Basic Igneous Rocks Research Articles

Ti- and Ba-rich phlogopitic micas in alkaline basic and upper mantle igneous rocks; stoichiometry, stability, and Fe valence estimation reassessed and rationalised

Ti- and Ba-rich tri-octahedral micas occur in fractionated basic igneous rocks, metasomatized mantle peridotites, metamorphosed pelites/carbonates, and hydrothermally altered mineral deposits. Electron microprobe analyses (EMP), with all iron reported as FeO, were widely used in the 1970/80s to interpret Ti and Ba substitution mechanisms, based on 22 O2– unit cell calculations, implying that cation vacancies occur in octahedral and/or intersheet sites. In 1996 EMP with chemical and physical analyses for ferric and total Fe, H2O, (OH), and element-specific Fe X-ray Absorption Spectroscopy (both K and L-edges) established valence states for Fe and Ti and cation site occupancies, that ∼50 % O replaces (OH) molecules, and that 24 anion cell formulae show the absence of cation vacancies. Cell formula calculation protocol for phlogopitic micas is refined here and results tested against the stoichiometric formula for vacancy-free phlogopite, XIIK2VIMg6IV[Si6Al2]O20(OH)4. Hypothetical sheet silicate compositions, calculated with fixed contents of vacancies linked to particular mixed-valence element substitutions, confirm that reliable unit cell formulae for natural mica solids require that each stoichiometric vacancy must be accounted for. If reliable estimates for ‘excess O’ (denoted WO2−) are assigned to EMP analyses, the proportion of the oxy-mica component in a mica solid solution can be defined. This approach is tested using published analyses for Ti- and Ba-rich biotites from fractionated basic and ultramafic volcanic igneous rocks (oxymica range 2.5–45 %; TiO2 up to 14 %; BaO up to 23 %), upper mantle peridotites (equivalent values 7–18 %; 6 %; 0.7 %), and metasomatised upper mantle (2–37 %; 9 %; 23 %). Enrichments of Ti and Ba in micas are clearly linked to the extra oxygen charge required to neutralise the more highly charged Ba2+ and Ti4+ replacing K+ and Mg2+.Substitution mechanisms involving Ba, Ti, and Fe3+ in ideal phlogopite involve coupled inter-site / inter-valence interactions so both site-ordering and valence-balance between the different cation sites must be accounted for. The cation exchange 2XIIK+ + 4VI(Mg2+ + Fe2+) + 4IVSi4+ ↔ XIIBa2+ + 3VITi4+ + 4(Altotal + Fe3+ + Crtotal)3+ is used here so that valence and site order can be considered together. Compositional variations show well-defined trends towards high-oxymica content and vacancy-free Ti and Ba mica end-members, rather than to oxy-free end-members with essential vacancies. Average compositions for different source rock micas are used to assess compositional trends; molecular WO2− values are refined by relating initial estimates directly to the wt.% TiO2 contents; and refined WO2− and stoichiometrically calculated Fe3+/Fetotal ratios ranging ∼0.1–0.5) are correlated with possible primary magmatic values.

Some lithogeochemical and isotope-geochemical features of clay rocks and hiatuses in the Riphean stratotype

Research subject. Clay rocks of the Lower, Middle, and Upper Riphean (respectively, the Burzyan, Yurmatau, and Karatau groups) of the Western slope of the Southern Urals. Changes in their characteristic values of a number of ratios of oxides and some trace elements that are indicators of rock composition in provenances are considered, taking into account the breaks of different duration present in the Riphean stratotype. Methods. Calculation of t he average values of TiO2/Al2O3, Th/Sc, La/Co and (La/Yb)N, typical for shales, fine-grained clay siltstones, and mudstones of the main lithostratigraphic units of the Riphean stratotype (formation and, in some cases, subformation) and analysis of their changes taking into account the hiatuses known in the Riphean stratotype (Pre-Mashak/Pre-Zigalga, Pre- Zilmerdak, Pre-Minyar, Pred-Uk). Results. It was established that throughout the entire Riphean, regardless of breaks in sedimentation, presumably associated with certain transformations in the areas of erosion and sedimentation, a number of lithogeochemical characteristics of fine-grained clastic rocks of the Burzyan, Yurmatau, and Karatau groups (such as TiO2/Al2O3, Th/Sc, La/Co, and, to a significant extent, (La/Yb)N) practically did not experience significant changes. Conclusions. The data obtained give reason to think that there were no fundamental changes in the composition of the sources of fine-grained aluminosiliciclastics for the Riphean sedimentary sequences for more than 1 Ga, and contradict the rather active scenario of tectonic processes at the end of the Early Precambrian and the entire Late Precambrian. Conversely, the data on the values of tNd(DM) and eNd(t) in 37 samples of clay rocks of the Riphean stratotype nevertheless reflect a change in the composition of the rocks of the feeding provinces and, one way or another, fit into the outline of subglobal events established by conventional geological methods in the stratotype area of the Riphean. In accordance with them, in the Ai and Mashak times, an increase in the proportion of juvenile material took place in the areas of erosion. Apparently, the Pre-Zilmerdak hiatus also led to the appearance of a significant proportion of basic igneous rocks among the rocks of the provenances.

Petrography and Heavy Minerals as Tools for Provenance Identification of the Injana Sandstone (Upper Miocene), Al-Habbaniyah City, Anbar Governorate, Iraq

This study deals with the petrography and heavy mineral analysis of the Injana sandstone at Al-Habbaniyah City. Thirteen samples are collected from the Injana Formation. A petrographic study is achieved on ten samples while all samples are analyzed for heavy minerals. The petrographic analysis showed that the common components of the Injana sandstone are rock fragments, especially sedimentary fragments. Quartz grains (monocrystalline and polycrystalline) and feldspars (k-feldspar and plagioclase), bounded by matrix and carbonate cement. The suggested provenance for the Injana Formation is mainly sedimentary and igneous sources and the less dominant metamorphic source. These sandstones are considered to be mineralogically submature-immature and classified as litharenites. Heavy minerals analysis showed two sets of minerals including opaque and transparent minerals, the opaque minerals are significant components of the heavy mineral assemblages, then chlorite, epidotes, amphiboles, garnet, pyroxenes (ortho and clino), zircon, tourmaline, biotite, muscovite, rutile, and others. This assemblage implies that the dense minerals are typically found in basic igneous and metamorphic rocks, with less frequent occurrences in acidic igneous and reworked sediments. According to QLF and QmFLt classifications, the tectonic provenance of the Injana sandstone is described as recycled orogen. The MF-MT-GM classification showed that the sandstone of Injana is derived primarily from active continental margins. The result of maturity MI and ZTR revealed low values of maturity, the MI value ranges between 0.6 to 1.5 with an average of 0.9 and ZTR Maturity ranges between 0.7% and 9% with an average of 3.9%, these low values of maturity indicate sub-mature to immature sandstone.

Reservoir properties of effusive rocks of the Muradkhanli field (Azerbaijan)

The presence of oil accumulations in igneous rocks has been known for quite a long time. Geologists estimate that oil reserves in eruptive and weathered metamorphic rocks reach 1 % of the world’s proven oil reserves. At the Shaimskoye field (Western Siberia), oil is found in the weathered granites of the basement. Oil has been found in eruptive rocks in Texas (USA) fields, the most famous of which is the Litton Springs field. Oil is found in metamorphosed shales in the western part of the Los Angeles basin, the porosity of which is caused by the development of cracks in the roof of crystalline shales. Petroleum is extracted from serpentinites in Cuba. Basic igneous rocks contain petroleum at the Ferbro field in Mexico.At the Khukhrinsky gas field, which islocated at the north-western end of the Dnieper-Donets depression, the crystalline basement rocks are oil and gas bearing, from which commercial hydrocarbon inflows have been obtained. In the White Tiger field (Bach Ho), located on the southern shelf of Vietnam, commercial oil accumulations are also found in crystalline basement rocks.
 At the Muradkhanli field in Azerbaijan, the industrial accumulation of petroleum belongs to the igneous rocks of the Upper Cretaceous age. The natural oil and gas reservoir of the Muradkhanli field is confined to the erosion zone of the upper part of the section of these rocks.
 This work aims to determine the reservoir properties of the rocks of the Muradkhanli deposit, which belong to igneous rocks, in different ways.
 The method of estimation of final oil recovery of complex structure reservoirs was proposed for useful capacity and oil recovery of homogeneous media; different variants of the volumetric method were used for reservoirs with complex structures of pore space filling a complex and heterogeneous natural reservoir; values of hydrocarbon reserves of increased and secondary capacity were calculated for the study interval; distributions of oil reserves with right-sided asymmetry, where Mo<Me<X, were presented; it was determined that in effusive cores oil saturation and fluid filtration are caused by tectonic fracturing and cavernousness.
 Permeability varies in a wide range: 0.73·10–15—1.31·10–15 m2; the largest specific fraction of crack density is in the range 0—0.1 cm/cm2, the average value is 0.29 cm/cm2, with crack depth they decrease from 0.9 to 0.1 cm/cm2.
 The studies have shown that the natural reservoir of oil and gas in the Muradhanli field is associated with the erosion zone of the upper part of the igneous rock section.

Petrographic composition and material sources of Upper Paleozoic rough-clastic rocks in Western Taimyr

Research subject. Gravelites and conglomerates of the Upper Carboniferous and Permian of Western Taimyr. Aim. To reveal features of the petrographic composition of coarse clastic rocks and, on this basis, to clarify the ideas about the composition and position of the feeding province of the western part of the Taimyr sedimentary basin in the Late Paleozoic. Materials and methods. The analysis of materials collected during a layer-by-layer study of sections and microscopic description of 47 large transparent sections with the count of psephitic (more than 2 mm) fragments of quartzites, felsic and basic igneous, metamorphic and sedimentary rocks was performed. The revealed features of the petrographic composition of psephytoliths, in combination with a generalization of previously published geodynamic and paleogeographic reconstructions, were used to refine the model of the geological development of the Taimyr fold-thrust belt and adjacent areas in the Late Paleozoic. Results. It was established that the sections contain polymictic lithoclastic (83%) and petroclastic (15%) psephytoliths, with occasional inclusions of oligomictic essentially quartz varieties (2%). Minor changes in the composition of clasts over time indicate the existence of a single source of clastic material during the entire Late Paleozoic, which formed the sections of Western Taimyr. It was shown that the maturity of psephytolites increases from the southwest to the northwest and northeast. Numerous fragments of phtanites and lydites with remains of radiolarians of the Middle Devonian – early Early Carboniferous were identified, analogs of which are present in the Lemva zone of the Urals and in the basement of Western Siberia. Conclusions. The material forming the coarse clastic rocks of Western Taimyr was transported by the river for 600–1000 km from the folded structures of the “West Siberian land” located in the southwest (in modern coordinates), which formed in the Visean–Serpukhovian ages of the Early Carboniferous during the collision of the East - European, Kazakhstan and Siberian continental blocks.

Uranium isotopes as tracers of serpentinite weathering

The aqueous alteration of mantle rocks is considered to play a key role in Earth's global biogeochemical cycling. Uranium enrichment in fluid-altered mantle rocks is a common feature that may reflect redox state or fluid source, but it remains unclear when, why, and how uranium is mobilized within these systems. In this study we use uranium (U) isotopes (234U/238U and 238U/235U ratios) to deduce the timing, mobilization processes, and fluid sources responsible for weathering of subaerial and submarine serpentinites. We find that complex post-formation weathering processes continue to perturb serpentinite U isotope compositions and U concentrations long after initial serpentinization. Enriched 234U/238U ratios in dredged seafloor serpentinites require recent (<1.5 Myr) uptake of U, likely from derived from chemically evolved seawater that has circulated through igneous basement rocks. In contrast, depleted and variable 234U/238U ratios in a terrestrial serpentinite across <30 cm spatial scales from the Wadi Fins outcrop in the Samail Ophiolite, Oman, indicate alpha recoil effects, with differences in these ratios reflecting different grain sizes or shapes of U-hosting minerals in different weathering zones. Both seafloor and Wadi Fins serpentinites have 238U/235U ratios significantly different from seawater and mid-ocean ridge basalts, reflecting different initial protolith composition and/or overprinting of 238U/235U ratios during weathering. Using 238U/235U and U concentrations we calculate the isotopic composition of evolved fluids weathering the serpentinites at both localities. We also use 234U/238U and models of alpha recoil to determine the grain sizes of minerals hosting U from samples at Wadi Fins. Our results suggest that U isotopic compositions and concentrations are sensitive to post-serpentinization weathering processes in subaerial and submarine environments. The U isotopic composition of abyssal serpentinites is set by seawater that has chemically evolved during flow through basement rocks, questioning the utility of weathered serpentinites as an archive of paleo-seawater U isotope compositions, as well as other fluid-mobile elements modified during crustal fluid flow.

Sources of Material for Surface Bottom Sediments in Some Regions of the Nordic Seas (According to Geochemical Data)

The mineral, bulk chemical (main rock-forming oxides) composition and systematics of rare-earth elements, Sc, Cr, Zr and Th of surface bottom sediments taken in a number of cruises of the R/V Akademik Mstislav Keldysh in the Nordic Seas (Mona, Knipovich, Kolbeinsey and Aegir ridges, the basins of the Norwegian and Greenland seas, the continental slope of Svalbard, the western continental margin of the Barents Sea, etc.) are considered to determine the sources of fine-grained material of bottom sediments. If for coastal sediments the primary influence of terrigenous drift is obvious, then seaward sediments are affected by “relatively war-mer” Atlantic waters, leading to their dilution with calcium carbonate, the main producers of which are planktonic foraminifers. It is concluded that the source of fine-grained aluminosiliciclastics for most of the studied samples were both acidic and basic igneous rocks (volcanic rocks of Iceland) in different proportions.

Petrogenesis, tectonic setting and geodynamic implications of keziergayin granites in the kelan basin (Chinese Altai): constraints from geochemistry, zircon U-Pb geochronology and Nd‒Hf‒Pb‒O isotopes

The Chinese Altai is characterized by abundant granitoids, which not only are indicators of the interaction between crust and mantle but also provide critical constraints on the tectonic evolution of the orogen. This study presents zircon U‒Pb‒O isotopes, whole-rock major and trace element and Nd‒Hf‒Pb isotopes data for granite porphyries from the Keziergayin region in the Kelan Basin. The granite porphyries intrude in the Kangbutiebao Formation with zircon U‒Pb dating of 394 ± 3 Ma. They have the characteristics of subalkaline and metaluminous to weakly peraluminous and show geochemical affinity with I-type granite. The granite porphyry samples display negative εNd(t) (−1.9 to −1.4), positive εHf(t) (+4.3 to +11.4) values, with Nd–Hf decoupling; low Pb isotope compositions; δ18OV-SMOW (6.38‰–8.45‰) is less than 10‰, within the range of O isotopes of medium-basic igneous rocks. These geochemical signatures indicate that the granite porphyries originated from lower crust medium−basic igneous rocks extracted from the lithospheric mantle metasomatized by subducted melt. They are characterized by high SiO2 contents and Rb/Sr ratios; low CaO contents and K/Rb ratios, hinting that they were formed by highly evolved magmas, with fractionation crystallization of feldspar, apatite, garnet, allanite and/or monazite. The granite porphyries possess positive Rb, Th, U, Nd, Zr, Pb and light rare Earth elements (LREEs) anomalies with strong negative Ba, Nb, Ta, Sr, P, Ti and Eu anomalies, implying that their formation were related to an island arc. Combined with previous studies, it is suggested that the existence of the Early Devonian arc-basin system associated with subducting slab rollback in the Chinese Altai, which belongs to the Siberian active continental margin system.

Clay minerals study of the Kolosh Formation at selected sections from northern Iraq: Implications for provenance history

The mineralogical study using X-ray diffraction (XRD) supported by scanning electron microscopic (SEM) examination and energy-dispersive spectroscopy (EDS) on the claystone of the Kolosh Formation from northern Iraq was conducted to Shows the provenance history of rocks. Chlorite, montmorillonite, illite, palygorskite, and kaolinite were recorded in different amounts in the study area. The association of montmorillonite and chlorite in the claystone of the Kolosh Formation (Paleocene) refers to the marine environment. Chlorite and montmorillonite are the common minerals in the Kolosh Formation with less common of illite, kaolinite and palygorskite. These clay minerals are of authigenic, detrital and diagenetically origin, which are controlled mainly by the source rocks, paleoclimatic conditions and the burial diagenesis. The clay minerals assemblages refer to be derived mainly from Fe-Mg rich with minor Si-Al rich silicate minerals, which are very common in the ophiolites associated with the basic igneous rocks. These rocks composed the major lithological units in the Zagros Thrust Belt of NE Iraq.

Geochemistry and geochronology of basic igneous rocks in Bairin Right banner, southeastern inner Mongolia, China: Implications for the final closure of the Paleo—Asian Ocean along the Xar Moron suture zone

This paper reports the first discovery of basic igneous rocks in Bairin Right Banner in southeastern Inner Mongolia, China. To understand the genesis and tectonic evolution of these rocks, we have carried out geochronology and geochemistry research on them. The results show that LA-ICP-MS zircon U-Pb concordant mean ages of massive basalt, diabase, and pillow basalt are 272.0 ± 2.8 Ma, 261.5 ± 3.2 Ma, and 256.5 ± 2.5 Ma, respectively, suggesting their formation during the Late Permian. The massive basalt, diabase, and pillow basalt are tholeiitic with low Mg# values in the ranges of 46.2–66.8, 54.4–71.0, and 53.5–58.2, respectively. They have similar chondrite-normalized rare earth element (REE) patterns. The intensity of REE differentiation is similar to that of typical enriched mid-ocean ridge basalts (E-MORB). The pillow basalts are relatively enriched in Ba and U, while slightly depleted in Rb and Th, and show geochemical affinity to E-MORB. The massive basalts and diabases have the same primitive mantle-normalized patterns and are relatively enriched in Rb, Ba, and U, while depleted in Nb and Ta, similar to the typical island arc magmas. Our new findings indicate that the intra-oceanic subduction of the Paleo-Asian Oceanic slab was still ongoing during the late Permian in the Bairin Right Banner area and, combined with previous studies, it might have been closed during the Late Permian to Early Triassic along the Xar Moron suture zone.

MIDDLE MIOCENE VOLCANISM IN THE ČITAKLIJA LOCALITY OF VARDAR ZONE, NORTH MACEDONIA

This paper presents the results of the investigations of volcanic rocks of Middle Miocene age in the central parts of the Varadar zone for the first time. The volcanic rocks that appear in the Čitakliјa locality, according to their petrological and mineralogical characteristics, represent basic igneous rocks and they are transitional rocks between phonotephrites and high potassium shoshonites. The geochemical distribution of trace elements and elements from the group of rare earths (REE), as well as isotopes of 87Sr/86Sr (0.708348) and isotope values of 143Nd/144Nd (0.512319) indicate the fact that the magmatic sources of these rocks can be located in the border region between the upper mantle and the lower part of the continental crust.

Mineralogy of Recent Sediments of AL-Teeb River Basin East Missan Governorate Southeastern Iraq

The main aim of this research is to define the mineralogical composition of recent sediments deposited around the Al-Teeb river basin in eastern Missan, trying to determine the provenance or the source of these sediments. The study area represents the southeastern edge of the Mesopotamian Plain and is part of it. Quaternary deposits cover most of the area. It is clayey with old sea and river deposits and part of aeolian deposits. These sediments cover 95% of the study area, while the older rocks, which date back to the Tertiary (Late Miocene – Pliocene), exposed in the area east and northeast of the Al-Teeb area, made up hills which back to the undifferentiated Pliocene Mukdadiya and Bai-Hassan formations. The light components of these sediments consist mainly of quartz, feldspars (potash and plagioclase feldspar), sedimentary rock fragments (carbonate rock fragments, chert rock fragments, evaporates fragments), igneous rock fragments, and metamorphic rock fragments The heaviest minerals are opaque, amphiboles, pyroxenes, chlorite, epidotes, biotite, garnet, muscovite, zircon, kyanite, staurolite, and rutile. These sediments are typically formed by sedimentary rocks (single or many cycles), low and high-rank metamorphic rocks, acidic and basic igneous rocks, and pegmatite rocks. The high percentage of opaque heavy minerals in clastic sediment refers to unstable clastic sediments. The stability issue to the areas during the study shows that there are significant variances over the several places, indicating dissimilar sources and types of source rocks

KARAKTERISTIK MATERIAL KOMPOSIT BERBASIS BATUAN BASALT DAN DROSS AL

Basalt is one of the basic igneous rocks formed from the freezing process of magma on the earth's surface and has a very good grain size. This study aims to determine the characteristics of the composite basalt as initial data for the manufacture of brake linings. In this study, basalt was made into a composite with the composition of basalt and dross Al of 45:30%, 55:20%, 65:10% and polyester resin 25%. The material used has particle sizes of 100, 150, and 200 mesh. The materials were made by mixing for 5, 10, and 15 min. Then carried out the compaction process with a load of 2 tons with a holding time of 5 min. Next, the material was sintered at 150 oC for 2 h. The characteristics studied were compressive strength referring to ASTM D695-15 and Absorption referring to SNI 03-2105-2006. From the results of composite testing, the best characteristics were found in specimen 3, with a compressive strength value of 113.616 MPa and Absorption of 1.39%.

The Role of Heavy Minerals in Understanding the Provenance of Sandstone: An Example from the Upper Cretaceous Tanjero Formation, Surdash Region, Northeastern Iraq

The Tanjero Formation is the Upper Cretaceous (Campanian-Maastrichtian) crops out in northeastern Iraq at the High-Folded and Imbricate Zones. To study heavy minerals, twenty sandstone samples were obtained from selected sites of the Tanjero Formation exposed at the southwestern limb of the Surdash anticline in the northeast part of Sulaimanyia city. The analyzed data indicates that the most abundant heavy minerals are opaque, followed by pyroxene, epidote, amphibole, chlorite, rutile, and garnet. The significant abundance of unstable and metastable minerals in the heavy mineral suites shows their direct derivation from the adjacent main basic igneous and metamorphic source rocks, which are situated in the High-Folded and Imbricate Zones in the northern and northeastern parts of Iraq. The estimated zircon-tourmaline-rutile index reveals that the majority of the sandstone samples have less than 75% zircon-tourmaline-rutile index, indicating that the sediments are generally immature. Furthermore, the relationship between an ultra-stable and a meta-stable heavy mineral indicated the immaturity of the Tanjero Formation sandstone and its moderate stability, proving that these minerals cannot be transported over extremely long distances close to the source rocks area. The heavy mineral assemblage demonstrated that the studied area is distinguished by high tectonic activity. In addition, according to the MF- MT-GM ternary diagram, the analyzed sandstone samples lie within the active continental margins field, which is distinguished by a higher percentage of MF minerals than GM minerals generated from mafic magmatic source rocks.

Geochemical and mineralogical study of the fluvial deposits at Abul Khasib area, south east of Iraq

Nine sediment samples were collected from three sites at the banks (levees) of Sarraji, Hamdan and Abul khasib creeks branching from Shatt Al-Arab river, southeastern Basrah with depths of 0.5, 1.0 and 1.5m, respectively. Grain size distribution and statistical parameters revealed that the deposits are mainly composed of silt and clay with very small portion of sand, and have mud type texture. There is a tendency of increasing in silt percentage from Sarraji toward Abul Khasib area and decreasing in clay percentage with depth. Generally, the sediments are poorly sorted, coarse to strongly coarse skewed and platykurtic to very platykurtic deposited in quiet environment and low energy conditions. Chemical analysis showed that all samples have high concentration in SiO2 and CaO in comparison with Al2O3, Fe2O3, MgO, SO3, K2O and Na2O. These results are generally in agreement with the mineral composition. Mineralogically, the sediments understudy consists of quartz, feldspar, calcite, dolomite and gypsum. Clay minerals assemblages are: chlorite-montmorillonite mixed layers 37%, Illite 20%, Chlorite 18%, Kaolinite 14% and Palygorskite 11%. Increasing in Ch-Mont. percentage could be an evidence of high intensity of diagenetic alteration processes in depositional environment. The clay mineral assemblages proved that the recent sediments of the studied samples were derived from the basic igneous and metamorphic rocks, while acidic igneous and sedimentary rocks sources are less important. The deposition environment of these minerals may be characterized by an arid to semi-arid climate in the source area.

CLAYEY ROCKS OF THE UPPER PROTEROZOIC SUIROVO FORMATION, WESTERN SLOPE OF THE SOUTHERN URALS: SOME FEATURES OF GEOCHEMISTRY

The article presents the results of the analysis of some geochemical features of the clayey rocks of the Suirovo Formation (Bashkirian meganticlinorium, Southern Urals). It is shown that the Zr/Sc and Th/Sc ratios in mudstones, as well as a number of lithochemical modules, gives reason to believe that thin-grained aluminosilicoclastics of the first sedimentation cycle prevails in their composition. The distribution of the mudstone data points on the La/Sc — Th/Co and Cr/Th — Th/Sc diagrams indicates the presence of a noticeable part of the products of destruction of the basic igneous rocks. The same can be assumed on the basis of their inherent average values (La/Yb)N and Eu/Eu*. Localization of the mudstone data points on the (La/Yb)N — Eu/Eu* diagram with fields characterizing the composition of the fine-grained suspension of the estuarine parts of modern rivers of different categories suggests that the provenances of the Suirovo basin were composed of a diverse complex of rocks (sedimentary rocks, acidic and basic igneous and volcanic rocks), and the rivers that transported thin-grained aluminosilicoclastics were classified as large. On the Th — La — Sc diagram, the mudstone data points tend to the field of compositions typical of oceanic island arcs, which is consistent with their position on the (Fe2O3* + MgO) — Al2O3/SiO2 diagram.

Removal of atmospheric CO2 by engineered soils in infrastructure projects

The use of crushed basic igneous rock and crushed concrete for enhanced rock weathering and to facilitate pedogenic carbonate precipitation provides a promising method of carbon sequestration. However, many of the controls on precipitation and subsequent effects on soil properties remain poorly understood. In this study, engineered soil plots, with different ratios of concrete or dolerite combined with sand, have been used to investigate relationships between sequestered inorganic carbon and geotechnical properties, over a two-year period. Cone penetration tests with porewater pressure measurements (CPTu) were conducted to determine changes in tip resistance and pore pressure. C and O isotope analysis was carried out to confirm the pedogenic origin of carbonate minerals. TIC analysis shows greater precipitation of pedogenic carbonate in plots containing concrete than those with dolerite, with the highest sequestration values of plots containing each material being equivalent to 33.7 t C ha−1 yr−1 and 17.5 t C ha−1 yr−1, respectively, calculated from extrapolation of results derived from the TIC analysis. TIC content showed reduction or remained unchanged for the top 0.1 m of soil; at a depth of 0.2 m however, for dolerite plots, a pattern of seasonal accumulation and loss of TIC emerged. CPTu tip resistance measurements showed that the presence of carbonates had no observable effect on penetration resistance, and in the case of porewater pressure measurements, carbonate precipitation does not change the permeability of the substrate, and so does not affect drainage. The results of this study indicate that both the addition of dolerite and concrete serve to enhance CO2 removal in soils, that soil temperature appears to be a control on TIC precipitation, and that mineral carbonation in constructed soils does not lead to reduced drainage or an increased risk of flooding.

Igneability feature: an effective, easy and low-cost way to identify basic igneous rocks using wireline well logs in open hole wells

The correct identification of igneous rocks is of fundamental importance during drilling and to the quality of the initial assessment of their role in the petroleum systems. These rocks show characteristics in geophysical well logs that are distinct from those of sedimentary rocks. After calibrating with laboratory data, we propose a method to identify and characterize igneous rocks using basic geophysical logs. This method consists of a crossover between bulk density and photoelectric factor logs to identify basic igneous rocks in sedimentary sections, named "igneability feature". This log feature consists in using the bulk density log on the scale 2.0 to 3.0 g/cm³ in the same track as the photoelectric factor log on the inverted scale, from 12 to 2 b/e. Then, when the density log is to the right of the photoelectric factor, it denotes the presence of basic igneous rocks.Acid igneous rocks were also studied and characterized by a complementary method, which consists in a crossover between the gamma ray log and a factor calculated from the bulk density and photoelectric factor log curves. Thus, this method covers most of the varieties of igneous rock found in the Brazilian basins, such as Santos, Parnaíba and Paraná.

Authigenic Green Mica in Interflow Horizons within Late Cretaceous Deccan Volcanic Province, India and Its Genetic Implications

Green authigenic mica, i.e., celadonite, is commonly associated with submarine alteration of basic igneous rock. However, very few studies have reported the formation of celadonite under nonmarine conditions. An integrated study involving field investigation, petrography, mineralogy, and mineral chemistry highlighted the origin of celadonite in two clay-rich horizons (green boles) of the Late Cretaceous Deccan volcanic province. Within the Salher green bole, the celadonite occurred as the dissolution and alteration of plagioclase, volcanic glass, and pore-filling cement. In the case of the Pune green bole, the celadonite was formed by the alteration of plagioclase, pyroxene, and precipitation as film within intergranular pores, along with zeolite. The celadonite in the Salher green bole exhibited slightly lower K2O and Fe2O3 and higher Al2O3 than in the Pune. The mineral chemistry of the former showed a composition closer to ferro-aluminoceladonite. Although the mineral chemistry of celadonite overlaps with glauconite, the distinct 10 Å and 15 Å reflections in XRD, euhedral lath and honeycomb morphology under SEM, and characteristic absorption bands in VNIR spectroscopy (0.4–2.5 µm) and FTIR spectroscopy (400–4000 cm−1) identified celadonite and Fe-smectite within green boles. The green boles were formed either by the alteration of a volcaniclastic deposit in local pools of water or by the in situ alteration of the fragmentary flow top. The present study is significant due to the occurrence of celadonite in a nonmarine environment, as it otherwise forms under submarine conditions.

New insights on the Alboran Sea basin extension and continental collision from magnetic anomalies related to magmatism (western Mediterranean)

In the Alboran Sea there are a few well exposed Neogene and Quaternary volcanic zones, often geographic highs, that are generally associated with magnetic anomalies. In this paper, we present a characterization of these magnetic anomalies based on a recent and accurate magnetic data compilation for the Abloran Sea area. The anomalies reveal the distribution of magmatism and shed light into the discussion about the origin and evolution of the westernmost Mediterranean. One of the most relevant magnetic anomalies is the Nador dipole, which extends from the Gourougou volcano to the Chafarinas Islands, and is related to an E-W crustal scale intrusion. However, the main NE-SW elongated continuous dipoles of the central Alboran Sea are not related to any surface structure, but they are parallel to the Alboran Ridge, which is the main volcanic high in the Alboran Sea, and are located to the north of it. These anomalies extend discontinuously eastward along the NW-SE dipoles located along the Yusuf fault zone. The results of our 2D magnetic forward modeling suggest that the causative bodies of these main magnetic dipoles are deep igneous bodies. According to the tectonic evolution of the region, and the high magnetic susceptibility values obtained, these igneous bodies probably are made of a basic igneous rocks. Their emplacement may represent the westward tip of the rift axis of the AlKaPeCa Domain, which is related to the Oligocene-Miocene NW-SE extension, and associated with the southern slab retreat stage and oceanic spreading of the Algerian basin. Afterwards, these bodies were displaced toward the west, together with the Alboran Domain, and affected by the STEP fault located at its southern limit. Since the Late Miocene, the north Alboran Ridge elongated intrusions acted as a backstop that conditioned the folding and uplift of the Alboran Ridge in a tectonic indentation setting. In this setting, the STEP fault is deformed and the eastern part of the bodies were segmented along the Yusuf transtensional fault system. Simultaneously, the E-W crustal body related to the Nador magnetic dipole was emplaced, possibly evidencing a slab tearing process. The deep seated basic igneous bodies constitute main crustal heterogeneities that reveal and drive the Alboran Sea tectonic inversion.