Hasil untuk "Mineralogy"

D. Green, A. .. Ringwood

R. Folk, P. Andrews, D. Lewis

C. E. Weaver, L. Pollard

J. Adams

G. Hanson

K. C. Lohmann

P. Jardine, J. McCarthy, N. L. Weber

J. Nicholls

Muhammad Andiva Pratama, Hasan Javed Khan

Abstract Reactive transport in porous media exhibits multifaceted interactions that are dependent on the matrix and fluid properties, and which ultimately alter these properties. A set of calcareous rock samples with unique mineralogy and varying petrophysical properties are selected for this study. A capillary rise experiment is performed in each sample, first with deionized water and then with a dilute, pH 2, HCl solution. Pre‐ and post‐acid petrophysical properties such as porosity, permeability, pore size distribution, and contact angle are measured for each sample along with the capillary rise profile. The latter is tracked by applying image analysis on video recording. The rock mineralogy significantly affects the acidic fluid intrusion into the rock samples. Calcite dissolution is the main reaction that results in the opening of the pore space. This is more prominent in all the carbonate samples where a higher proportion of calcite minerals is present. A higher capillary rise is consistently observed compared to the neutral fluid along with an increase in porosity and the mean pore size. The contact angle also undergoes changes making the carbonate matrix from oil‐wet to neutral‐wet. Coupling capillary interactions with fluid reactivity is often neglected in fluid transport phenomena. This study offers new insights into the relative importance of reactivity at the timescale of spontaneous imbibition. This is important in understanding dissolution and precipitation processes during capillary flow.

R. Newton, D. Perkins

Claudia Di Biagio, Jean-François Doussin, Mathieu Cazaunau et al.

Abstract Advancing knowledge of the mineralogical composition of dust is key for understanding and predicting its climate and environmental impacts. The variability of dust mineralogy from one source to another and its evolution during atmospheric transport is not measured at large scale. In this study we use laboratory measurements to demonstrate that the extinction signature of suspended dust aerosols in the 740 − 1250 cm−1 atmospheric window can be used to derive dust mineralogy in terms of the main infrared − active minerals, namely quartz, clays, feldspars and calcite. Various spectral signatures in dust extinction enable to distinguish between multiple global sources with changing composition, whereas modifications of the dust extinction spectra with time inform on size − dependent particles mineralogy changes during transport. The present study confirms that spectral and hyperspectral infrared remote sensing observations offer great potential for elucidating the size − segregated mineralogy of airborne dust at regional and global scales.

شهاب زنگنه, ملیحه عباس زاده, رضا قوامی ریابی et al.

در پروژه‌های اکتشافی، شناسایی ناهنجاری‌های ژئوشیمیایی در مناطق مختلف ممکن است تحت تاثیر فرآیندهای زمین‌شناسی، پیچیده‌گی‌های خاصی پیدا کنند. برای حل این ابهامات باید از روش‌های مختلف، برای درک صحیحی از اطلاعات موجود، استفاده شود. در این تحقیق با بیان مفهوم خوشه‌بندی سلسله مراتبی جهت شناسایی عناصر مرتبط با کانی‌سازی، تکینگی و نحوه ترسیم نقشه‌های تکینگی در قالب مدل‌های مولتی‌فراکتال و روش ماشین بردار پشتیبان، نواحی ناهنجار که احتمال کانی‌سازی در آن وجود دارد از مناطق زمینه تفکیک می‌شود. در ابتدا با روش خوشه‌بندی سلسله مراتبی و با استفاده از روش وارد، در خوشه‌های ایجاد شده، دو عنصر طلا و مس به عنوان عناصر مرتبط با کانی‌سازی شناسایی شدند. برای محاسبه شاخص تکینگی این دو عنصر، در هر نقطه از روش مبتنی بر پنجره و رابطه توانی عیار- مساحت استفاده شد. در نهایت با تفکیک مقادیر شاخص تکینگی به دو بخش آموزش و آزمایش و با کمک روش SVM فرآیند طبقه‌بندی و تخمین مقادیر شاخص تکینگی جهت شناسایی مناطق آنومال برای مناطق مجهول انجام پذیرفت. مطالعه موردی بر روی داده‌های مربوط به نمونه‌های سطحی خاک در محدوده کانسار مس پورفیری غنی از طلای دالی به مساحت 900×800 متر مربع واقع در کمربند ماگمایی ارومیه- دختر انجام شده است. نتایج حاصل از روش ترکیبی استفاده شده در این پژوهش با مطالعات قبلی مطابقت خوبی را نشان می‌دهد. در نتیجه استفاده از این روش‌های ترکیبی معرفی شده می‌تواند راهنمای مناسبی در جهت تولید نقشه-های ژئوشیمیایی در مناطق ناشناخته گردد.

H. Lorenz, J.-E. Rosberg, C. Juhlin et al.

<p>The Collisional Orogeny in the Scandinavian Caledonides (COSC) scientific drilling project aims to characterise the structure and orogenic processes involved in a major collisional mountain belt by multidisciplinary geoscientific research. Located in western central Sweden, the project has drilled two fully cored deep boreholes into the bedrock of the deeply eroded Early Paleozoic Caledonide Orogen. COSC-1 (2014) drilled a subduction-related allochthon and the associated thrust zone. COSC-2 (2020, this paper) extends this section deeper through the underlying nappes (Lower Allochthon), the main Caledonian décollement, and the upper kilometre of basement rocks. COSC-2 targets include the characterisation of orogen-scale detachments, the impact of orogenesis on the basement below the detachment, and the Early Paleozoic palaeoenvironment on the outer margin of palaeocontinent Baltica. This is complemented by research on heat flow, groundwater flow, and the characterisation of the microbial community in the present hard rock environment of the relict mountain belt. COSC-2 successfully, and within budget, recovered a continuous drill core to 2276 m depth. The retrieved geological section is partially different from the expected geological section with respect to the depth to the main décollement and the expected rock types. Although the intensity of synsedime<span id="page44"/>ntary deformation in the rocks in the upper part of the drill core might impede the analysis of the Early Paleozoic palaeoenvironment, the superb quality of the drill core and the borehole will facilitate research on the remaining targets and beyond. Protocols for sampling in the hard rock environment and subsequent sample preservation were established for geomicrobiological research and rock mechanical testing. For the former, a sparse sample series along the entire drill core was taken, while the target of the latter was the décollement. COSC-2 was surveyed by a comprehensive post-drilling downhole logging campaign and a combined borehole/land seismic survey in autumn 2021. This paper provides an overview of the COSC-2 (International Continental Scientific Drilling Project – ICDP 5054_2_A and 5054_2_B boreholes) operations and preliminary results. It will be complemented by a detailed operational report and data publication.</p>

G. Suresh, V. Ramasamy, V. Meenakshisundaram et al.

Mu Ramkumar, R. Nagarajan, M. Santosh

Sedimentary sequences preserve the records of changes in major controls of sedimentation namely, tectonics, climate, relative sea level and sediment production and preservation. The potential to characterize these changes in spatial and temporal scales has led to the development of the branch of chemostratigraphy. Chemostratigraphic study of sedimentary sequences commenced from recognizing identical/contrasting geochemical features across major geochronological boundaries, and evolved into one of the essential tools in exploration, characterization, and well development strategies. Chemostratigraphy incorporates applications on continuous, real-time geochemical mapping and direction of lateral drilling, and machine learning, among others. As the sedimentary systems operate on a variety of temporal scales that range from few hours (tidal cycles) to few tens of millions of years, within which many perturbations such as catastrophic and diagenetic events take place, that lead to unique geochemical signature which can be correlated at appropriate spatial and temporal scales. The application of chemostratigraphic technique in hydrocarbon exploration and reservoir characterization has gained momentum in recent years, particularly with the advent of developments in analytical instrumentation. This has also led to the integration of a variety of data from field sedimentary structures, mineralogy, major, trace and isotopic chemical compositions of whole rock, selected components of rocks, organic and inorganic components of oil and gas, etc., for reservoir characterization more accurately than ever. The geochemical fingerprinting of oil and gas reservoir components plays a major role in the identification of source rocks, discrimination of oil families, characterization of reservoir, source, and seal segments in petroleum systems. Future trends indicate the relevance and growing applications of machine learning techniques, artificial intelligence in real-time assessment, monitoring and planning of hydrocarbon exploration and production.

Fares M. Howari, Manish Sharma, Cijo M. Xavier et al.

In the present research, we carried out detailed chronological and compositional analyses along with detailed spectral analysis of three unnamed craters on the surface of Mars. Knowledge on chronology/age analysis and compositional analysis of Mars’ surface is essential for future manned and unmanned missions. The study area is near the landing site of previous landed missions, which could be used for future landing. The area is interesting to be studied because of its high elevation in the northeastern side and low elevation in the southern side, consisting of three major geological boundaries, i.e., Hesperian, Noachian, and Amazonian, which are further subdivided into fourteen units. Chronological investigations were carried out using the active machine learning approach and Craterstats 2.0 software, which revealed the age plot of 3.09 ± 0.04 Ga for Amazonian, 3.63 ± 0.0 Ga for Hesperian, and 3.73 ± 0.0 Ga for Noachian geological units, stating that N(1) craters’ density corresponds to the early Amazonian, early Hesperian, and late Noachian/early Hesperian periods according to the established crater density boundaries, respectively. Compact Reconnaissance Imaging Spectrometer for Mars (CRISM)-derived browse products are used for the compositional study of the surface characteristics of Mars. A spectral investigation was performed on an unnamed crater belonging to the Amazonian period, which showed to be majorly composed of oxides as the primary mineral, indicating the spectra of hematite, boehmite, and akaganeite. A Hesperian unit-unnamed crater shows the signature of monohydrated sulfates, melilite, illite, and kaolinite minerals in the region. For the unnamed crater 3, which belongs to the Noachian period, it has diagnostic absorptions of clay minerals in their extracted spectra, indicating the sign of long-term water–rock interactions in the period. Derived chronology results and compositional studies of craters help in better understanding the geological formation units of Mars’ surface.

Martinez, Isabelle, Shilobreeva, Svetlana, Alt, Jeffrey et al.

The contents and isotope compositions of water and carbon, including total, reduced, and inorganic (carbonate) C, were studied in 170 My altered oceanic basalts from Ocean Drilling Program Hole 801C in the western Pacific Ocean. Reduced C contents of 0.12–0.29 wt% CO2 and $\delta ^{13}$C values of $-22.6$ to $-27.8‰$ occur throughout the basement section. High total C concentrations in the upper volcanic section (UVS), above 300 m sub-basement, are dominated by inorganic C, and concentrations of both decrease with depth, from 1.92 to 0.57 wt% CO2 and 1.76 wt% CO2 to 0.66 wt% CO2, respectively. The $\delta ^{13}$C of inorganic C in the UVS ($-$0.4 to ${+}1.5{‰}$) indicates precipitation of seawater dissolved inorganic carbon (DIC) through the intensive circulation of seawater. $\delta $D values of $-$59.8 to ${-}17.6{‰}$ in the UVS also result from seawater interaction. In contrast, total C contents in the lower volcanic section (LVS) are low (0.22–0.39 wt% CO2) and dominated by reduced C, resulting in negative $\delta ^{13}$C values for total C ($-$18.7 to ${-}23.5{‰}$). We propose that a proportion of this reduced C could have formed through abiotic reduction of magmatic CO2 at the ridge axis. The contents and $\delta ^{13}$C values of inorganic carbon in the LVS (0.05–0.09 wt% CO2 and $-$10.7 to ${-}9.5{‰}$, respectively) fall in the range characteristic of C in mid-ocean ridge basalt glasses, also suggesting a magmatic origin. $\delta $D values in the LVS (weighted average $= {-}69.3{‰}$) are consistent with magmatic water. Reduced C in the basalts may also have formed through microbial activity at low temperatures, as indicated by previous work showing negative $\delta ^{34}$S values in the basalts.Our results show: (1) that magmatic C can be stored in altered oceanic basalts both as reduced and inorganic C resulting from high-temperature processes at mid-ocean ridges; (2) that microbial activity may add reduced C to the basalts during low-temperature alteration on ridge flanks; and (3) that circulation of cold seawater in the uppermost few hundred meters of basement adds seawater DIC as carbonate to the basalts and filling fractures in the basement. We estimate the content of magmatic C stored in the altered basaltic crust to be 0.126 wt% CO2. Compared with previous estimates, this concentration probably represents an upper limit for magmatic C. This resultant magmatic C flux into the crust, ranging from $1.5\times 10^{12}$–$2\times 10^{12}$ molC${\cdot }$y$^{-1}$ is similar to the outgassing CO2 flux [${\sim }1.32\pm 0.8$–$2.0 \times 10^{12}$ molC${\cdot }$y$^{-1}$, Le Voyer et al., 2019 and Cartigny et al., 2018, respectively]. Further data are needed to better constrain the fraction of magmatic CO2 that does not escape the oceanic lithosphere but remains stored as reduced and inorganic carbon.

D. Blake, D. Vaniman, C. Achilles et al.

A principal goal of the Mars Science Laboratory (MSL) rover Curiosity is to identify and characterize past habitable environments on Mars. Determination of the mineralogical and chemical composition of Martian rocks and soils constrains their formation and alteration pathways, providing information on climate and habitability through time. The CheMin X-ray diffraction (XRD) and X-ray fluorescence (XRF) instrument on MSL will return accurate mineralogical identifications and quantitative phase abundances for scooped soil samples and drilled rock powders collected at Gale Crater during Curiosity’s 1-Mars-year nominal mission. The instrument has a Co X-ray source and a cooled charge-coupled device (CCD) detector arranged in transmission geometry with the sample. CheMin’s angular range of 5∘ to 50∘ 2θ with 13 that are contained in the sample. The CheMin XRD is equipped with internal chemical and mineralogical standards and 27 reusable sample cells with either Mylar® or Kapton® windows to accommodate acidic-to-basic environmental conditions. The CheMin flight model (FM) instrument will be calibrated utilizing analyses of common samples against a demonstration-model (DM) instrument and CheMin-like laboratory instruments. The samples include phyllosilicate and sulfate minerals that are expected at Gale crater on the basis of remote sensing observations.

V. Mironov, L. Kosolapova, S. Fomin

Raúl Roberto Poppiel, Marilusa Pinto Coelho Lacerda, Rodnei Rizzo et al.

Soil color and mineralogy are used as diagnostic criteria to distinguish different soil types. In the literature, 350–2500 nm spectra were successfully used to predict soil color and mineralogy, but these attributes currently are not mapped for most Brazilian soils. In this paper, we provided the first large-extent maps with 30 m resolution of soil color and mineralogy at three depth intervals for 850,000 km² of Midwest Brazil. We obtained soil 350–2500 nm spectra from 1397 sites of the Brazilian Soil Spectral Library at 0–20 cm, 20–60, and 60–100 cm depths. Spectra was used to derive Munsell hue, value, and chroma, and also second derivative spectra of the Kubelka–Munk function, where key spectral bands were identified and their amplitude measured for mineral quantification. Landsat composites of topsoil and vegetation reflectance, together with relief and climate data, were used as covariates to predict Munsell color and Fe–Al oxides, and 1:1 and 2:1 clay minerals of topsoil and subsoil. We used random forest for soil modeling and 10-fold cross-validation. Soil spectra and remote sensing data accurately mapped color and mineralogy at topsoil and subsoil in Midwest Brazil. Hematite showed high prediction accuracy (R² > 0.71), followed by Munsell value and hue. Satellite topsoil reflectance at blue spectral region was the most relevant predictor (25% global importance) for soil color and mineralogy. Our maps were consistent with pedological expert knowledge, legacy soil observations, and legacy soil class map of the study region.