the result of localized faulting, which has created a hydrologic window through a regional confining unit. In tectonically active areas, such as the Rio Grande Rift, deep groundwater circulation within fractured crystalline basement may play a more prominent role in the formation of geothermal systems than has generally been acknowledged.

O Platô de São Joaquim (PSJ) situa-se no Planalto Sul de Santa Catarina, no extremo sudeste do Planalto Meridional do Brasil. O platô sobrepõe-se aos basaltos da Formação Serra Geral, os quais são dispostos principalmente na forma de derrames pahoehoe, mas também de derrames a'a'. As rochas félsicas do Platô de São Joaquim configuram extensos derrames de geometria tabular e espessura de até 100 m que se distribuem por 280 km². Morros testemunhos nas circunvizinhanças conservam porções remanescentes destes derrames, evidência de que sua extensão fora muito maior e que agora se encontra reduzida pela erosão. A estratigrafia da sequência sobreposta aos basaltos comumente arquiteta-se da seguinte forma: (1) nível decamétrico de rochas de caráter transicional, representadas por vulcanitos afaníticos de cor cinza-avermelhada ou vermelha, maciços a amigdaloides podendo conter geodos decimétricos; (2) nível métrico saprolítico amigdaloide de cor amarela e geometria ondulada, com amígdalas estiradas e atualmente preenchidas por argilas brancas, brechas autoclásticas formadas por púmice/escória intemperizados e lentes de pitchstone; (3) nível basal félsico decamétrico formado por lentes de pitchstone e rochas afaníticas com bandamento de fluxo laminar plano-paralelo, contorcido ou dobrado; (4) nível félsico decamétrico com disjunções em lajes; (5) nível félsico de espessura decamétrica (até 65 m) formado por rochas faneríticas finas maciças, com ou sem disjunções tabulares; (6) na porção superior do nível maciço observam-se raras amígdalas. Devido à falta de evidências que atribuam uma gênese ignimbrítica a estas rochas, tais vulcanitos do platô de São Joaquim são preliminarmente designados como Riolitos de Platô da Formação Serra Geral.

The Valanginian Stage is marked by a period of global positive δ13C carbon cycle perturbation and biotic crises, which are collectively referred to as the Valanginian event (VE). Many attempts have been made to link the Paraná-Etendeka large igneous province volcanism with the VE. However, currently there is no conclusive proof to support this hypothesis, since the timing and duration of the volcanic activity are not known with sufficient precision. In this study, we significantly revise the time scales of magmatism and environmental impact of the Paraná magmatic province (PMP) in Brazil with new high-precision zircon U-Pb ages from the low-Ti Palmas and high-Ti Chapecó sequences. Our data demonstrate that significant volumes of low-Ti silicic rocks from the PMP erupted rapidly at ca. 133.6 Ma within 0.12 ± 0.11 k.y. The age of the high-Ti Chapecó sequence from central PMP is constrained at ca. 132.9 Ma and thus extends the duration of magmatic activity by ∼700 k.y. Our new ages are...

A radiative transfer sky model was used to derive the reduction in UV flux on the surface of Mars due to rocks, pits, cracks, and overhangs. The implications for planetary protection and the survival of simple organic molecules in terms of the extension o

Prelaunch planetary protection protocols on spacecraft are designed to reduce the numbers and diversity of viable bioloads on surfaces in order to mitigate the forward contamination of planetary surfaces. In addition, there is a growing appreciation that prelaunch spacecraft cleaning protocols will be required to reduce the levels of biogenic signature molecules on spacecraft to levels that will not compromise life-detection experiments on landers. The biogenic molecule, adenosine triphosphate (ATP) was tested for long-term stability under simulated Mars surface conditions of high UV flux, low temperature, low pressure, Mars atmosphere, and clear-sky dust loading conditions. Data on UV-induced ATP degradation rates were then extrapolated to a diversity of global conditions using a radiative transfer model for UV on Mars. The UV-induced degradation of ATP tested at 4.1 W m -2 UVC (200-280 nm), -10 • C, 7.1 mb, 95% CO 2 gas composition, and an atmospheric opacity of τ = 0.1 yielded a half-life for ATP of 1342 kJ m -2 ; or extrapolated to approximately 22 sols on equatorial Mars with an atmospheric opacity of τ = 0.5. Temperature was found to moderately affect ATP degradation rates under martian conditions; tests at -80 or 20 • C yielded ATP half-lives of 2594 or 1183 kJ m -2 , respectively. The ATP degradation rates reported here are over 10 orders of magnitude slower than the UV-induced biocidal rates reported in the literature on the inactivation of strongly UV-resistant bacterial spores from Bacillus pumilus A.C.,

The Rudnik orefield is one of the well-known skarn-replacement and high-temperature hydrothermal Pb-Zn-Cu-Ag-Bi-W polymetallic sulfide deposits, and is a part of the Sumadija Metallogenic District, Serbia. It comprises ore bodies grouped into several major ore zones. The pseudostratified and platelike ore bodies have relatively high content of valuable metals. The average content varies in wide ranges: Pb (0.94-5.66 wt%), Zn (0.49-4.49 wt%), Cu (0.08-2.18 wt%), Ag (50-297 ppm), Bi (~100-150 ppm), and Cd (~100-150 ppm). Generally, a complex mineral association has been determined. Iron sulfides, arsenopyrite, chalcopyrite, sphalerite, galena and sulfosalts are abundant minerals in the ore. Carrier minerals of Bi and Ag are Bi-sulfosalts, such as galenobismutite, cosalite, Ag-bearing aschamalmite, vikingite, schirmerite and gustavite. Copper, Ag and Pb-Sb sulfosalts have been found only locally. Complex Ni-minerals (sulfides, arsenides and sulfoarsenid?s) with Fe, Co and Ag were forme...

The results of perennial research of several Serbian zeolitic tuffs enriched with HEU-type minerals are presented in this paper. There are several recognized zeolitic tuff deposits containing HEU-type minerals: Zlatokop, Igros, Beocin, Toponica, Slanci, but their comparative mineralogical and crystallochemical features have not been studied in detail so far. These zeolitic tuff deposits are spatially and genetically connected to volcanic and pyroclastic rocks of marine and lake environments of Senonian and Eocene, and Neogene age, respectively. As a result of devitrification and diagenesis process of volcanic glass within zeolitic tuffs hypocrystalline porphiry and vitroclastic textures occur. The studied zeolitic tuffs are mainly composed of heulandite occuring in a form of needle- to plate-like crystals of 0,1 do 100 ?m in length, associated with other silicates. Depending on the type and content of exchangeable cations as well as the thermal stability of these raw materials, 24 c...

The article deals with theoretical cognitions and empirical findings regarding evacuation, especially human behaviour during it. The authors define evacuation and classify it, which is followed by a description of psychosocial theories dealing with evacuation, especially the »mass panic« view, the affiliation and normative approach and social identity approach. The article also presents the psychological characteristics of an evacuation. The second part of the article is based on the results of a public opinion survey and interviews conducted in October 2012 concerning the preparedness of the population, institutions and companies to evacuate in the event of a nuclear accident at the Kr{ko Nuclear Power Plant (NPP) in Slovenia. The survey covered settlements located within a 3-kilometre radius around the NPP. The interviews were conducted with the managers of 12 major companies and institutions operating in the Municipality of Kr{ko. The survey and interviews confirmed some basic th...

Geochronological research of the Lincang Batholith is one key scientific problem to discuss the tectonic evolution of the Tethys. Two granitic specimens were selected from the Mengku-Douge area in the Lincang Batholith to perform the LA-ICPMS Zircon U-Pb dating based on thorough review of petrological, geochemical, and geochronological data by the former scientists. Rock-forming age data of biotite granite specimen from Kunsai is about 220 Ma, the Norian age. However, the west sample from Mengku shows 230 Ma, the Carnian age. The later intrusion in Kunsai area located east to the Mengku area shows directly their uneven phenomena in both space and time and may indirectly reflect the space difference of the contraction-extension transformation period of the deep seated faults. Considering the former 40Ar/39Ar data and the outcrop in Mengku, the Lincang Batholith should have experienced one tectonic exhumation and regional subsidence cycle. The regional subsidence cycle has close relat...

The people who inhabited the El
Gigante rockshelter had a deep knowledge of
the ecological resources around them and were
constantly experimenting with it in novel ways.
In terms of color technology, they used highquality
hematite fixed with either kaolin or
calcium sulfate to decorate gourds or produce
rock art. The dyeing of textiles demonstrates a
high level of technological manipulation of
plants, regardless of whether they used indigo,
Justicia sp. or another plant. It required the use
of “olla podrida” or “rotten pot” to produce
temporary changes in the molecules of the dyes
to apply them, fix them, and make them
resistant to solar radiation. The fabulous
preservation of El Gigante has opened new
research lines in terms of color technology for
the Honduras and El Salvador region during the
pre-Hispanic period

Cassini results indicate that solar photons dominate energy deposition in Titan's upper atmosphere. These dissociate and ionize nitrogen and methane and drive the subsequent complex organic chemistry. The improved constraints on the atmospheric composition from Cassini measurements demand greater precision in the photochemical modeling. Therefore, in order to quantify the role of solar radiation in the primary chemical production, we have performed detailed calculations for the energy deposition of photons and photoelectrons in the atmosphere of Titan and we validate our results with the Cassini measurements for the electron fluxes and the EUV/FUV emissions. We use high-resolution cross sections for the neutral photodissociation of N 2 , which we present here, and show that they provide a different picture of energy deposition compared to results based on low-resolution cross sections. Furthermore, we introduce a simple model for the energy degradation of photoelectrons based on the local deposition approximation and show that our results are in agreement with detailed calculations including transport, in the altitude region below 1200 km, where the effects of transport are negligible. Our calculated, daytime, electron fluxes are in good agreement with the measured fluxes by the Cassini Plasma Spectrometer (CAPS), and the same holds for the measured FUV emissions by the Ultraviolet Imaging Spectrometer (UVIS). Finally, we present the vertical production profiles of radicals and ions originating from the interaction of photons and electrons with the main components of Titan's atmosphere, along with the column integrated production rates at different solar zenith angles. These can be used as basis for any further photochemical calculations.

This research was conducted in the area Tanjung Buli, East Halmahera regency. This area has iron ore resources in the prospects for exploration to exploitation with data obtained using spaced borehole 25meter. Point kriging method with software SGeMS (Standard Geostatistic Modeling software) used for assessing of iron ore resource with size of block model dimensions 41x23x205 and unit blocks 25x25x1 (in meters). The results of the assessment point kriging method obtained estimated values of Fe and kriging variance value is then used for the classification of resources based on relative kriging standard deviation (RKSD) as classification of resource measured, indicated, and inferred. The results of cross-validation of the assay data-Fe-Fe estimation data from point kriging method. The results of resource assessment Fe of  measured amounted to 3,081,125 tonnes, Indicated amounted to 6,878,563 tonnes and Inferred amounted to 97,781,563 tonnes. The pattern of spread showed high Fe conte...

Methane (CH4) emissions induced by Large Igneous Provinces have the potential to contribute to global environmental changes that triggered mass extinctions in Earth’s history. Here, we explore the source of methane in gas samples from central Sichuan Basin, which is within the Emeishan Large Igneous Province (ELIP). We report evidence of high methane formation temperatures (between 249−17/+19 and 256−20/+22 °C) from clumped methane measurements and mantle-derived signatures of noble gases, which verify that oil-cracked CH4 and pyrobitumen are by-products within the reservoirs, associated with hydrothermal activity and enhanced heating by the ELIP. We estimate the volume of oil-cracked CH4 induced by the ELIP and argue that CH4 emissions would have been sufficient to initiate global warming prior to the end of the Permian. We also suggest that similar emissions from oil-cracked CH4 associated with the Siberian Traps Large Igneous Province may also have contributed to the end-Permian ...

For exploring the distribution of oil slick related to gas hydrate or petroleum in the northern part of South China Sea and evaluating the potential of ENVI/ASAR radar data for detecting oil slick, this paper tries to detect the oil slick on ocean surface of some potential areas in South China Sea and map oil slick from anomaly area in radar image. Seven surface oil slicks in Qiongdongnan Basin and four potential targets of oil slicks in Taixi-Dongsha Basin were detected and extracted by using ENIV/ASAR data. The anomalies of the radar image representing oil slick are validated by in-site sampling and laboratory analyzing. The Gas Chromatograph (GC) results of the extracted oil from the water samples gathered from the sites of detected oil slick demonstrate a typical composition of oil rather than that of ocean microbial origins, and Total Organic Carbon (TOC) concentrations in two designed vertical profiles keep steady in different depths, showing that the organic contents in water column are steady from the deep area to ocean surface. These results suggest the detected oil slick is a thin floating oil rather than a thick spill. Influencing factors to the results of oil slick detection including wind speed, current, small islands and capes as well as deep-sea petroleum reservoirs are discussed. The results in this study exhibit that extracting the anomaly signals related to oil slick related to oil/gas seeps using image processing techniques from ENVI/ASAR data is helpful to predict anomaly areas as potential targets for further exploration in this area.

The origin of hypogene alteration and mineralization features in the Escondida porphyry Cu deposit resulted from intense overprinting related to three main hydrothermal stages. The beginning of each stage is recorded by deposition of bright quartz crystals on vein walls that precipitated from high-temperature fluids. In the deepest zones of the deposit, the earliest stage started with exsolution of intermediate-density fluids, which transported high concentrations of Cu, whereas Mo was not detected. However, in the shallow zones, the early stage began with depressurization and unmixing of intermediatedensity fluids, which generated both a hypersaline and vapour-rich fluid phase, producing an important geochemical segregation between both phases. The transitional stage also started with circulation of intermediate-density fluids but never experienced unmixing. These fluids transported the highest Mo concentrations in the deposit; however, Cu displays lower concentrations relative to intermediate-density fluids from the early stage. The beginning of the late stage was also associated with intermediate-density fluids; however, Cu and Mo were below the detection limits in most of the analysed fluids. During the evolution of the three stages, the fluids experienced gradual cooling, which promoted the precipitation of euhedral and zoned quartz crystals that overgrew the early highluminescence quartz generations. Sometimes, sulfide minerals display euhedral crystal boundaries with zoned quartz, suggesting that mineralization started during these phases. The latest events detected in each main stage are linked to cooler and low-salinity fluids, from which dark quartz and hypogene sulfides precipitated along microfractures and interstitial spaces developed in the earlier quartz generations.

Stream discharge-concentration relationships are indicators of terrestrial ecosystem function. Throughout the Amazon and Cerrado regions of Brazil rapid changes in land use and land cover may be altering these hydrochemical relationships. The current analysis focuses on factors controlling the discharge-calcium (Ca) concentration relationship since previous research in these regions has demonstrated both positive and negative slopes in linear log 10 dischargelog 10 Ca concentration regressions. The objective of the current study was to evaluate factors controlling stream discharge-Ca concentration relationships including year, season, stream order, vegetation cover, land use, and soil classification. It was hypothesized that land use and soil class are the most critical attributes controlling discharge-Ca concentration relationships. A multilevel, linear regression approach was utilized with data from 28 streams throughout Brazil. These streams come from three distinct regions and varied broadly in watershed size (<1 to >10 6 ha) and discharge (10 -5.7 to 10 3.2 m 3 sec -1 ). Linear regressions of log 10 Ca versus log 10 discharge in 13 streams have a preponderance of negative slopes with only two streams having significant positive slopes. An ANOVA decomposition suggests the effect of discharge on Ca concentration is large but variable. Vegetation cover, which incorporates aspects of land use, explains the largest proportion of the variance in the effect of discharge on Ca followed by season and year. In contrast, stream order, land use, and soil class explain most of the variation in stream Ca concentration. In the current data set, soil class, which is related to lithology, has an important effect on Ca concentration but land use, likely through its effect on runoff concentration and hydrology, has a greater effect on discharge-concentration relationships.

The formation of Paraiba do Sul river delta plain in the coast of Rio de Janeiro state, Brazil, gave rise to diverse lagoons formed under different sea level regimes and climate variations. Sedimentary core lithology, organic matter geochemistry, and isotopic composition (δ 13 C and δ 15 N) were analyzed to interpret the sedimentation of the paleoenvironment of the Lagoa Salgada carbonate system. Different lithofacies reflect variations of the depositional 15 environment. The abundance of silt and clay between 5.8 to 3.7 ka B.P., enhances the interpretation of a transgressive system, which promoted the stagnation of coarse sediment deposition due to coast drowning. Geochemistry data from this period (5.8-3.7 ka B.P.) suggest the dominance of a wet climate, with an increase of C3 plant and a marked dry event between 4.2-3.8 ka B.P. This dryer event also matches with previous published records from around the world, indicating a global event at 4.2 ka B.P. Between 3.8-1.5 ka B.P., Lagoa Salgada was isolated, sand and silt arrived at the system by 20 erosion with the retreat of the ocean and less fluvial drainage. Geochemistry from this moment marks the changes to favorable conditions for microorganisms active in the precipitation of carbonates, forming microbial mats and stromatolites in the drier phase. Severe and prolonged drought around the world characterize the 4.2 ka BP climatic event, and is reflected in proxy records 25

Negative stable carbon isotopic excursions have been observed throughout most of the mid‐depth (~1000–3000 m) Atlantic Ocean during Heinrich Stadial 1 (HS1) and the Younger Dryas (YD). Although there is an agreement that these mid‐depth excursions were in some way associated with a slowdown of the Atlantic Meridional Overturning Circulation (AMOC), there is still no consensus on the precise mechanism(s). Here we present benthic stable carbon and oxygen isotopic (δ13C and δ18O) records from five cores from the western equatorial Atlantic (WEA). Together with published benthic isotopic records from nearby cores, we produced a WEA depth transect (~800–2500 m). We compare HS1 and YD data from this transect with data from previously published North and South Atlantic cores and demonstrate that the largest negative δ13C excursions occurred in the WEA during these times. Moreover, our benthic δ18O records require the presence of two water masses flowing from the Southern Ocean, bisected by...

The health of the coral ecosystem at Abrolhos was evaluated using foraminifers and geochemistry. A total of 54 bottom sediment samples was collected for foraminifers, and 18 samples were collected for geochemistry by scuba divers at nine stations from different depth domains (A: 1 m b depth ≤ 10 m; B: 10 m b depth ≤ 15 m, and C: 15 b depth ≤ 25 m) in January and July 2005. Transparency, water temperature, salinity, and dissolved oxygen were measured in situ near the sea bed. The sediment was analyzed for total organic carbon and nitrogen, carbonate content, phosphorus, mineralogy, and grain size. Foraminifers were identified to 136 genera and sorted into functional groups for FORAM index (FI). Calcite and aragonite predominated, and organic matter of marine origin was found in the sediment. Hydrodynamic processes, organic matter, and temperature seemed to control the foraminifer distribution in austral summer, whereas salinity coupled with CaCO 3 content and grain size was most important in austral winter. At most stations, the FI indicated that the environment was suitable for coral reef growth, but it needs to be applied with caution in Brazilian waters. The use of foraminifer taxocenosis, the FI, Amphistegina spp. taphonomy, and geochemistry showed good resolution for measuring environmental quality and could be used in coral reef monitoring programs of the Southwestern Atlantic.

This article surveys ongoing research of the Legibility Enhancement of Ostraca (LEO) team of Tel Aviv University in the field of computerized paleography of Hebrew Iron Age ink-written ostraca. We perform paleographic tasks using tools from the fields of image processing and machine learning. Several new techniques serving this aim, as well as an adaptation of existing ones, are described herein. This includes testing a range of signal-acquisition methodologies, out of which multispectral imaging and Raman spectroscopy have matured into imaging systems. In addition, we deal with semior fully automated facsimile construction and refinement, facsimile, and character evaluation, as well as the reconstruction of broken character strokes. We conclude with future research directions, addressing some of the long-standing epigraphic questions, such as the number of scribes in specific corpora or detection of chronological concurrences and inconsistencies.

We examine how multispectral imaging can be used to document and improve reading of ancient inscriptions. The research focuses on ostraca, texts written in ink on ceramic potsherds. Three corpora of Hebrew ostraca dating to the Iron Age II were imaged in visible and near infrared light using a state-of-the-art commercial spectral imager. To assess the quality of images, we used a new quality evaluation measure which takes into account various contrast and brightness transformations. We show that there exists a wavelength range where the readability of ostraca is enhanced. Moreover, we show that it is sufficient to use certain bandpass filters to achieve the most favorable image. Our study paves the way towards a low cost multispectral method of imaging ostraca inscriptions.

We present a source-to-sink environmental magnetic study of a sediment core from Lake Sanabria (NW Iberian Peninsula) and rocks of its catchment. Our results indicate the occurrence of magnetite, and likely also pyrrhotite, in sediments accumulated between ca 26 and 13 cal ka BP in a proglacial lake environment. These minerals appear to dominate also the magnetic assemblage of Paleozoic rocks from the lake catchment. This indicates that sedimentation was then driven by the erosion of glacial flour, which suffered minimal chemical transformation due to a rapid and short routing to the lake. A sharp change in magnetic properties observed in the lake sediments between 13 and 12.6 cal ka BP reflects the rapid retreat of glaciers from the lake catchment. Sediments from the upper half of the studied sequence, accumulated after 12.6 cal ka BP in a lacustrine environment with strong fluvial influence, contain magnetite and smaller amounts of maghemite and greigite. We interpret that greigite grew authigenically under anoxic conditions caused by enhanced accumulation of organic matter into the lake. The occurrence of maghemite in these sediments suggests pedogenic activity in the then deglaciated lake catchment prior to the erosion and transportation of detrital material into the lake.

Central Chile is heavily exploited for mineral and water resources, with agriculture and large urban populations all creating intensive landscape use. Few records of past environmental and climate change are available that afford a broader context. To aid in this assessment, we present a 700-year reconstruction from Laguna del Maule (LdM) in the high Andes of central Chile based on sedimentological, geochemical, diatom and pollen analyses. The age model is based on 210Pb/137Cs and 14C dating tied into known volcanic eruptions. Sedimentology consists of organic-rich sediments and diatom oozes with several interspersed volcanic-rich facies and two tephra deposits. Sediment geochemistry exhibits increased productivity (high Br/Ti, biosilica) and more dominant oxic conditions (high Fe/Mn) from AD 1300 to 1400 and from AD 1650 to 1850, likely during periods of relatively lower lake levels and better development of littoral environments. However, during this later period, high elevation v...

The multi-proxy analysis of sediment cores recovered in karstic Lake Estanya (42°02' N, 0°32' E; 670 m a. s. l., NE Spain), located in the transitional area between the humid Pyrenees and the semi-arid Central Ebro Basin, provides the first high-resolution, continuous sedimentary record in the region, extending back the last 21 000 years. The integration of sedimentary facies, elemental and isotopical geochemistry and biogenic silica, together with a robust age model based on 17 AMS radiocarbon dates, enables precise reconstruction of the main hydrological and environmental changes in the region during the last deglaciation. Arid conditions, represented by shallow lake levels, predominantly saline waters and reduced organic productivity occurred throughout the Last Glacial Maximum (21 -18 cal kyrs BP) and the late glacial, reaching their maximum intensity during the period 18 -14.5 cal kyrs BP (including Heinrich event 1) and the Younger Dryas (12.9 -11.6 cal kyrs BP). Less saline conditions characterized the 14.5 -12.6 cal kyrs BP period, suggesting higher effective moisture during the Bölling/Allerød. The onset of more humid conditions started at 9.4 cal kyrs, indicating a delayed hydrological response to the onset of the Holocene which is also documented in several sites of the Mediterranean Basin. Higher, although fluctuating, Holocene lake levels were punctuated by a mid Holocene arid period between 4.8 and 4.0 cal kyrs BP. A major lake-level rise occurred at 1.2 cal kyrs BP, conducive to the establishment of conditions similar to the present and interrupted by a last major water level drop, occurring around 800 cal yrs BP, which coincides with the Medieval Climate Anomaly. The main hydrological stages in Lake Estanya are in phase with most Western Mediterranean and North Atlantic continental and marine records, but our results also show similarities with other Iberian and northern African reconstructions, emphasizing peculiarities of palaeohydrological evolution of the Iberian Peninsula during the last deglaciation.