Miracle-dz/UniFAR-FTUs huggingface dataset:
Reproducing hydrogeochemical conditions triggering the formation of carbonate and phyllosilicate alteration mineral assemblages on Mars (Nili Fossae region)

[1] The cooccurrence of Mg-Fe-Ca carbonate and stratigraphically lower, phyllosilicate-bearing rock units, identified in the Nili Fossae region on Mars, may reveal a CO2-driven aqueous alteration process on ancient Mars. We reproduce hydrogeochemical conditions for concurrent carbonate and phyllosilicate formation in rock columns by using hydrogeochemical one-dimensional transport modeling, which is based on chemical equilibrium thermodynamics. Our models assume the isochemical, low-temperature equilibration of ultramafic rocks with pure water at varying atmospheric CO2 partial pressure, water-to-rock ratio, temperature, and rock composition. Equilibration among (1) mineral assemblages of olivine-rich rocks (18–28 wt% MgO), (2) pure water (water-to-rock ratio: 500–50 mol mol−1), (3) CO2 transferred from the atmosphere (CO2 partial pressure lower than ∼2 bars and higher than ∼0.01 bar) at ∼278 K, and (4) 100,000 years of diffusive mass transport create hydrogeochemical conditions enabling the concurrent formation of Mg-rich Mg-Fe-Ca solid-solution carbonate and stratigraphically lower phyllosilicate-rich alteration assemblages in rock columns. The modeled composition of alteration mineral assemblages, their depth distribution, and carbonate composition are similar to the observations from the Nili Fossae region. Higher equilibration temperature (373 K) results in the formation of Ca-dominated Ca-Mg carbonate instead of Mg-rich Mg-Fe-Ca carbonate and in an inverse stratification with phyllosilicate-rich units overlying carbonate-rich units. Modeling results suggest that rocks in the Nili Fossae region, hosting the carbonate and phyllosilicate mineral assemblage, have been exposed to a groundwater alteration process driven by atmospheric CO2 partial pressures ranging between ∼2 bars and ∼0.01 bar at low temperature (∼278 K).
Chemical and dynamical response to the 11‐year variability of the solar irradiance simulated with a chemistry‐climate model

Atmospheric effects of the solar irradiance variations during 11‐year solar cycle are investigated using a chemistry‐climate model. The model is enhanced by a more detailed parameterization of the oxygen and ozone UV heating rates. The simulated ozone response to the imposed solar forcing shows a positive correlation in the tropical stratosphere and a negative correlation in the tropical mesosphere, in agreement with theoretical expectation. The model suggests an acceleration of the polar night jets in both hemispheres and a dipole structure in the temperature changes at high latitudes. The model results also show an alteration of the tropospheric circulation air resulting in a statistically significant warming of 1 K in the annual mean surface air temperature over North America and Siberia. This supports the idea of a solar‐climate connection.
Causes and underlying processes of measurement variability in field erosion plots in Mediterranean conditions

An understanding of the sources of variation in the use of erosion plots and of their feasibility to meet the objectives of each specific research project is key to improving future field designs, selecting data for modelling purposes and furthering knowledge of soil erosion processes. Our own field experiences from ongoing research on soil erosion processes since 1989, have allowed us to detect several methodological problems that cause measurement variability. Here several examples are presented concerning: (i) differences in long‐term soil erosion data between open and closed plots; (ii) differences in soil loss derived from replica soil erosion plots; and (iii) differences in soil loss data derived from plots at a range of spatial scales. Closed plots are not the most suitable method for long‐term monitoring of soil erosion rates due to the risk of exhaustion of available material within the plot. The difference in time after which exhaustion occurs depends on the surface soil characteristics, the climatological conditions and the size of the plots. We detected four and seven years as ‘time to exhaustion’. Different results are frequently obtained between pairs of replica plots. Differences up to a factor of nine have been detected in total soil loss between replica plots due to different spatial patterns of surface components. Different constraints appear depending on the spatial scale of measurement of soil loss. We obtained lower runoff percentages at coarser scales; however, larger sediment concentrations are observed at coarser scales (1·32 g l−1, catchment; 0·30 g l−1, 30 m2; 0·17 g l−1, 1 m2 scales). The smaller the plot, the larger the hydrological disconnection within the system, the lower the energy flows due to short distances and the quicker the response to runoff due to an artificial decrease of concentration times for continuous flow. Copyright © 2006 John Wiley & Sons, Ltd.
Explicit correction of ultrasonically determined elastic wave velocities for transducer‐bond phase shifts

Comparative experiments, in which either sample length or transducer configuration is varied, provide a reliable, accurate, and model-independent means of explicitly correcting ultrasonically determined elastic wave velocities, for transducer-bond phase shifts. The results of a number of such comparative experiments, employing both lithium niobate and quartz transducers on fused silica and aluminium samples, indicate that an absolute accuracy of order ±1 ns in travel time is routinely attainable. The use of these correction procedures in future ultrasonic studies should greatly improve the reliability of measured pressure and temperature derivatives of mineral elastic moduli and thereby facilitate more meaningful interpretation of seismic profiles for the earth's interior.
Ceramic discard and the use of space at Early Iron Age Ndondondwane, South Africa

Abstract There are few methods of ceramic analysis in accumulations research that can help distinguish discrete depositional areas and evaluate previous interpretations of activity organization at archaeological sites. This paper introduces a quantitative method of ceramic analysis that evaluates whether the fragmentation and functional variation of ceramic objects distinguish depositional areas resulting from different accumulation activities at early farming sites. Applied to the analysis of ceramics from the 9th–10th century A.D. site of Ndondondwane in South Africa, this study tests previous functional interpretations of the site and provides more detailed and dynamic ones for the activities contributing to the development of spatially and temporally discrete archaeological deposits during the main occupation of the settlement. This approach to the study of ceramic discard at Ndondondwane illustrates both a method as well as important caveats based on site formation and accumulations research that must be considered in attempts to interpret variation in the spatial organization of activities in past farming settlements in tropical Africa.
Melt inclusions track pre-eruption storage and dehydration of magmas at Etna

At Mount Etna, Italy, vigorous gas-rich eruptions in A.D. 2001, 2002, and 2003 were followed by gas-poor eruptions in 2004, 2006, and 2007. Analyses of volatile (CO2, H2O, S, Cl, F), semivolatile (Cu), and involatile (Nb, La) elements trapped in olivine-hosted melt inclusions from these latest eruptions reveal the effects of the sustained interaction between a percolating gas phase and the stored magma. Melt inclusion compositions indicate that magmas erupted from 2004 to 2007 were residual from the 2001–2003 eruptions, and show significant evolution in the volatile content of the melt. These melt inclusion observations, and variations in the C/S of volcanic gases, can be accounted for if melts reequilibrated with CO2-rich gases during storage and prior to entrapment as melt inclusions. Sustained gas percolation caused loss of water and enhancement of CO2 in the evolving melt and may strongly influence the behavior of Cu, which potentially partitions into the gas phase. Vapor-melt interactions during magma storage are important controls on magma evolution at persistently degassing volcanoes.
Early Holocene sea-level record from submerged fossil reefs on the southeast Florida margin

Massive fossil (outlier) reefs are preserved seaward of the modern shelf and reef tract along the southeast Florida margin. Thermal ionization mass-spectrometric (TIMS) U-Th dating of 16 pristine Acropora palmata and head corals cored from two transects document early Holocene reef growth from 8.9 to 5.0 ka, from approximately −13.5 to −7 m MSL (mean sea level). These samples fill a gap in the Florida Keys sea-level database and clarify the timing of a significant decrease in the rate of sea-level rise. A portion of this interval, represented by a gap in the Caribbean record of A. palmata reefs, has been interpreted as reef drowning during an inferred catastrophic sea-level rise event of >45 mm/yr, or a 6.5 m rise between 7.6 and 7.2 ka, attributed to West Antarctic Ice Sheet instability and changes in marine ice extent between 8 and 7 ka. Continuous in situ shallow-water reef growth in Florida during this interval precludes the occurrence of exceedingly rapid rates of sea-level rise and is consistent with the North Atlantic record of deglaciation from 9 to 7 ka. Gaps in the early Holocene sea-level records for Florida and the Caribbean are thus more likely to be artifacts of limited sampling and/or core coverage, and not necessarily a result of drowning.
Variable crustal thickness in the Oman ophiolite: Implication for oceanic crust

From 32 detailed cross sections through the gabbro unit of the Oman ophiolite, it is concluded that the thickness of this unit is on average 3.6 km. The lower layered gabbros represent two thirds, and the upper homogeneous foliated gabbros represent one third the gabbro unit. Assuming that the overlying basaltic lid (sheeted dikes and extrusives) is 1.5–2 km thick, the average crustal section in the Oman ophiolite is 0.5–1 km thinner than the standard 6-km-thick oceanic crust usually considered to be produced at fast spreading ridges, a point which is discussed. Variations in gabbro thickness between 5.4 km and 1.5 km are recorded. There is a general correlation throughout the ophiolite belt, particularly in the southeastern massifs, such that the thinnest gabbro units (2.2–2.5 km thick) overlay the thickest (300–700 m) transition zones which separate them from the mantle harzburgites and the thickest gabbro units (3.6–3.9 km thick) overlay the thinnest (5–100 m) transition zones. The combination of thinner gabbro units and thicker transition zones is observed above mantle diapirs or in domains which, following our structural models, were accreted above diapirs and have drifted in the spreading direction. If it is assumed that the extrusive basalt and the sheeted dike complex units have a constant thickness, such large variations indicate similar variations in the Moho level below the ridge of origin; in particular, the Moho above mantle diapirs should be some 1–1.5 km shallower than away from diapirs. As the Oman ophiolite is considered to derive from a fast spreading paleoridge, this doming should be detected in actual fast spreading ridges, as suggested by Barth and Mutter [this issue] and Wang et al. [this issue].
Main moisture sources affecting lower Yangtze River Basin in boreal summers during 2004–2009

This study presented a quantitative climatology of atmospheric moisture affecting the Yangtze River Basin (YRB) region in boreal summer season, as well as the spatial evolution of atmospheric moisture passage towards the target regions. A three‐dimensional Lagrangian particle dispersion model FLEXPART was driven by the National Centers for Environmental Prediction Final Operational Global Analysis data combined with a backtracking scheme, and the transport contributions to the moisture budget over the YRB region was identified through the continuous calculation of changes in specific humidity along the FLEXPART back trajectories of all air masses residing over this region for a period of six summers of year 2004–2009. The back trajectory analysis revealed four major moisture sources contributed to the YRB summer water vapour with different transport timescales: the East China Sea (17.5%), South China Sea (26.6%), Indian peninsula and the Bay of Bengal (20.5%) and Arabian Sea (13.6%). The properties of moisture sources and its transport processes are dominated by the Asian Summer Monsoon regimes. The Tibetan Plateau also acts as an effective barrier for the meridional moisture transport, leading to distinct moisture sinks at the southern slope. In contrast to the previous results, the tropical western Pacific only plays a minor role in the water vapour contributors. The importance of the four source areas varies over the summer: East and South China Sea sources persist throughout the summer, whereas the Indian peninsula, the Bay of Bengal and Arabian Sea sources reach the strongest moisture supply to the YRB region only in high summer (July), showing a close association with the March of Asian monsoon. The further evaluation shows that the inter‐annual variability of precipitation over YRB is strongly related to the moisture sources in the Bay of Bengal and Arabian Sea. Copyright © 2012 Royal Meteorological Society
Analysis of seasonal land use in Usangu wetlands, Tanzania: an object-oriented technique for multi-temporal analysis with high-resolution data

A multi-temporal analysis of Landsat panchromatic data was applied to the Usanga wetlands in Tanzania, where there are concerns that irrigated agricultural development is reducing downstream water availability. As there are many small fields, and even smaller areas of continuous vegetable cultivation throughout the year, 15-m resolution multi-temporal Landsat Enhanced Thematic Mapper Plus (ETM+) panchromatic data, acquired in the months of March, May and October, were used to extract information on the seasonal land use/cover in order to investigate agricultural water use. Object-oriented analysis was used to interpret these high-resolution data through definition of image segments, which were then classified using a pixel-based unsupervised classification method. This hybrid approach helps to process high-resolution data quickly and efficiently, so as to economically and effectively understand and classify land use/cover in highly heterogeneous and seasonally dynamic tropical conditions, where land units are typically small.
Methane flux in forested freshwater swamps of the southeastern United States

Methane emissions to the atmosphere from cypress swamp habitat in four wetland ecosystems of the southeastern United States range from 0.0046 to 0.068 gCH4m−2day−1. The possible causes for this range include differences in nutrient input and organic accumulation. These results indicate that existing data are inadequate to estimate the role of wetlands as a source of methane to the global troposphere.
Testosterona replacement therapy and prostate cancer: the collapse of a paradigm?

For six decades, it has been a part of the conventional medical wisdom that higher levels of testosterone increase the risk of prostate cancer. This belief is mostly derived from the well-documented regression of prostate cancer after surgical or pharmacological castration. However, there is an absence of scientific data supporting the concept that higher testosterone levels are associated with an increased risk of prostate cancer. Moreover, men with hypogonadism have substantial rates of prostate cancer in prostatic biopsies, suggesting that low testosterone has no protective effect against the development of prostate cancer. Moreover, prostate cancer rate is higher in elderly patients when hormonal levels are low. These results argue against an increased risk of prostate cancer with testosterone replacement therapy.
Conservation equations governing hillslope responses: Exploring the physical basis of water balance

A unifying approach for the derivation of watershed‐scale conservation equations governing hydrologic responses has recently been introduced. The approach is based on space‐time averaging of the corresponding point‐scale conservation equations over an averaging region called the representative elementary watershed (REW). The conservation equations are supplemented by constitutive relationships needed for the closure of various mass and momentum exchange terms. In this paper, we present a summary of the resulting equations for a somewhat simpler problem and show how these equations can be employed to model the long‐term water balance of a single, hypothetical REW. The governing equations are formulated in terms of an average saturation and a flow velocity of the unsaturated zone soils and the average thickness of the saturated zone soils. The equations are coupled ordinary differential equations and are nonlinear. Their solution is carried out simultaneously for a variety of combinations of watershed geometry, soil type, and atmospheric forcing. We show how a similarity analysis of the governing equations can lead to a general classification of REWs in terms of meaningful dimensionless similarity variables. In addition, we investigate the long‐term water balance and show that the governing equations are able to provide a realistic picture of the impact of changing climate, soil, and topographic controls on long‐term water balance.
High Sr/Y Magmas Reflect Arc Maturity, High Magmatic Water Content, and Porphyry Cu ± Mo ± Au Potential: Examples from the Tethyan Arcs of Central and Eastern Iran and Western Pakistan

The temporal and geochemical evolution of arc magmatism that culminated in porphyry Cu ± Mo ± Au deposit formation has been studied in three separate Neo-Tethyan arc systems in central and eastern Iran, and western Pakistan. Porphyry Cu-Au deposits in the Lut block of eastern Iran formed in the middle Eocene at the end of a period of extensive Paleocene-Eocene volcanism; porphyry Cu-Mo deposits in the Kerman belt of central Iran formed in the middle Miocene at the end of a period of voluminous Eocene-Oligocene volcanism; and porphyry Cu-Au deposits in the Chagai belt of western Pakistan formed in four pulses during the Eocene, early Miocene, middle-late Miocene, and late Miocene-Pliocene, after a prolonged period of arc magmatism that began in the Late Cretaceous (and is still active). In each region, the late porphyry-related magmas are more geochemically evolved and more hydrous (as evidenced by the presence of hornblende phenocrysts) than the preceding volcanic rocks. We suggest that this reflects maturation of the arc magmatic system over a period of tens of millions of years, leading to the generation of more evolved, volatile-rich magmas at later stages of the arc’s history. High magmatic water contents are a prerequisite for the shallow crustal emplacement of arc magmas and the subsequent generation of potentially ore-forming subvolcanic magmatic-hydrothermal systems. It is thus suggested that the fertility of arc magmas within a given arc terrane can be assessed by observing the relative timing of plutonic suites (later suites are more prospective), noting the common presence of hornblende or biotite phenocrysts (indicating high magmatic water contents), and through lithogeochemical fingerprinting of magmatic fractionation processes (relatively high Sr/Y and La/Yb ratios, and Eun/Eu* ratios ≈1, indicating abundant early hornblende fractionation and suppression of plagioclase crystallization in hydrous magmas).
Mapping intertidal sediment distributions using the RoxAnn System, Dornoch Firth, NE Scotland

Abstract The RoxAnn system (manufactured by Marine Micro Systems Ltd) is a remote sensing technique available for mapping sediment distributions. The acoustic returns from a standard boat-mounted echo sounder are electronically processed and the output stream logged together with accurate position data from a Differential Global Positioning System (or similar high accuracy positioning systems). The RoxAnn output comprises depth and indices of bed roughness (E1) and bed hardness (E2). The combination of these indices require to be translated into traditionally used parameters (such as visual appearance and sediment particle size) to provide useful mapping data. The most reliable means of achieving this is through a ground-truthing exercise, where grab samples and video footage are collected at sites of known RoxAnn values. Two problems are encountered in this process: firstly RoxAnn acoustic signatures often do not uniquely represent a specific bed type as described in traditional terms, secondly positioning errors can lead to poor calibration of the RoxAnn signatures in the ground truthing process. The first problem is difficult to correct, and can only be mitigated against through good survey design and execution. The second problem can be addressed in the data processing, and procedures for this are discussed. The RoxAnn data collected from the Dornoch Firth, used in conjunction with qualitative analysis of colour aerial photographs of the upper intertidal areas, provided a detailed classification of substrate types, including a classification of sands which allowed detailed insight into active processes of transport.
Structural and dynamic properties of soil organic-matter as reflected by 13C natural-abundance, pyrolysis mass-spectrometry and solid-state 13C NMR-spectroscopy in density fractions of an oxisol under forest and pasture

Changes in the content and isotopic composition of organic carbon as a consequence of deforestation and pasture establishment were studied in three neighbouring areas on an Oxisol from Australia and used to measure the turnover of forest-derived carbon (C3) under pasture (C4) over 35 and 83 year time scales. The results indicated that the quantity of forest-derived carbon declined rapidly during the first 35 years under pasture but the content remained nearly stable thereafter, suggesting the presence of two pools of carbon with different turnover times. The calculated values for turnover time of labile and resistant fractions of forest-derived carbon were 35 and 144 years respectively. The soil samples were separated into five fractions with densities 2.0 Mg m-3. Based on the spatial distribution of organic materials within the mineral matrix of soil, the soil organic matter contained in different density fractions was classified as free particulate organic matter (1.6 free), occluded particulate organic matter ( 2.0 Mg m-3). The 13C natural abundance showed that the free particulate organic matter formed a significant pool for soil organic matter turnover when the forest was replaced by pasture. Compared with free particulate organic matter, the organic materials occluded within aggregates had slower turnover times. The occluded organic materials were in different stages of decomposition and had different chemical stabilities. Comparison of the chemistry and isotopic composition of occluded organic materials indicated that the O-alkyl C content of the occluded organic materials was inversely related to their stabilities whereas their aromatic C content was directly related to their stabilities. In soils under pasture, a considerable amount of forest-derived carbon was associated with clay particles in the fractions . 2.0 Mg m-3. The rate of accumulation of pasture-derived carbon was also rapid in this fraction, indicating the presence of two different pools of carbon (C3 and C4) associated with clay particles. The forest-derived carbon had the highest stability in the fractions >2.0 Mg m-3, probably due to strong interaction with active aluminium or iron and aluminium oxides associated with clay surfaces.