依靠科技进步 发展天然气工业

一、对我国石油天然气工业发展历史、现状、前景的评估 1、世界天然气工业,从50年代以来迅速发展。1950年世界剩余探明储量为8.5万亿m~3,1988年初已达111.9万亿m~3。其探明储量大约每十年翻一番。据十二届世界石油大会(1987年,美国休斯敦)资料介绍,尚可寻找的储量为119万亿m~3。以目前年产约1.5～1.8万亿m~3(有人预测2020年年产可达2.0万亿m~3)计算,世界天然气储量可维持开采100年以上。从全球来看,在可望的未来,天然气仍是不可替代的重要能源和化工原料。天然气工业仍处于蓬勃发展的趋势。     

A planet in transition: The onset of plate tectonics on Earth between 3 and 2 Ga?

Many geological and geochemical changes are recorded on Earth between 3 and 2 Ga.Among the more important of these are the following:(1)increasing proportion of basalts with"arc-like"mantle sources;(2)an increasing abundance of basalts derived from enriched(EM)and depleted(DM)mantle sources;(3)onset of a Great Thermal Divergence in the mantle;(4)a decrease in degree of melting of the mantle;(5)beginning of large lateral plate motions;(6)appearance of eclogite inclusions in diamonds;(7)appearance and rapid increase in frequency of collisional orogens;(8)rapid increase in the production rate of continental crust as recorded by zircon age peaks;(9)appearance of ophiolites in the geologic record,and(10)appearance of global LIP(large igneous province)events some of which correlate with global zircon age peaks.All of these changes may be tied directly or indirectly to cooling of Earth's mantle and corresponding changes in convective style and the strength of the lithosphere,and they may record the gradual onset and propagation of plate tectonics around the planet.To further understand the changes that occurred between 3 and 2 Ga,it is necessary to compare rocks,rock associations,tectonics and geochemistry during and between zircon age peaks.Geochemistry of peak and inter-peak basalts and TTGs needs to be evaluated in terms of geodynamic models that predict the existence of an episodic thermal regime between stagnant-lid and plate tectonic regimes in early planetary evolution.     

Insight into interactions of olivine-scCO2-water system at 140 °C and 15 MPa during CO2 mineral sequestration

CO₂ mineral sequestration (in ultrabasic or basaltic rocks) has been considered as a promising long-term and stable approach to reduce CO₂ in the atmosphere and would counteract the effect of global warming. Meanwhile, clays are widely found in ultrabasic reservoirs. In our study, clays were observed in natural olivine samples, which were used for laboratory experiments in a supercritical CO₂ system at 140 °C and 15 MPa. Initial olivine samples were crushed into two sizes which were large grains of ∼850–1000 μm and powder particles of ∼75–150 μm, with the durations of 400 and 1000 h for the powder and grains, respectively. The results showed amorphous silica was newly formed and this passivating layer could mitigate the water-rock interaction to some extent, but it would not play a long-term prohibited effect on secondary mineral carbonate formation as it is a Fe(III) free silica coating. More interestingly, the secondary carbonates were observed to form near the surface sites where locates more clays. Our findings provide insights into the reaction mechanisms of olivine-scCO₂-water interaction process in natural ultrabasic rocks.     

Genetic link between saline and carbonatitic mantle fluids: The system NaCl-CaCO3-MgCO3 ± H2O ± Fe0 at 6 GPa

Melt inclusions in kimberlitic minerals and diamonds indicate that chlorides are important constituents of mantle carbonatite melts. Besides, alkaline chlorides are important constituents of saline high-density fluids (HDFs) found in diamonds from kimberlites and placers around the world. Continuous compositional variations suggest that saline and carbonatitic HDFs could be genetically linked. However, the essence of this link remains unclear owing to the lack of data on phase relations in the chloride-carbonate systems under pressure. Here we studied subsolidus and melting phase relations in the system NaCl–CaCO₃–MgCO₃ at 6 GPa and 1000–1600 °C using a Kawai-type multianvil press. We found that at 1000 °C, subsolidus assemblage consists of halite, magnesite, and aragonite. At higher temperatures, the stabilization of dolomite splits the subsolidus area into two partial ternary fields: halite + magnesite + dolomite and halite + dolomite + aragonite. The minimum on the liquidus surface corresponds to the halite-dolomite-aragonite ternary eutectic, situated at 1100 °C. The eutectic melt has Ca# 89 and contains 30 wt.% NaCl (26 mol% 2NaCl). The system has two ternary peritectics: halite + dolomite = magnesite + liquid located near the ternary eutectic and magnesite + dolomite = Mg-dolomite + liquid situated between 1300 and 1400 °C. Although under dry conditions incipient melting yields carbonate-dominated melt, the addition of water facilitates the fusion of NaCl and expands the liquid field to NaCl-rich compositions with up to 70 wt.% NaCl. The obtained results favor the idea that hydrous saline melts/fluids (brines) found as inclusions in diamonds could be a lower temperature derivative of mantle carbonatite melts and disagree with the hypothesis on chloride melt generation owing to the chloride-carbonate liquid immiscibility since no such immiscibility was established. We also studied the interaction of the NaCl–CaCO₃–MgCO₃ system with iron metal and found that carbonate reduction produces C-bearing species (Fe⁰, Fe-C melt, Fe₃C, Fe₇C₃, C⁰) and wüstite containing Na₂O, CaO, and MgO. Besides, a carbonate chloride compound, Ca₂Cl₂CO₃, was established among the reaction products. The interaction between NaCl-bearing carbonate melt shifts its composition toward Mg-poor and NaCl-rich. Given the above, an alternative hypothesis can be proposed, according to which the interaction of alkaline chloride-bearing carbonate melts formed in the subduction zones with the reduced mantle should be accompanied by diamond crystallization and shift the composition of the melt from carbonatitic to alkali-rich saline.     

Dolomite microstructures between 390° and 700 °C: Indications for deformation mechanisms and grain size evolution

Dolomitic marble on the island of Naxos was deformed at variable temperatures ranging from 390 °C to >700 °C. Microstructural investigations indicate two end-member of deformation mechanisms: (1) Diffusion creep processes associated with small grain sizes and weak or no CPO (crystallographic preferred orientation), whereas (2) dislocation creep processes are related with larger grain sizes and strong CPO. The change between these mechanisms depends on grain size and temperature. Therefore, sample with dislocation and diffusion creep microstructures and CPO occur at intermediate temperatures in relative pure dolomite samples. The measured dolomite grain size ranges from 3 to 940 μm. Grain sizes at T_max >450 °C show an Arrhenius type evolution reflecting the stabilized grain size in deformed and relative pure dolomite. The stabilized grain size is five times smaller than that of calcite at the same temperature and shows the same Arrhenius-type evolution. In addition, the effect of second phase particle influences the grain size evolution, comparable with calcite. Calcite/dolomite mixtures are also characterized by the same difference in grain size, but recrystallization mechanism including chemical recrystallization induced by deformation may contribute to apparent non-temperature equilibrated Mg-content in calcite.     

Response of 1 × 2 pile group under eccentric lateral loading

A large scale model test of a 1 × 2 pile group was conducted in silts to investigate its behavior under eccentric lateral loading. The model pile group consisted of two well instrumented steel piles and was installed in a large soil tank with a close spacing of three-pile diameters on centers. The test results revealed that the eccentricity of lateral loads had limited effect on the overall performances of the 1 × 2 pile group, but significantly contributed to the unevenness of internal forces of the individual piles. The coupling effect between the lateral deflection and torque gave rise to the substantial increase in the torsional resistance of individual piles within the group, comparing to that of a torsionally loaded single pile. The contribution provided by the torsional resistances of individual piles in resisting the external torque continually decreased when the applied lateral load increased. In addition, a three-dimensional finite-element analysis for the pile group was performed and the simulated response was found to be in good agreement with the measured test results. Based on the same model, more cases with different loading conditions were further analyzed. It could be concluded from the analyses that the layout of individual piles within the group obviously affected the behavior of the 1 × 2 pile group under eccentric lateral loads.     

Geology and geochronology of the Betara region in south-southeastern Brazil: Evidence for possible Statherian (1.80–1.75 Ga) and Calymmian (1.50–1.45 Ga) extension events

The results of geological mapping, chemical analysis and radiometric dating of metabasic rocks of Betara Formation, and mapping and dating of those present in the Betara basement nucleus together with mylonitic granodiorite and syenogranite are reported here. U–Pb analysis of bulk zircon fractions from the metabasic rocks of the basement nucleus yielded a Statherian age of 1790 ± 22 Ma, while the metabasic rocks from the upper part of the Betara Formation yielded a Calymmian age between 1500 and 1450 Ma. This age is a minimum for the deposition of the Betara Formation. The older metabasic rocks are associated with post-tectonic, possibly anorogenic syenogranite, while the younger ones are gabbro or very porphyritic ankaramite whose REE patterns are consistent with crystallization from an N-MORB parent magma. The observations and data point to the probable events associated with extensional processes of the end of Paleoproterozoic and early Mesoproterozoic. Similar registers of Statherian (1.80–1.75 Ga) and Calymmian (1.50–1.45 Ga) extensional events are recorded in other parts of the South American and African continents. The Neoproterozoic witnessed the formation and junction of the tectonic slices which formed the Apiaí domain during the assemblage of western Gondwana.     

An experimental study of hydroxo complex formation in basic and near-neutral solutions of rare-earth elements and yttrium at 25 ºC

We have studied the hydrolytic behavior of Y^3 + and trivalent ions of rare earth elements in aqueous solutions at 25 ºC. The stepwise stability constants of hydroxide complexes were measured by spectrophotometry, using m-cresol purple and 1-(2-pyridylazo)-2-naphthol as pH indicators at an ionic strength no more than 0.0005. The results showed that at pH ranging between 6.0 and 11.0 in freshly prepared solutions of REE trichlorides, lanthanides are presented as Ln3 +, Ln(OH)2 +, Ln(OH)2, and Ln(OH)3. The plots of the formation constants of + 0 monohydroxo complexes of 4f n ions M^3 + versus atomic number Z deviate from smooth ones and consist of four convex curves. This phenomenon is also observed in normalized spectra of REE concentrations in natural objects and is known as the tetrad effect. The obtained data give an insight into the relationship between REE complex formation and REE fractionation in geochemical processes and can be used for physicochemical modeling of geochemical systems.     

Petrogenesis and tectonic significance of the ∼ 850 Ma Gangbian alkaline complex in South China: Evidence from in situ zircon U–Pb dating,Hf–O isotopes and whole-rock geochemistry

The Gangbian alkaline complex in the southeastern Yangtze Block (South China) is composed of Si-undersaturated pyroxene syenites and Si-saturated to -oversaturated syenites and quartz monzonites. SIMS zircon U–Pb analyses indicate that the complex was emplaced at 848 ± 4 Ma, during a previously-recognized interval of magmatic quiescence between the ca 1.0–0.89 Ga Sibaoan orogenic magmatism and the ca 0.83–0.78 Ga magmatic flare-up. The Gangbian rocks are characterized by wide, coherent variations in major and trace elements (SiO₂ = 47.6–68.4%, K₂O + Na₂O = 4.5–10.5%, K₂O/Na₂O = 0.4–1.2, MgO = 1.2–8.5%, Cr = 4.5–239 ppm, and Ni = 4.5–143 ppm) and by enrichment in LIL and LREE and depletion in Nb, Ta and P in trace element spidergrams. Their whole-rock εNd(T) (? 6.5 to ? 0.4) and εHf(T) (? 10.7 to 0.4) are positively correlated, suggesting involvement of both metasomatized mantle and continental crust materials in their genesis. In situ zircon Hf–O isotopic measurements for the most evolved quartz monzonite sample yield a binary mixing trend between the mantle- and supracrustal-derived melts. It is suggested that the pyroxene syenites were derived by partial melting of metasomatized, phlogopite-bearing lithospheric mantle, and the parental magma experienced extensive fractionation of pyroxene and olivine associated with varying degrees of crustal contamination. Subsequent fractional crystallization of hornblende and minor amounts of plagioclase from the alkali basaltic magmas, accompanied by crustal contamination, produced the Si-saturated to -oversaturated syenites and quartz monzonites. These ca. 0.85 Ga alkaline rocks and neighboring contemporaneous dolerite dykes are the products of the anorogenic magmatism after the Sibao Orogeny. They post-date the final amalgamation between the Yangtze and Cathaysia Blocks, most likely manifesting the initial rifting of South China within the Rodinia supercontinent.     

In situ AFM study on barite (0 0 1) surface dissolution in NaCl solutions at 30 °C

This paper reports in situ observations on barite (0 0 1) surface dissolution behavior in 0.1–0.001 M NaCl solutions at 30 °C using atomic force microscopy (AFM). The step retreating on barite (0 0 1) surfaces changed with increasing NaCl solution concentrations. In solutions with a higher NaCl concentration (⩾0.01 M), many steps showed curved or irregular fronts during the later experimental stage, while almost all steps in solutions with a lower NaCl concentration exhibited straight or angular fronts, even during the late stage. The splitting phenomenon of the initial 〈h k 0〉 one-layer steps (7.2 Å) into two half-layer steps (3.6 Å) occurred in all NaCl solutions, while that of the initial [0 1 0] one-layer steps observed only in the 0.1 M NaCl solution. The step retreat rates increased with an increasing NaCl solution concentration. We observed triangular etch pit and deep etch pit formation in all NaCl solutions, which tended to form late in solutions with lower NaCl concentrations. The deep etch pit morphology changed with increasing NaCl solution concentrations. A hexagonal form elongated in the [0 1 0] direction was bounded by the {1 0 0}, {3 1 0}, and (0 0 1) faces in a 0.001 M NaCl solution, and a rhombic form was bounded by the {5 1 0} and (0 0 1) faces in 0.01 M and 0.1 M NaCl solutions. An intermediate form was observed in a 0.005 M NaCl solution, which was defined by {1 0 0}, a curved face tangent to the [0 1 0] direction, {3 1 0}, and (0 0 1) faces: the intermediate form appeared between the hexagonal and rhombic forms in solutions with lower and higher NaCl concentrations, respectively. The triangular etch pit and deep etch pit growth rates also increased with the NaCl solution concentration. Combining the step and face retreat rates in NaCl solutions estimated in this AFM study as well as the data on the effect of water temperature on the retreat rates reported in our earlier study, we produced two new findings. One finding is that the retreat rates increase by approximately two-fold when the NaCl solution concentration increases by one order of magnitude, and the other finding is that the retreat rate increase due to a one order of magnitude increase in the NaCl concentration corresponds to an increase of approximately 8 °C in water temperature. This correlation may help to understand and evaluate increasing dissolution kinetics induced by the different mechanisms where barite dissolution is promoted by the catalytic effect of Na⁺ and Cl⁻ ions (through an increase in the NaCl solution concentration) or by an increase in the hydration of Ba²⁺ and SO₄²⁻ (through an increase in water temperature).     

Hydrosulfide/sulfide complexes of zinc to 250 °C and the thermodynamic properties of sphalerite

The solubility of synthetic ZnS_(cr) was measured at 25–250 °C and P = 150 bars as a function of pH in aqueous sulfide solutions (~ 0.015–0.15 m of total reduced sulfur). The solubility determinations were performed using a Ti flow-through hydrothermal reactor. The solubility of ZnS_(cr) was found to increase slowly with temperature over the whole pH range from 2 to ~ 10. The values of the Zn–S–HS complex stability constant, β, were determined for Zn(HS)₂⁰_(aq), Zn(HS)₃^?, Zn(HS)₄^2?, and ZnS(HS)^?. Based on the experimental values the Ryzhenko–Bryzgalin electrostatic model parameters for these stability constants were calculated, and the ZnS_(cr) solubility and the speciation of Zn in sulfide-containing hydrothermal solutions were evaluated. The most pronounced solubility increase, about 3 log units at m(S_total) = 0.1 for the temperatures from 25 to 250 °C, was found in acidic solutions (pH ~ 3 to 4) in the Zn(HS)₂⁰_(aq) predominance field. In weakly alkaline solutions, where Zn(HS)₃^? and Zn(HS)₄^2? are the dominant Zn–S–HS complexes, the ZnS_(cr) solubility increases by 1 log unit at the same conditions. It was found that ZnS(HS)^? and especially Zn(HS)₄^2? become less important in high temperature solutions. At 25 °C and m(S_total) = 0.1, these species dominate Zn speciation at pH > 7. At 100 °C and m(S_total) = 0.1, the maximum fraction of Zn(HS)₄^2? is only 20% of the total Zn concentration (i.e. at pH_t ~ 7.5), whereas at 350 °C and 3 <pH_t <10, the fraction of Zn(HS)₄^2? and ZnS(HS)^? is less than 0.05% and 2.5% respectively, of the total Zn concentration and Zn(HS)₂⁰ and Zn(HS)₃^? predominate. The measured equilibrium formation constants were combined with the literature data on the stability of Zn–Cl complexes in order to evaluate the concentration and speciation of Zn in chloride solutions. It was found that at acidic pH, and in more saline fluids having total chloride > 0.05 m, Zn–Cl complexes are responsible for hydrothermal Zn transport with no significant contribution of Zn–S–HS complexes. The hydrosulfide/sulfide complexes will play a more important role in lower salinity (< 0.05 m chloride) hydrothermal solutions which are characteristic of many epithermal ore depositing environments. The value of Δ_fG° (β-ZnS_(cr)) = ? 198.6 ± 0.2 kJ/mol at 25 °C was determined via solubility measurements of natural low-iron Santander (Spain) sphalerite.     

Glaciation and ~ 770 Ma Ediacara (?) Fossils from the Lesser Karatau Microcontinent,Kazakhstan

The Cambrian explosion, c. 530–515 Ma heralded the arrival of a diverse assembly of multicellular life including the first hard-shelled organisms. Fossils found in Cambrian strata represent the ancestors of most modern animal phyla. In contrast to the apparent explosiveness seen in the Cambrian fossil record, studies of molecular biology hint that the diversification observed in Cambrian strata was rooted in ancestry extending back into the Ediacaran (635–542 Ma). Fossil evidence for this mostly cryptic phase of evolution is derived from the soft-bodied fossils of the Ediacaran biota found throughout the world and bilaterian embryos found in the Doushantuo lagerstätte in South China. The first appearance of Ediacara fauna is thought to have followed the last of the ~ 750–635 Ma Neoproterozoic glacial episodes by 20–30 million years. In this paper, we present evidence for the oldest discovery of the ‘Ediacara’ discoidal fossils Nimbia occlusa and Aspidella terranovica (?) that predate the early Cryogenian glaciations by more than fifty million years. There is considerable disagreement over the significance of discoidal Ediacaran fossils, but our findings may support earlier suggestions that metazoan life has roots extending deeper into the Proterozoic Eon. We also confirm the presence of a Late Cryogenian (e.g. “Marinoan”) glaciation on the Lesser Karatau microcontinent including dropstones and striated clasts within the glacial strata.     

U–Pb and Re–Os isotopic systematics and zircon Ce4 +/Ce3 + ratios in the Shiyaogou Mo deposit in eastern Qinling,central China: Insights into the oxidation state of granitoids and Mo (Au) mineralization

The newly-discovered Shiyaogou molybdenum deposit is located in the eastern Qinling metallogenic belt in central China. The deposit contains at least 152,000 t of Mo metal and bears typical porphyry-type features in terms of its concentric alteration zonation, quartz vein-hosted Mo mineralization, veining sequence and the spatial association with concealed granite porphyries. Re–Os isotope analyses of molybdenite from the deposit yield an ore-forming age of 132.3 ± 2.8 Ma. LA-ICP-MS U–Pb zircon dating of ore-related porphyries yields crystallization ages from 135 Ma to 132 Ma, indicating a temporal link between granitic magmatism and Mo mineralization. A population of captured magmatic zircons indicates another pulse of magmatism at ~ 143 Ma. A barren granite intrusion near the deposit gives a zircon U–Pb age of 148.1 ± 1.1 Ma. These magmatic activities were concurrent with the emplacement of the nearby Heyu granitic batholith, a largely ore-barren intrusive complex formed from ~ 148 Ma to ~ 127 Ma. Zircon Ce^4 +/Ce^3 + ratios of ore-related porphyries are obviously higher than those of contemporaneous barren granitoids, implying an affinity between Mo mineralization and highly oxidized magmas. Moreover, zircons from these granitoids overall have decreasing Ce^4 +/Ce^3 + ratios from 148 Ma to 132 Ma, reflecting decreasing oxygen fugacities during magma evolution. Available geological, radiometric and stable isotopic evidence suggests that the decrease of magma oxygen fugacity was probably associated with an increase of mantle contribution to granitic magmatism and metallogenesis, which probably gave rise to successive mineralization of Mo and Au in the eastern Qinling. The intense magmatic–metallogenic events in the eastern Qinling during Late Jurassic to Early Cretaceous times are interpreted as a response to the large-scale lithosphere thinning and subsequent asthenosphere upwelling beneath the eastern part of the North China Craton.     

530 Ma syntectonic syenites and granites in NW Namibia — Their relation with collision along the junction of the Damara and Kaoko belts

The Lower Ugab and Goantagab structural domains are located at the junction between the N–S trending Kaoko and the E–W trending Damara belts (NW Namibia), where Neoproterozoic metavolcano-sedimentary sequences were intruded by several syenitic/granitic plutons. We present here new U–Pb ages on zircon grains from the Voetspoor and Doros plutons. Together with petrological, geochemical and structural data we evaluate the timing of the deformation and relation to the geodynamics during the final stage of Gondwana amalgamation.The plutons are composed of three main rock types: hornblende quartz-syenite, syenodiorite and biotite granite. The two former are predominant and show genetic correlation such as magma mingling structures and similar geochemical signatures. The biotite granite occurs in the SW parts of the intrusions and clearly cuts the syenitic rocks. Although the plutons are mainly isotropic, the structures around them demonstrate that their intrusion occurred during a second deformation phase (D2) with a component of sinistral solid state rotation with respect to the wall rocks in response to D2 transpression. Four samples were dated using U–Pb SHRIMP methodology in single zircon grains. A hornblende monzodiorite from the Voetspoor pluton yielded an age of 534 ± 4.5 Ma. A hornblende monzonite from the Doros pluton produced an age of 528 ± 5 Ma. The biotite granite facies was sampled in the Doros intrusion and yielded an age of 530 ± 4.5 Ma. In addition, a granitic vein folded by D2 close to the northeastern contact of the Doros pluton with the encasing phyllites (Amis River Formation) was also dated, yielding an age of 533 ± 6 Ma. The data show that all granite–syenite from Doros and Voetspoor intrusions are contemporaneous and crystallized in the period between 539 and 522 Ma within the errors. D1–D2 deformational phases took place under greenschist facies (biotite zone) conditions and during D3 the metamorphic grade was slightly lower. We interpret that the plutons are coeval to peak metamorphism of the region (530–520 Ma) and that D2 and D3 sinistral transpressional phases are due to collision in the Damara Belt. The E–W compressional event and second metamorphic episode in the Kaoko Belt occurred between 580 and 560 Ma and are apparently unrelated to the thermo-tectonic evolution described here, although D1 might be partially related to this event. The sinistral transpressional D2 phase resulted probably from the position of the area considered at the junction between the belts, and not in the frontal Damara collision further to the east. This new interpretation is consistent with the Ar–Ar ages for the region (about 500 Ma), interpreted to reflect cooling of the orogen. The enrichment in LREE, K, Rb, Ba and Sr, and depletion in Nb of these basic to intermediate alkalic rocks could indicate that they partially derived from melting of a subcontinental lithospheric mantle that was affected by subduction and the granitic rock types represent lower crust contamination. We interpret that they could be related to heating in the mantle caused by asthenosphere influx in a zone of slab-breakoff during collision between Kalahari and Congo cratons.     

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

Acta Geochimica - Kyanite is an important and slow-dissolving mineral. Earlier work has measured its dissolution rate at high temperature and acidic pH, but experimental measurements at low...     

The Holocene climatic optimum and pollen records of sapropel 1 in the eastern Mediterranean, 9000–6000 BP

The most recent sapropel in the deep eastern Mediterranean Sea has been deposited between 9 and 6 ka bp. Climate conditions, as revealed by the pollen records of this sapropel in marine cores, were most favorable for temperate deciduous trees, which is in agreement with the inferences from records of peripheral land pollen sites. The abundance of deciduous oak pollen is much higher than that of Artemisia (sage-brush), indicating that annual precipitation in the mid-elevation borderlands was at least 550 mm without summer drought, but more probably in the range 800–1300 mm. The pollen of Pistacia, which formed a savanna at low elevations, is also at its highest abundance and signals the absence of frost in winter, while being capable of withstanding summer drought. The early Holocene therefore appears as the post-glacial climatic optimum with the highest moisture and mildest winters. In southwest Asia, this is also the time of the Neolithic population explosion with incipient domestication of cereals, possibly following natural selection of the ‘tough rachis’ mutation in wheat and barley by the extreme aridity of the preceding Younger Dryas.     

Soil water retention behavior and microstructure evolution of lateritic soil in the suction range of 0–286.7 MPa

Acta Geotechnica - This paper presents an experimental investigation of the soil water retention curve (SWRC) and volume change curve over a large suction range (0–286.7&nbsp;MPa), and...