Hasil untuk "Mineralogy"

Mohamed Amine Es-Soufi, Jacqueline Saliba, Arnaud Lafourcade et al.

The shrink-swell behavior of clayey soils is a major concern in geotechnical engineering, particularly due to its role in the formation of desiccation cracks that undermine the structural integrity of road pavements. This study investigates the shrinkage and desiccation-induced cracking behavior of three different clayey soils: a swelling clay (calcium-rich Bentonite), a non-swelling clay (Kaolinite), and a clayey soil sampled from the cracked RD105 marsh road in Southwest France (Esnandes). Linear shrinkage tests (NF P 94–060–2) and 2D Digital Image Correlation (DIC-2D) were employed to monitor and quantify shrinkage deformation and crack propagation during desiccation. Microscopic (SEM/EDS) and mineralogical (XRD) analyses provided insights into the material properties influencing desiccation behavior. The results revealed substantial differences among the soils. Bentonite exhibited the highest volumetric shrinkage (47 %) and the most extensive cracking, characterized by a Crack Surface Ratio (CSR) of 32 % and an average crack width of 4.7 mm. Esnandes showed intermediate behavior, with 41 % volumetric shrinkage, a CSR of 14.5 %, and an average crack width of 3.5 mm. Kaolinite, by contrast, exhibited minimal shrinkage (16 %) and no significant cracking. The drying kinetics analysis indicated that Kaolinite reached its shrinkage limit within 1.4 days, Esnandes within 2.6 days, and Bentonite within 5.5 days. The final residual water content stabilized at 10 % for Bentonite, 3 % for Esnandes, and 0.1 % for Kaolinite. These findings highlight the critical role of soil mineralogy in governing shrinkage and cracking mechanisms, underscoring the importance of tailored stabilization strategies when constructing on expansive clayey soils.

Fernanda Magno Silva, Anita Fernanda dos Santos Teixeira, Marcelo Mancini et al.

In tropical regions, pedogenesis studies are challenging since most soils are polygenetic and studies on this approach are still lacking. Thus, complementary data is needed to understand their formation, which has been possible through proximal sensing tools. The objective of this study was to assess the efficiency of proximal sensing data to investigate the presence of lithological discontinuities and the within-profile variation of polygenetic soils formed from different parent materials and with varying weathering degrees. Soil morphology, texture, fertility, mineralogy, and reflectance analyses were conducted to characterize soil samples collected per horizon from five studied profiles. Additional samples were collected following a 15 x 15 cm grid and analyzed via portable X-ray fluorescence (pXRF) spectrometry. Parent material discontinuities were investigated through the ratios Ti/Zr, Si/Al, fine sand/coarse sand (FS/CS), and differences in the mineralogy of the sand, silt, and clay fractions. The five studied profiles were classified as: Fluvic Cambisol (CY), Sideralic Cambisol (CX), Xanthic Gibbsic Ferralsol (LA), Xanthic Ferralsol (LVA), and Rhodic Gibbsic Ferralsol (LV) per the World Reference Base (WRB/FAO) for Soil Resources. pXRF data revealed within-horizon variation of elemental contents. Chemical traits of anthropic and pedogenetic origin were successfully identified. The Ti/Zr ratio and mineralogical analysis of the sand, silt, and clay fractions were able to identify parent material discontinuities in LVA. By interpreting Vis-NIR spectra, it was possible to separate soils based on texture and mineralogy. Proximal sensor data, especially from pXRF, allowed for the detection of parent material discontinuities that were unapparent during field morphology analysis, contributing to improved details on soil genesis assessment and comprehension of previous soil formation events.

Emmy B. Hughes, Jacob J. Buffo, Frances Rivera‐Hernández et al.

Abstract Saline lakes are expected to have been extensively present on ancient Mars, particularly as the planet dried or cooled. Such lakes likely deposited sulfate salts, as these salts have been widely identified from orbital and in situ Mars data. However, the relationship between martian sulfates and the environmental conditions that formed them (including whether conditions were warm, cool, drying, or freezing), remains under‐characterized. To evaluate the relationship between sulfates and climate, we investigated the hypersaline, sulfate‐bearing Basque Lakes in British Columbia, Canada, which serve as an analog for both “cold and wet” and “warm and wet” early Mars. We use the rover and orbiter relevant instrument techniques of Raman, Near Infrared, and X‐Ray Fluorescence spectroscopy to evaluate seasonal lake mineralogy. We find that temperature‐dependent, multi‐cation salts form widely within the Basque Lakes' efflorescent crusts in the fall, which transform to meridianiite, mirabilite, a metastable Na‐sulfate 7‐hydrate, and epsomite in the wintertime. In both seasons, salt assemblages are metastable and persist beyond expected thermodynamic stability fields, suggesting ongoing climatic changes can prevent saline systems from settling into equilibrium phases. Coupled with sedimentological evidence, intimately mixed Mg‐sulfates of different hydration states could be an indicator of surface fluids that interacted with an atmosphere, while formation of Na‐sulfates could be evidence for brine freezing. Curiosity's exploration of the Gale crater sulfate‐bearing unit and Perseverance's exploration of Jezero crater on Mars offer excellent chances to investigate the influence of climate on Mg‐sulfate formation.

Ruana D. Brandão, Antônio M. de Freitas Júnior, José J. Linares et al.

This work concerns the preparation of Pt/AC catalysts (Pt supported on activated carbon) and their application to the synthesis of hydrocarbon biofuels through the HEFA (hydroprocessing of esters and fatty acids) route. The key motivation for the work was that catalysts based on sulfided Mo supported on γ-Al₂O₃, traditionally employed in the hydroprocessing of petroleum derivatives, (i) are unstable in the HDO (hydrodeoxygenation) of biomass-derived feedstocks and (ii) can contaminate the resulting biofuels with sulfur. In this context, a systematic study on the effects of preparation conditions on the properties of the resulting Pt/AC catalysts and their performance in HEFA was carried out for the first time. Efficient catalysts were obtained, which led to the complete deoxygenation of lauric acid and coconut oil, yielding products composed primarily of <i>n</i>-alkanes. The highest HDO activity was verified for the catalyst prepared using as a support an AC previously subjected to thermal treatment up to 800 °C in a H₂ atmosphere (which removed most of the surface acidic oxygenated groups), depositing Pt over the surface of this support via wet impregnation using a H₂PtCl₆ solution acidified with HCl. The obtained results showed the great potential of the Pt/AC catalysts for the production of hydrocarbon biofuels through the HEFA route.

S. Karunarathne, P.L. Dharmapriya, W.M.H.M. Wijesinghe et al.

The Mannar Basin is a rift basin formed during the breakup of Gondwana, comprising sedimentary deposits from multiple cycles. Exploration for hydrocarbons has uncovered igneous sequences distributed throughout the basin's sedimentary sequences. These sequences exhibit geochemical characteristics, typical for flood basalts formed during a series of eruptions from 60 to 62 Ma. Previous studies have focused on the petroleum system, tectonostratigraphy, lithostratigraphy, and the paleo-environmental setting, therefore, little was known about the petrogenesis of this flood basalt sequence. This study investigates the petrogenesis of the flood basalt sequence, focusing on crystallization temperature, source magma characteristics, and the nature of magma fractional crystallization. Additionally, it examines the mineralogical characteristics, including clay minerals, of the interstratified sedimentary layers to interpret their origins—an area that has not been previously studied in depth. Petrographic thin sections were prepared from unwashed drill cuttings taken from a depth of 4000–4200 m in the Barracuda petroleum exploration well. A detailed petrographic study was conducted on these samples to investigate the petrogenesis. Additionally, electron probe microanalysis (EPMA) was performed to determine the mineral chemistry of the basalt and interstratified sedimentary rock samples. The basalts are primarily composed of plagioclase (An62-82) and clinopyroxene (mostly augite), with minor occurrences of orthopyroxene (En54-67) and ulvöspinel. Only the lower-most basalt layers (4200–4210 m) contain olivine (Fo56-71). High-Al orthopyroxenes were observed in the shallower sequence. Mineral zoning and mineral chemical variations record fractional crystallization of the mafic magma. Together, these minerals reflect a complex magmatic evolution, where, initially, high-temperature conditions prevailed, followed by differentiation and fractional crystallization; a transition from primitive to more evolved conditions. Geothermometric calculations indicate crystallization temperatures of the basalt varying from 1330 to 1340 °C, typically associated with mantle-derived magmas and representing high-temperature magmatic processes.The interlayered sedimentary rocks within the basalt sequence are dark-coloured and consist of weathered feldspar and clinopyroxenes, with minor quartz and calcite. Powder x-ray diffraction (XRD) analyses reveal the presence of clay minerals such as smectite, antigorite, attapulgite, and chlorite in these sedimentary rocks. While unpublished reports suggest that the interlayered rocks are sandstones and shales (based on gamma-ray log data), these analyses indicate that they are volcaniclastic sediments resulting from the weathering of individual layers of the flood basalt sequence after their eruption.

T. Letulle, D. Gaspard, M. Daëron et al.

<p>Most of our knowledge of past seawater temperature history is based on <span class="inline-formula"><i>δ</i>¹⁸</span>O values of calcium carbonate fossil shells. However, the determination of past temperatures using this proxy requires the knowledge of past seawater <span class="inline-formula"><i>δ</i>¹⁸</span>O values, which is generally poorly constrained. Other paleothermometers using carbonate archives, such as <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Mg</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="8d51dfa4941e3d7b79a8ce41d2626020"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-1381-2023-ie00001.svg" width="37pt" height="14pt" src="bg-20-1381-2023-ie00001.png"/></svg:svg></span></span> ratios and clumped isotopes (<span class="inline-formula">Δ₄₇</span>), have been developed to allow for paleotemperatures to be estimated independently and to allow past ocean <span class="inline-formula"><i>δ</i>¹⁸</span>O values to be calculated using various groups of calcifying organisms. Articulated brachiopod shells are some of the most commonly used archives in studies of past oceanic geochemistry and temperature. They are abundant in the fossil record since the Cambrian, and for decades, their low Mg–calcite mineralogy has been considered relatively resistant to diagenetic alteration. Here, we investigate the potential of brachiopod shells as recorders of seawater temperatures and seawater <span class="inline-formula"><i>δ</i>¹⁸</span>O values using new brachiopod shell geochemical data by testing multiple well-established or suggested paleothermometers applied to carbonate archives.</p> <p>Modern articulated brachiopod shells covering a wide range of temperatures (<span class="inline-formula">−1.9</span> to 25.5 <span class="inline-formula">^∘</span>C), depths (5 to 3431 m) and salinities (33.4 to 37.0 PSU) were analysed for their stable isotope compositions (<span class="inline-formula"><i>δ</i>¹³</span>C, <span class="inline-formula"><i>δ</i>¹⁸</span>O and <span class="inline-formula">Δ₄₇</span>) and their elemental ratios (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Mg</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="93d9205225782a1f8841d5931bc9119e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-1381-2023-ie00002.svg" width="37pt" height="14pt" src="bg-20-1381-2023-ie00002.png"/></svg:svg></span></span>, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Sr</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="33pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="88479e7fe5ac264051dbc20ed4e5c89d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-1381-2023-ie00003.svg" width="33pt" height="14pt" src="bg-20-1381-2023-ie00003.png"/></svg:svg></span></span>, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Na</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="36pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="8b148d1480ad20f0f48f68de630bcb57"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-1381-2023-ie00004.svg" width="36pt" height="14pt" src="bg-20-1381-2023-ie00004.png"/></svg:svg></span></span> and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Li</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="31pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="308a6af7980b11d9d6b6ebcebc073fe7"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-1381-2023-ie00005.svg" width="31pt" height="14pt" src="bg-20-1381-2023-ie00005.png"/></svg:svg></span></span>). Our data allowed us to propose a revised oxygen isotope fractionation equation between modern-brachiopod shell calcite and seawater: </p><div class="disp-formula" content-type="numbered" id="Ch1.E1"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M16" display="block" overflow="scroll" dspmath="mathml"><mtable><mlabeledtr><mtd><mtext>(1)</mtext></mtd><mtd><mrow> <mi>T</mi> <mo>=</mo> <mo>-</mo> <mn mathvariant="normal">5.0</mn> <mo>(</mo> <mo>±</mo> <mn mathvariant="normal">0.2</mn> <mo>)</mo> <mo>(</mo> <msup> <mi mathvariant="italic">δ</mi> <mn mathvariant="normal">18</mn> </msup> <msub> <mi mathvariant="normal">O</mi> <mi mathvariant="normal">c</mi> </msub> <mo>-</mo> <msup> <mi mathvariant="italic">δ</mi> <mn mathvariant="normal">18</mn> </msup> <msub> <mi mathvariant="normal">O</mi> <mi mathvariant="normal">sw</mi> </msub> <mo>)</mo> <mo>+</mo> <mn mathvariant="normal">19.4</mn> <mo>(</mo> <mo>±</mo> <mn mathvariant="normal">0.4</mn> <mo>)</mo> <mo>,</mo> </mrow></mtd></mlabeledtr></mtable></math><div><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="416pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="dad0b18f89b626f929e4e5d67e76f980"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-1381-2023-e_1.svg" width="416pt" height="15pt" src="bg-20-1381-2023-e_1.png"/></svg:svg></div></div><p> where <span class="inline-formula"><i>δ</i>¹⁸</span>O<span class="inline-formula">_c</span> is in ‰ VPDB, <span class="inline-formula"><i>δ</i>¹⁸</span>O<span class="inline-formula">_sw</span> is in ‰ VSMOW, and <span class="inline-formula"><i>T</i></span> is in <span class="inline-formula">^∘</span>C. Our results strongly support the use of clumped isotopes as an alternative temperature proxy but confirm significant offsets relative to the canonical relationship established for other biogenic and abiogenic calcium carbonate minerals. Brachiopod shell <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M23" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Mg</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="5494b56141ea31f11a218bfc4b38b461"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-1381-2023-ie00006.svg" width="37pt" height="14pt" src="bg-20-1381-2023-ie00006.png"/></svg:svg></span></span> ratios show no relationship with seawater temperatures, indicating that this ratio is a poor recorder of past changes in temperatures, an observation at variance with several previous studies. Despite significant correlations with brachiopod living temperature, brachiopod shell <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M24" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Sr</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="33pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="3d09db9d2ca4d4697a1ddefedd348745"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-1381-2023-ie00007.svg" width="33pt" height="14pt" src="bg-20-1381-2023-ie00007.png"/></svg:svg></span></span>, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M25" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Na</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="36pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="eab88b5bbd423223e0768ab4cead9897"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-1381-2023-ie00008.svg" width="36pt" height="14pt" src="bg-20-1381-2023-ie00008.png"/></svg:svg></span></span> and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M26" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Li</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="31pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="2e539cc754540033ff93fd92d3e31cbb"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-1381-2023-ie00009.svg" width="31pt" height="14pt" src="bg-20-1381-2023-ie00009.png"/></svg:svg></span></span> values indicate the influence of environmental and biological factors unrelated to temperature, which undermines their potential as alternative temperature proxies. Kinetic effects (growth rates) could explain most of the deviation of brachiopod shell calcite from expected isotopic equilibrium with seawater and part of the distribution of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M27" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Sr</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="33pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="fcb882a35b990a83e39588a10abaf6f8"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-1381-2023-ie00010.svg" width="33pt" height="14pt" src="bg-20-1381-2023-ie00010.png"/></svg:svg></span></span>, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M28" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Na</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="36pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="36b471cad79683553095440c8036f8c3"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-1381-2023-ie00011.svg" width="36pt" height="14pt" src="bg-20-1381-2023-ie00011.png"/></svg:svg></span></span> and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M29" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Li</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="31pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="c6b229fe0d2ca5ac742a1f2d1a430b98"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-1381-2023-ie00012.svg" width="31pt" height="14pt" src="bg-20-1381-2023-ie00012.png"/></svg:svg></span></span> ratios.</p>

Yuxiao Xue, Deqing Zhu, Jian Pan et al.

This study is aimed to obtain better-quality Ni–Cr composite sinter for the production of 300 series stainless steel via the sintering-blast furnace process at lower cost. Based on the complementary advantages of limonitic nickel laterite and chromite, co-sintering pot tests of the two ores were conducted in various chromite proportions and then strengthened by multi-force fields. Mechanistic analysis was performed, including the chemistry and mineralogy of product sinter and the thermodynamic and kinetic conditions of the co-sintering process. The results indicate that the addition of chromite effectively improves tumble index and productivity, especially at a chromite ratio of 15%, due to the improvement of sinter microstructure and the thermodynamic and kinetic conditions during sintering. However, solid fuel rate is increased gradually because of the greater amount of high smelting minerals. With the application of multi-force fields, higher tumble index is obtained owing to the further densification of sinter bed and the formation of tighter interlocking texture. Solid fuel rate is greatly decreased due to the efficient supply of extra physical heat. Productivity is weakened to some extent as the flame fronts speed is reduced. In addition, excellent metallurgical performance is achieved. The co-sintering process of limonitic nickel laterite and chromite is significantly improved via multi-force fields.

José Nespereira, José Antonio Blanco, Mercedes Suárez et al.

The Dueñas Clay Formation is considered an example of a deposit of lacustrine continental origin. It is formed mainly by overconsolidated clays and includes feldspathic arenites, and clayey and silty levels; however, in geotechnical projects it is considered a clay unit and treated as a whole. The structure of each level was assessed in the field, in thin sections, and by SEM in the case of the clayey level. In addition, identification, strength, deformation, and durability tests were undertaken according to the nature of the samples (grain size analysis, Atterberg Limits, point load test, direct shear tests, uniaxial compression tests, swelling pressure, and unidimensional consolidation tests). The durability test was used as a criterion for dividing the levels within the formation according to their behavior as soil or rock. It was observed that the proportion and type of carbonate cementation controls the way in which the material behaves, with sparithic cement increasing the strength. The clay levels are expansive due to the presence of smectite, which also influences their behavior under shear stress. In addition, the massive and laminar structure of the layers caused by the continental conditions, in addition to the processes of post-sedimentation, explain their low compressibility.

رضا میکائیل, محمد عطایی, وحید سبزی et al.

<span lang="FA">انرژی مصرفی دستگاه</span><span dir="LTR">‌</span><span lang="FA">های برش</span><span dir="LTR">‌</span><span lang="FA">دهنده سنگ یکی از فاکتورهای مهم هزینه‌ساز در طی فرآیند برش سنگ</span><span dir="LTR">‌</span><span lang="FA">های ساختمانی است. با پیش‌بینی دقیق انرژی مصرفی دستگاه برش، علاوه بر تخمین هزینه</span><span dir="LTR">‌</span><span lang="FA">های برش، می‏توان به شرایط بهینه عملیاتی برش در جهت کاهش مصرف انرژی نزدیک شد. در این پژوهش، سعی شده است تا با استفاده از سیستم‏های طبقه‌بندی فازی چند فاکتوره، میزان قابلیت برش</span><span dir="LTR">‌</span><span lang="FA">پذیری سنگ‌های ساختمانی نرم را از دیدگاه شدت جریان مصرفی دستگاه برش اره با توجه به مشخصات فیزیکی و مکانیکی از قبیل مقاومت کششی برزیلی، درصد کوارتز محتوای سنگ، اندازه متوسط دانه، مقاومت فشارشی تک‌محوری، مدول یانگ و سختی موس مورد ارزیابی قرار داد. بدین منظور، پس از توسعه سیستم طبقه</span><span dir="LTR">‌</span><span lang="FA">بندی فازی، هفت نمونه سنگ ساختمانی کربناته شامل تراورتن آذرشهر، تراورتن حاجی‌آباد، تراورتن دره</span><span dir="LTR">‌</span><span lang="FA">بخاری، مرمریت هرسین، مرمریت صلصالی، مرمریت انارک و مرمریت هفتومان با استفاده از سیستم فازی ارایه ‌شده، رده</span><span dir="LTR">‌</span><span lang="FA">بندی شد و نتایج با میزان شدت جریان مصرفی دستگاه برش اره مورد ارزیابی و اعتبارسنجی قرار گرفت. نتایج حاصل از بررسی‏ها نشان داد که سیستم طبقه‌بندی فازی سه رده</span><span dir="LTR">‌</span><span lang="FA">ای، قادر به ارزیابی بهتری از قابلیت برش</span><span dir="LTR">‌</span><span lang="FA">پذیری سنگ</span><span dir="LTR">‌</span><span lang="FA">های ساختمانی نرم از دیدگاه برق مصرفی دستگاه برش سنگ است.</span>

Md Nahidul Hasan, Rumana Yeasmin, M. Julleh Jalalur Rahman et al.

Clay mineralogy and diagenesis affect the reservoir quality of the Neogene Surma Group in the Hatiya trough of Bengal Basin, Bangladesh. X-ray diffraction and scanning electron microscopic analyses of diagenetic clay minerals from Shahbazpur#2 well reveal that on average illite is the dominant clay mineral (50%), followed by chlorite (24%), kaolinite (23%) and smectite (2.50%). The absence of smectite at Core-2 (3259.80 m to 3269 m) results from the total transformation of smectite to illite owing to burial depth and high K–feldspar. The diagenetic changes are a result of chemical processes such as cementation, chlorite authigenesis, dissolution, alteration and replacement that have significantly affected the reservoir properties. Cementation plays an important role in reducing reservoir properties with pore and fracture filling cement. The relative percentage of illite and smectite minerals (>90% illite in I/S mixed layer) and Kübler index value (0.34° to 0.76° Δ2θ) indicate a diagenetic zone with subsurface temperatures of 120–180 °C in the studied samples. The temperature range determined using clay percentages and the Kübler index as a geothermometer is supported by observed diagenetic features such as quartz overgrowths, smectite to illite transformations and chlorite coatings. The diagenetic features cause variable reservoir porosity and permeability that are critical in planning exploration and development programs of this field or analog fields across the Bengal Basin.

Vincent Poirier, Isabelle Basile-Doelsch, Jérôme Balesdent et al.

Decomposing crop residues contribute to soil organic matter (SOM) accrual; however, the factors driving the fate of carbon (C) and nitrogen (N) in soil fractions are still largely unknown, especially the influence of soil mineralogy and autochthonous organic matter concentration. The objectives of this work were (1) to evaluate the retention of C and N from crop residue in the form of occluded and mineral-associated SOM in topsoil (0&#8722;20 cm) and subsoil (30&#8722;70 cm) previously incubated for 51 days with ¹³C-¹⁵N-labelled corn residues, and (2) to explore if specific minerals preferentially control the retention of residue-derived C and N in topsoil and subsoil. We used topsoil and subsoil having similar texture and mineralogy as proxies for soils being rich (i.e., topsoil) and poor (i.e., subsoil) in autochthonous organic matter. We performed a sequential density fractionation procedure and measured residue-derived C and N in occluded and mineral-associated SOM fractions, and used X-ray diffraction analysis of soil density fractions to investigate their mineralogy. In accordance with our hypothesis, the retention of C and N from crop residue through organo-mineral interactions was greater in subsoil than topsoil. The same minerals were involved in the retention of residue-derived organic matter in topsoil and subsoil, but the residue-derived organic matter was associated with a denser fraction in the subsoil (i.e., 2.5&#8722;2.6 g cm^&#8722;3) than in the topsoil (i.e., 2.3&#8722;2.5 g cm^&#8722;3). In soils and soil horizons with high clay content and reactive minerals, we find that a low SOM concentration leads to the rapid stabilization of C and N from newly added crop residues.

حامد فضلیانی, ابوالقاسم کامکار روحانی, علیرضا عرب امیری

آنالیز مولفه‌های مستقل (ICA) یک روش آماری چندمتغیره نسبتا جدید است که ابتدا برای مساله جداسازی کور منابع‌(BSS) و زمانی‌که هیچ اطلاعاتی درباره نحوه اختلاط منابع اولیه‌(سیگنال‌های مختلط‌شده) وجود ندارد و تنها شرط لازم استقلال آماری آنها است، ابداع شد. شرایطی مشابه مدل‌سازی پتانسیل معدنی که در آن برآیند فرآیندهای مستقل کانی‌زایی به‌صورت متغیرهای مشاهده‌شده‌ای همچون اطلاعات ژیوفیزیکی و ژیوشیمیایی در اختیار ما قرار می‌گیرد و ما اطلاعی درباره نحوه اختلاط آثار ژیوفیزیکی و ژیوشیمیایی کانی‌زایی‌های مختلف نداریم. در این مطالعه سعی برآن بوده است که روش تجزیه مولفه‌های مستقل به‌عنوان یک روش دانش‌محور مدل‌سازی پتانسیل معدنی معرفی شود. به‌این منظور ناحیه‌ای به وسعت 4800 کیلومتر مربع در جنوب نیشابور، شمال شرق ایران، برای تهیه نقشه پتانسیل معدنی ذخایر کرومیت انبانه‌ای مورد بررسی قرار گرفت. هم‌چنین، برای انجام این مطالعه از داده‌های ژیوشیمی رسوبات آبراهه‌ای، نقشه رخساره‌های افیولیتی، الگوی شکستگی‌های ناحیه‌ای و محدوده آلتراسیون‌های سرپانتینی موجود در منطقه، استفاده شد. نهایتا نتایج مدل‌سازی پتانسیل معدنی به‌روش تجزیه مولفه‌های مستقل با نتایج مطالعات ژیوشیمیایی تک‌متغیره و چند‌متغیره مقایسه و به‌روش تشخیص عملکرد نسبی‌(ROC) و با استفاده از موقعیت اندیس‌های شناخته‌‌‌شده موجود در منطقه، اعتبار‌‌سنجی شد. در این بررسی مساحت زیر نمودار ROC ، برابر با 967/0 بود که نشان‌دهنده عملکرد بسیار مطلوب مدل‌سازی انجام‌شده می‌باشد.

Şükrü ACAR

Bu çalışmada, yeni cinsler ve yeni türler tanımlanmıştır. Tanımlanan üç yeni cins; Neosistanites (tip tür Sistanites iranica), Parahaymanella (tip tür Parahaymanella hakyemezae) ve Pseudohottingerina (tip tür Pseudohottingerina burdurensis)’dir. Neosistanites yeni cinsi ve onun yeni türleri (N. sozerii, okuyucui, N. guvenci, N. dageri, N. catali, N. armagani, N. inali) ve Neosistanites iranicus tanımlanmıştır. Parahaymanella yeni cinsi ve onun yeni türleri (P. hakyemezae, P. bozkurti ve P. alanae)’ dır. Yeni cins Pseudohottingerina’nın yeni türleri (Ps. burdurensis ve Ps. yarisliensis)’dir. Laffitteina anatoliensis, Laffitteina thraciaensis, Sirtina paleocenica, Ankaraella minima yeni türleri ve Laffitteina erki, Laffitteina mengaudi, Ankaraella trochoidea türleri tanımlanmış ve resimlenmiştir. Bilinen Akbarina primitiva, Bolkarina aksarayi, Biloculinites cf. paleocenica,  Miscellanea? globularis, Globoflarina? sphaeroidea türleri ve Heterillina sp., Keramosphaera sp., Textularia sp., Chrysalidina? sp., Kolchidina? sp., Lockhartia? sp., Popovia? sp. ve Thalmannita? sp., cinsleri, sadece resimlenmiştir. Tanımlanamamış bentik foraminifer cinslerinin (miliolid, miscellanid, planulinid, rotaliid, mississippinid, aglutine) sadece fotoğrafları verilmiştir. Yeni bir ailenin (Neosistanitidae) tanımı, Neosistanites’in sınıflaması, cinsler arasında tip tür ve tür transferleri, Ankaraella cinsinin güncellenmesi ve Ankaraella trochoidea türü ile ilgili düzeltmeler yapılmıştır. Bazı fosil alglerin fotoğrafları, levhalarda verilmiştir. Tüm material (SBZ 2) Selandiyen’e aittir.

O. V. Bergal-Kuvikas, A. N. Rogozin, E. S. Klyapitsky

Based on the statistical data of the Global Volcanism Program of the Smithsonian Institution and published materials, we present a comparative analysis of caldera-forming eruptions on global scale. The geodynamic settings and genesis of the caldera-forming eruptions with basaltic-andesitic magma compositions are described. The origin of the majority of mafic ignimbrites was related with external water. Such ignimbrites were generated in a submarine environment or with a contact with water. The newly obtained data, paleogeodynamic reconstruction and geological mapping of Miocene mafic ignimbrites of the Eastern volcanic belt (EVB) of Kamchatka confirm their genesis in costal-marine environment. These new data show significance of paleoreconstructions in studies of paleo-volcanoes and relief-forming pyroclastic rocks.

Marius Stranghoener, Axel Schippers, Stefan Dultz et al.

The interaction of a single bacterial species (Burkholderia fungorum) with basaltic rocks from the ICDP HSDP2 drill core and synthetic basaltic glasses was investigated in batch laboratory experiments to better understand the role of microbial activity on rock alteration and Fe mobilization. Incubation experiments were performed with drill core basaltic rock samples to investigate differences in the solution chemistry during biotic and abiotic alteration. Additionally, colonization experiments with synthetic basaltic glasses of different Fe redox states and residual stresses were performed to evaluate their influence on microbial activity and surface attachment of cells. In biotic incubation experiments bacterial growth was observed and the release of Fe and other major elements from drill core basaltic rocks to solution exceeded that of abiotic controls only when the rock sample assay was nutrient depleted. The concentration of dissolved major elements in solution in biotic colonization experiments with synthetic basaltic glasses increased with increasing residual stress and Fe(II) content. Furthermore, the concentration of dissolved Fe and Al increased similarly in biotic colonization experiments indicating that their dissolution might be triggered by microbial activity. Surface morphology imaging by SEM revealed that cells on basaltic rocks in incubation experiments were most abundant on the glass and surfaces with high roughness and almost absent on minerals. In colonization experiments, basaltic glasses with residual stress and high Fe(II) content were intensely covered with a cellular biofilm. In contrast, glasses with high Fe(III) content and no residual stress were sparsely colonized. We therefore conclude that structurally bound Fe is most probably used by B. fungorum as a nutrient. Furthermore, we assume that microbial activity overall increased rock dissolution as soon as the environment becomes nutrient depleted. Our results show that besides compositional effects, other factors such as redox state and residual stress can control microbial alteration of basaltic glasses.

Yaroslav V. Kuzmin

The current situation with studies of prehistoric plant cultivation in the Russian Far East is presented. A critical analysis of existing concepts and models of the oldest agriculture in this region is also included. Reliable data allows us to conclude that humans in the southern Russian Far East (Primorye Province) began to cultivate millet at c. 4700–4600 BP (c. 3600–3400 calBC) in the context of the early Zaisanovka cultural complex of the Late Neolithic. The most probable source area for prehistoric agriculture in the Russian Far East was neighbouring Northeast China (Manchuria).

Gerardo Orozco-Melgar, Joaquín Proenza-Fernández, Jesús A. Blanco-Moreno et al.

La zona de Cayo Grande es parte del Macizo Moa-Baracoa, localizado en la parte más oriental de la faja Mayarí-Baracoa. En este trabajo se presentan y se discuten las características texturales, petrográficas, de quimismo mineral, de geotermometría catiónica, así como las implicaciones petrogenéticas de las rocas de afinidad ofiolítica presentes en la zona de Cayo Grande. Las características microestructurales de las dunitas impregnadas en la zona de estudio, indican condiciones de desequilibrio entre el olivino y la asociación plagioclasa+clinopiroxeno, y no presentan correlación entre los contenidos de forsterita y los de Ni en los olivinos. Esto es indicativo de la existencia de circulación magmática mediante flujo poroso en la zona. El orden de cristalización de los clinopiroxenos anterior a la plagioclasa, y la composición de las plagioclasas en las gabronoritas estudiadas en la zona de Cayo Grande, son indicativos de secuencias de acumulados en ofiolitas de zonas de suprasubducción, lo que sugiere un ambiente geodinámico en una zona de expansión de una cuenca de trasarco para las gabronoritas de la zona de Cayo Grande

A Arenas-Flores, E Cardoso-Legorreta, I Rivera-Landeros et al.

En el trabajo se presenta una alternativa a procesos convencionales de extracción y purificación de metales mediante la implementación de un proceso extractivo novedoso basado en la tecnología de membranas líquidas. Dicha técnica es una variante al proceso de extracción con solventes. En él se investiga la separación específica de hierro (II) y níquel (II) a partir de sulfatos empleando como portador (extractante) ácido di-2etilhexilfosfórico(D2EHPA) y queroseno como diluyente, a 25oC. La membrana líquida empleada en la experimentación presentó mejor respuesta para la extracción de Fe (II) que para Ni (II). El análisis de resultados permite afirmar que este proceso es de fácil aplicación en la extracción de los metales estudiados.

Ali UYGUN, Enis SOLAKOĞLU

Pütürge masifindeki pirofillit zuhurları düşük demir ve krom içerikleri nedeniyle giderek artan miktarlarda beyaz çimento üretiminde kullanılmaktadır. Pütürge güneyinde yaklaşık 15 km uzunluğunda bir kuşakta 25 dolayında pirofillit zuhuru saptanmış ve 10 ocak açılmıştır. Bazı kesimlerde yüksek alüminali distenli pirofillitlerin varlığı, pirofillitlerin masifin geçirdiği yeşilşist fasiyesindeki ikinci "gerileyen" metamorfizma evresinde distenlerden dönüştüğünü ortaya koymaktadır. Yüksek alüminali, serisitli, yüksek ve düşük silis modüllü ve düşük alkali içerikli olarak belirlenen beş ayrı tip pirofillit oluşumunun mineralojik ve jeokimyasal özellikleri tanımlanmıştır.

Mehmet AKARTUNA

Mit vorliegender Arbeit wurde die Fortsetzung der im Gebiet von Şile und Riva Deresi früher festgestellte Überschiebungslinie entlang des Bosporus endgültig nachgewiesen, die von jeher strittige Frage des Vorhandenseins der Überschiebung in der Umgebung von Sarıyer-Zekeriyaköy nochmals bestätigt, die zwischen der Sohle und den Abhängen der Tuffe von Maden Mahallesi (Tekneci Dere) vorhandenen und ebenfalls strittigen paläozoischen Ausbisse als tektonische Bildungen nachgewiesen und über deren Entstehung zwei neue Erklärungsarten in Vorschlag gebracht.