Aluminum Saturation Research Articles

Petrogenetic and tectonic interpretation of strongly peraluminous granitic rocks and their significance in the Archean rock record

Abstract Strongly peraluminous granitic rocks (SPG), defined by an aluminum saturation index ≥1.1, become abundant in the rock record in the Neoarchean. This study identifies three different varieties of Neoarchean SPG in the Archean Wyoming Province, U.S.A. These include calcic SPG, represented by the Webb Canyon Gneiss and Bitch Creek Gneiss of the Teton Range; calc-alkalic to alkali-calcic suites composed entirely of SPG, including the Rocky Ridge garnet granite gneiss of the northern Laramie Mountains and the Bear Mountain granite in the Black Hills; and calc-alkalic to alkali-calcic suites that include both weakly and strongly peraluminous granitic rocks, such as the Mount Owen batholith, Wyoming batholith, and Bears Ears granite. Although the petrogenesis of all the SPG suites involves partial melting of crustal sources, the composition of those sources, the melting conditions, and the tectonic settings vary. The calcic suites originate by dehydration melting or water excess melting of hornblende-plagioclase rocks at relatively high temperature. The suites composed entirely of SPG formed by partial melting of metasedimentary rocks by reactions involving muscovite at lower temperatures. Suites with both weakly and strongly peraluminous granite may form by partial melting of metasedimentary rocks by reactions involving biotite or by assimilation of aluminous melts of felsic crust by differentiated calc-alkalic magma. Most of the Wyoming SPG appear to have formed in collisional orogens, but SPG of the Wyoming batholith and Bears Ears granite are associated with continental arc magmatism. The appearance of SPG in the Neoarchean rock record marks the time when subduction enabled the formation of strong, thick, increasingly felsic continental crust, which in turn allowed the development of a mature, clastic sedimentary cover. Lateral movement of crustal blocks led to collisional orogeny, SPG magma genesis, and the formation of the first supercontinents.

Edaphic attributes in pedoforms of gullies, in the Southeast region of Brazil

Water erosion acts as the main form of soil degradation, promoting the release of particles that associated with factors such as climate, relief, soil vegetation and use and occupation favor this process. This study aimed to evaluate whether gullies are more likely to be present in a specific type of landform and how physical and chemical soil characteristics vary between the internal and external environments of concave and convex gullies. The study was performed in the Cachimbal River sub-basin, Pinheiral (RJ). Gullies were mapped and the quantitative and qualitative evaluations (occurrence in concave or convex surface). For each type of landform, one gully was selected. Soil samples (disturbed and undisturbed) were collected from the internal and external surfaces of each gully at a depth of 0-10 cm and soil chemical and physical characteristics were determined. More gullies were present in convex landforms and differences in soil characteristics were observed between the internal and external gully surfaces, but not between different landforms. Ca+2, S value, H+Al, T value, Mg+2, TOC and K+ were associated with the external surface, and P, Al+3, aluminum saturation, V%, and pH with the internal surface. Natural and total clay content, and soil and particle density were the physical characteristics associated with the external surface, and total and fine sand content, porosity, degree of flocculation, and silt content with the internal surface.

Formation age and geological environment of monzonitic granite from Qingshanpu pluton on the eastern margin of Longshou, Gansu

Zircon U–Pb dating, geochemistry, and Sr–Nd–Hf isotope data are reported for monzonite from the Qingshanpu pluton on the eastern margin of Longshoushan. The zircon LA-ICP-MS U–Pb age data showed that the emplacement age of the monzonite is 442.6 ± 4.8 Ma. The rocks are characterized by high SiO2 contents (73.15%–73.85%), high K2O contents (3.67%–3.99%), and low P2O5 contents (0.042%–0.049%). The aluminum saturation index was 1.03–1.05, and the molecular number of standard corundum was 0.58%–0.77%. Rocks are enriched in Rb, Sr, U, K, and Pb and depleted in Nb, Ti, Zr, P, and Eu, thereby indicating that they are weakly peraluminous I-type granites. The monzonite in the Qingshanpu pluton had lower ISr values, which ranged from 0.70850 to 0.70904, and the εNd(t) values ranged from -8.54 to -6.49. The εHf(t) values ranged from -9.75 to 0.42, and the two-stage model age TC DM ranged from 1406 to 2043 Ma. This study concluded that the North Qilian subducted beneath the Alxa Plate at the end of the Early Paleozoic, causing elastic collision and eventually leading to closure. During elastic collision, several parts of the orogenic belt collapsed and were dismantled. The remelted ancient crust mixed with a small amount of mantle material during its ascent and finally formed the Qingshanbao pluton.

Technology and equipment for isolated aluminum melt overflow from a vacuum transport ladle with using the siphon

The work was performed at the Sayanogorsk aluminum plant UC RUSAL in the technological scheme from an aluminum cell to an alloying furnace. The article presents comparative results of studies of the dynamics of saturation of aluminum with hydrogen when using a vacuum transport ladle with a closed (siphon) cast metal overflow and the existing technology of overflow. The basic design of a vacuum transport ladle with a removable siphon is presented. It is shown that one of the main sources of saturation of aluminum melt with hydrogen is its interaction with air moisture during open overflows of metal during its movement from the cell to the alloying furnace. During the study, it was found that pouring aluminum from the cell using traditional technology increases the hydrogen content by an average of 0.045 cm3/100 g Al, and pouring aluminum from the cell with an experimental ladle with a siphon increases the concentration of hydrogen in the metal by an average of 0.029 cm3/100 g Al. It was found that when pouring aluminum from the ladle into the alloying furnace using traditional technology, the hydrogen content increases from 0.220 cm3/100 g Al to 0.297 cm3/100 g Al, and when using a vacuum transport ladle with a closed (siphon) overflow, the hydrogen content decreases from 0.189 cm3/100 g Al to 0.161 cm3/100 g Al. It is shown that an additional advantage of pouring aluminum melt with an experimental vacuum transport ladle with a closed (siphon) overflow is to reduce the amount of dross removed from the metal surface, as well as to reduce metal losses due to oxidation of the melt. The specific dross formation according to the existing overflow technology was 1,962 kg/t Al, and when using an experimental vacuum pump with a closed (siphon) overflow, the specific formation of dross was 1,204 kg/t Al.The work was performed using the results of research conducted during the implementation of project 14.578.21.0193 from October 3 for the period 2016–2018. “Development of theoretical and technological solutions for reducing hydrogen in aluminum and low-alloy aluminum alloys” in the framework of the Federal target program “Research and development in priority areas of development of the scientific and technological complex of Russia for 2014–2020” with financial support from the Ministry of education and science of Russia.

Tracking and Evaluating the Concentrations of Natural Radioactivity According to Chemical Composition in the Precambrian and Mesozoic Granitic Rocks in the Jangsu-gun Area, Central Southwestern South Korea

The Jangsu-gun area in the central Southwestern South Korea consists of a well-preserved Middle Paleoproterozoic gneissic basement, as well as the Late Triassic and Early Jurassic granitic rocks. Here, we present the detailed zircon U-Pb age data and whole-rock chemical compositions, including radioactive elements (e.g., U and Th) and activity concentrations of 226Ra, 232Th and 40K for the Middle Paleoproterozoic gneisses, and Late Triassic and Early Jurassic granitic rocks of the Jangsu-gun area. The Middle Paleoproterozoic gneissic basement, and the Late Triassic and Early Jurassic granitic rocks have ages of ca. 1988 Ma and 1824 Ma, 230 Ma and 187–189 Ma, respectively. Geochemically, the Middle Paleoproterozoic orthogneiss, Late Triassic granites and Early Jurassic granitic rocks show typical arc-related metaluminous to weakly peraluminous fractionated granite features with ASI (aluminum saturation index) values of 0.92 to 1.40. The mean values of U (ppm) and Th (ppm) of the Middle Paleoproterozoic orthogneisses (6.4 and 20.5, respectively), Late Triassic granites (1.5 and 10.9), and Early Jurassic granites (3.5 and 16.5) were similar to those (5 and 15) of the granitic rocks in the Earth’s crust. The mean 226Ra (Bq/kg), 232Th (Bq/kg), and 40K (Bq/kg) activity concentrations and radioactivity concentration index (RCI) are 62, 71, 1,214 and 0.96 for the Middle Paleoproterozoic orthogneisses; 16, 39, 1,614 and 0.78 for the Late Triassic granites; and 56, 70, 1031 and 0.88 for the Early Jurassic granitic rocks, respectively. The U, Th, 226Ra, 232Th, 40K, and RCI of the Middle Paleoproterozoic biotite paragneisses are similar to those of the Middle Paleoproterozoic orthogneisses. The trend of 226Ra, 232Th, and 40K activity concentrations, and the composition of U and Th from the Precambrian and Mesozoic rocks in the Jangsu-gun area indicates that monazite is the main accessory mineral controlling the concentration of natural radioactivity. Based on a detailed examination of the natural radioactivity in the rocks of the Jangsu-gun area, the Middle Paleoproterozoic orthogneisses and paragneisses, and Late Triassic and Early Jurassic granitic rocks show average high mean RCI values of 0.88−0.96, such that 32% of the rocks exceeded the recommended value of one in the guidelines for the RCI in South Korea. Especially, the RCI is closely related to the radon levels in the rocks. As a result, the Jangsu-gun area in South Korea is a relatively high radiological risk area, which exhibits higher indoor radon levels in the residences, compared with residences in the other areas in South Korea.

Soil Chemical attributes under different management systems in Cerrado-Amazon ecotone

The Cerrado-Amazonas ecotone occupies 4.85% of the Brazilian territory, with almost 60% of its area deforested. Inadequate soil management practices cause changes in the physical, chemical and biological soil attributes. This study aimed to characterize soil chemistry in different management systems, identifying its efficiency. Ten areas were divided into two soil classes (Ultisol and Entisol quartzipsamment), each comprising a management system (1 - silvopastoral with 30% shade (SP30), 2 - silvopastoral with 60% shade (SP60), 3 - secondary forest, 4 - native forest, 5 – pasture conventional (CP)). The samples were collected at depths of 0-10, 10-20 and 20-40 cm. The chemical attributes of the soil analyzed were pH, P, K +, Ca2 +, Mg2 +, H + Al3 +, Al3 +, sum of bases (SB), effective cation exchange capacity (CEC), CEC at pH 7, saturation base (V%) and aluminum saturation (m%). The data were submitted to principal component analysis and analysis of variance and Tukey's test (p <0.05). There were minor changes in the attributes analyzed in the Entisol management systems, comparing the other systems with the reference system (native forest); however, SP30 was more suitable, as it increased the pH and the values of essential cations in the soil. In Ultisol, the SP60 and CP systems showed higher averages in the studied attributes, it is inferred that these systems have similar efficiency in land use, positioning them as the best systems studied in this soil class.

Land-Use System and Forest Floor Explain Prokaryotic Metacommunity Structuring and Spatial Turnover in Amazonian Forest-to-Pasture Conversion Areas.

Advancing extensive cattle production is a major threat to biodiversity conservation in Amazonia. The dominant vegetation cover has a drastic impact on soil microbial communities, affecting their composition, structure, and ecological services. Herein, we explored relationships between land-use, soil types, and forest floor compartments on the prokaryotic metacommunity structuring in Western Amazonia. Soil samples were taken in sites under high anthropogenic pressure and distributed along a ±800 km gradient. Additionally, the litter and a root layer, characteristic of the forest environment, were sampled. DNA was extracted, and metacommunity composition and structure were assessed through 16S rRNA gene sequencing. Prokaryotic metacommunities in the bulk soil were strongly affected by pH, base and aluminum saturation, Ca + Mg concentration, the sum of bases, and silt percentage, due to land-use management and natural differences among the soil types. Higher alpha, beta, and gamma diversities were observed in sites with higher soil pH and fertility, such as pasture soils or fertile soils of the state of Acre. When taking litter and root layer communities into account, the beta diversity was significantly higher in the forest floor than in pasture bulk soil for all study regions. Our results show that the forest floor’s prokaryotic metacommunity performs a spatial turnover hitherto underestimated to the regional scale of diversity.

COMPARATIVE ASSESSMENT OF TROPICAL RAINFOREST SOILS FORMED FROM DIFFERENT GEOLOGIC FORMATIONS IN SOUTHEASTERN NIGERIA

Data on the nature, properties and potentials of soils is grossly inadequate in the rainforest belt of southeastern Nigeria. As such, policymakers and other land users have tended to subscribe to unduly generalized ideas about the soils of the region. This has led to improper land use planning and aggravated land degradation. This necessitated the need for the comparative evaluation of the nature and potentials of the soils of the region to determine their degree of variability. Profile pits were dug in four towns underlain by different geologic formations: Umungwa (Benin Formation), Umuawa Ogii (Nsukka Formation), Ikpem (Igbaku Sandstones) and Amuro (Imo Clay Shales). The soils were characterized and classified using the World Reference Base for Soil Resources (WRB), United States Department of Agriculture (USDA) Soil Taxonomy and land capability classification. The variability of soils across the different sites was subsequently analysed using the coefficient of variation (CV). The results show that the variability of sand across the study sites was moderate (20 – 21 %), silt was high (63 %), clay ranged from moderate (34 %) to high (52 %), while hydraulic conductivity was very high (128 – 144 %). Similarly, with regards to the chemical properties, soil pH and base saturation ranged from moderate (20 – 49 %) to high (52 %), while effective cation exchange capacity (ECEC) and aluminium saturation were high (70 – 77 %). It was concluded that the soils of southeastern Nigeria are very heterogeneous. Undue generalization should consequently be discouraged.

Virtual analyzer of extractive content in Eucalyptus wood based on hybrid modeling approach for the pulp and paper industry

This paper is aimed to develop a hybrid model (PCA-ANN) to predict the extractive content in eucalyptus wood clones. The input variables to the virtual analyzer are planting parameters available from the forest inventory, therefore the prediction does not rely on laboratory analysis of the wood samples, affording a quick estimate of the extractive contents. This study further bridges the literature gap on the investigation of the cause of variability of extractive content in eucalyptus wood. The PCA-ANN was identified from experimental data to predict and monitor the extractive content, since laboratory measurements can take several days and become available only after wood processing. The experimental data contained information on ten species of eucalyptus clones from five regions in the extreme south of Bahia, Brazil. Principal Component Analysis (PCA) firstly assessed the impact of planting variables on the extractives content. The variability of the data was represented by eight principal components and the variables that mostly contribute to the extractive content are: potential acidity, iron, saturation of aluminum, magnesium, pH, base saturation, remaining phosphorus, zinc, manganese and copper. The artificial neural network (ANN) with the 8 principal components in the input layer showed that the PCA could effectively reduce the dimensionality of the data. For practical purposes, though, the ANN with 10 input variables and 16 neurons in the hidden layer, presenting an average relative deviation of 1.5%, is recommended. The prediction of the extractive content is essential to allow preventive management practices toward the improvement of yield and quality of the cellulosic pulp.

Phosphorus availability and exchangeable aluminum response to phosphate rock and organic inputs in the Central Highlands of Kenya

Soil acidity and phosphorus deficiency are some of the constraints hampering agricultural production in tropical regions. The prevalence of soil acidity is associated with phosphorus (P) insufficiency and aluminum saturation. We conducted a two-seasons experiment to evaluate soil phosphorus availability and exchangeable aluminum in response to phosphate rock and organic inputs in acidic humic nitisols. The field experiment was installed in Tharaka Nithi County in the Central Highlands of Kenya. The experimental design was a randomized complete block design with treatments replicated thrice. The treatments were: Green manure (Tithonia diversifolia Hemsl.) (60 kg P ha−1), phosphate rock (60 kg P ha−1), goat manure (60 kg P ha−1), Tithonia diversifolia (20 kg P ha−1) combined with phosphate rock (40 kg P ha−1), manure (20 kg P ha−1) combined with phosphate rock (40 kg P ha−1), Triple Super Phosphate combined with Calcium Ammonium Nitrate (TSP + CAN) (60 kg P ha−1) and a control (no input). During the long rains of the 2018 season (LR2018), Tithonia diversifolia + phosphate rock had a significantly higher reduction (67%) of exchangeable aluminum than the sole use of Tithonia diversifolia. Grain yield under TSP + CAN was the highest, followed by the sole organics during the LR2018. Tithonia diversifolia + phosphate rock resulted in a 99% and a 90% increase in NaHCO3-Pi compared to sole phosphate rock and sole Tithonia diversifolia, respectively. Tithonia diversifolia led to 14% and 62% higher resin-Pi and NaOH-Pi, respectively, compared to manure in the short rains of 2017 (SR2017). The increase in NaOH-Po after the two seasons was statistically significant in sole TSP + CAN. Based on the observed reduced exchangeable aluminum and additional nutrients like Ca, Mg, and K in the soil, sole organic inputs or in combination with phosphate rock treatments are feasible alternatives for sustaining soil phosphorus. Our findings underscore an integrated approach utilizing organic amendments combined with phosphate rock in acidic humic nitisols' phosphorus nutrient management.

ANALISIS KANDUNGAN UNSUR HARA DAN TOTAL MIKROBA TANAH BEKAS PENAMBANGAN EMAS TANPA IZIN (PETI) DARI BEBERAPA KECAMATAN KABUPATEN KUANTAN SINGINGI

This unlicensed gold mining activity (PETI) can have a positive impact on the economy of the community, in the form of increased incomes so that it can improve the welfare of the community. However, besides having a positive impact, PETI's activities will harm the environment around the mining area. The negative impact caused by mining activities is environmental damage in the form of a decrease in land quality as indicated by a decrease in physical, chemical and biological soil quality. The purpose of this study was to determine the nutrient content and the total of microbes in former PETI soils in sub-districts of the Kuantan Singingi Regency. The parameters observed were analysis of nutrient content consisting of analysis of sand, dust, clay, soil pH, C-organic, N-total, P2O5, K2O, interchangeable cations, CEC, a saturation of bases, Aluminum Saturation, and analysis of total soil microbes. The results showed that the Singingi sub-district, Central Kuantan sub-district, Sentoja sub-district, and Logas Tanah Darat sub-district has the texture of sand soil clay to sand, the content of pH H2O Land classified as fertility is very sour, C-Organic (%), Ca-dd, Nitrogen-Total (%), Mg-dd and CEC with very low fertility criteria, C/N Ratio with low to very low fertility criteria, K-dd content with low criteria, Na-dd with moderate to very high criteria, aluminum saturation is very high with wet saturation the fertility criteria are low. The total microbes in the Sub-district of Sentoja Raya and Logas Tanah Darat Sub-district are much higher than Singingi Sub-district and Central Kuantan Sub-district.

Zircon U–Pb ages, geochemistry, and Sr–Nd–Pb–Hf isotopes of the Mugagangri monzogranite in the southern Qiangtang of Tibet, western China: Implications for the evolution of the Bangong Co‐Nujiang Meso‐Tethyan Ocean

We present in‐situ zircon laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) U–Pb ages, whole‐rock geochemistry, and Sr–Nd–Pb–Hf isotopes of the Mugagangri monzogranite in the southern margin of the Qiangtang Block, Tibet, western China. The zircons yield a U–Pb age of ca. 123 Ma. The hornblende‐bearing monzogranite shows metaluminous to weak peraluminous and high‐K calc‐alkaline characteristics exemplified by high silica (SiO2 = 67.57–70.57 wt%), high aluminium (Al2O3 = 14.68–15.78 wt%), high potassium (K2O = 4.00–5.14 wt%), high alkali (K2O + Na2O = 7.88–8.62 wt%), and low calcium contents (CaO = 1.72–2.17 wt%), with the aluminium saturation index (A/CNK) ranging from 0.98 to 1.09, suggesting that the Mugagangri monzogranite is a metaluminous to weak peraluminous I‐type high‐K calc‐alkaline granite. Geochemically, similar to the arc magmas, the monzogranite is enriched in large‐ion lithophile elements, and relatively depleted in high‐field‐strength elements. The monzogranite displays relatively high (87Sr/86Sr)i values (0.70972–0.71240), uniform εNd(t) values (−2.24 to −3.40), variable zircon εHf(t) values (−14.1 to +8.0), and high radiogenic Pb isotopic values (206Pb/204Pb = 18.588–18.790, 207Pb/204Pb = 15.616–15.642, and 208Pb/204Pb = 38.838–39.053). These geochemical characteristics indicate that the monzogranite was derived from a mixed source comprising ancient crustal and mantle materials, and experienced fractional crystallization during emplacement. We propose that the parental magma of the Mugagangri monzogranite was most likely generated during northward subduction of the Bangong Co‐Nujiang Meso‐Tethys Ocean.

Geochronology and petrogenesis of the Late Triassic A-type granitoids in the Yeongnam Massif and its implication for Late Triassic geodynamics of northeast Asia

The Late Triassic A-type granitoids along the continental margins of East Asia are important for deciphering the crust-mantle interactions, transformation of tectonic regime, and termination of the Indosinian Orogeny (known as the Songrim Orogeny in South Korea). The newly identified Wangdong plutons are distributed in the southwestern part of Yeongnam Massif, South Korea. U–Pb dating of zircons from the Wangdong plutons has established its date of emplacement at ca. 226–221 Ma, similar to the emplacement ages of the Daegang and Ian alkali granites. Geochemical data have shown that the Wangdong granitoid samples are magnesian to ferroan in composition and can be further classified in the range from alkalic to calc-alkalic. They have a high zircon saturation temperature (~ 850 °C), K2O/Na2O and, Ga/Al ratios, and are enriched with high field strength elements (e.g., Zr and Y), indicating an A-type granite affinity. Their classification into A2-type granites based on the A-type subdivision diagrams suggest that they formed in an extension-related tectonic setting. Moreover, the Wangdong A-type granitoids have high (La/Nb)N and (Th/Nb)N ratios with peraluminous characteristics (value of aluminum saturation index >1.0). In addition, magmatic zircons from the Wangdong granitoids have negative ɛHf(t) values (−6.6 to −15.5) with a Paleoproterozoic to Mesoproterozoic two-stage Hf model ages (from 1.99 to 1.49 Ga). This suggests that the Wangdong granitoids were derived from ancient crustal materials with compositions similar to metagraywackes. Based on geochemical, isotopic, and geochronological studies, we concluded that the lithospheric mantle delamination induced by slab roll-back of the subducted Paleo-Pacific plate is the main trigger in the production of Late Triassic magmatism in Yeongnam Massif, South Korea.

Development and Nutrient Uptake by Physalis under Different Soil Water Tensions

ABSTRACT The water deficit generated by inadequate management of irrigation can affect the development and yield of crops. However, little is known about irrigation and irrigation management for physalis (Physalis peruviana L.). The objective of this work was to study different soil water tensions as an indicative for irrigation management in physalis crop and to evaluate its effects on crop development and yield, nutrient uptake, and soil chemical attributes. The experiment was conducted in field condition, soil Typic Quartzipsamment. A randomized block design with four soil water tensions (10, 20, 30, and 40 kPa) was used with four blocks and two replications of treatments per block. In order to monitor the soil water tensions, tensiometers were installed at a depth of 0.20 m. Increased soil water tension led to reduced growth and fruit productivity of physalis. Leaf concentrations of nitrogen (N) and potassium (K) increased, calcium (Ca), magnesium (Mg), sulfur (S), boron (B), iron (Fe), manganese (Mn) and zinc (Zn) reduced, and phosphorus (P) and copper (Cu), were not influenced by increased soil water tension. Values of soil pH, P, K, Ca and Mg and base saturation increased, while exchangeable aluminum (Al) and Al saturation decreased with increases in soil water tensions. The highest development and nutrient uptake of the physalis crop were under soil water tension of 10 kPa at 0.20 m deep. It was concluded that, for the evaluated soil, the irrigation management recommended for conducting the physalis crop is with the soil moisture close to the field capacity.

Generation of syn-collisional S-type granites in collision zones: An example from the Late Triassic Tanggula Batholith in northern Tibet

Mechanisms of syn-collision magma generation are unclear due to the uncertainty in defining the term collision. We address this issue by presenting detailed petrographic, chronological, and geochemical data for the Tanggula Batholith located immediately to the north of the Longmu Tso–Shuanghu suture zone (LSSZ) in northern Tibet. Zircon LA–ICPMS U–Pb dating suggests that the Tanggula Batholith was emplaced at 235–226 Ma. Samples from the batholith show variable SiO2 of 66.6–80.6 wt% and are characterized by high normative corundum (1.09–4.35 wt%) and high aluminum saturation index (A/CNK = 1.05–1.40). These samples exhibit high initial 87Sr/86Sr (0.7165–0.7214), negative whole-rock εNd(t) (−10.1 to −8.5), εHf(t) (−8.7 to −6.3), enriched Pb isotope compositions, and variable zircon εHf(t) values (−29.9 to +5.6), as well as variable zircon δ18O value (6.90–9.22‰). These signatures are characteristic of S-type granites, and were derived from anataxis of metasedimentary rocks from the Qiangtang Terrane with input from mantle-derived components. We propose that the Tanggula Batholith was emplaced in a syn-collisional setting following closure of the Longmu Tso–Shuanghu Ocean along a north dipping subduction zone based on: the timing of high-pressure, low-temperature metamorphism at 244–221 Ma marking collision between Southern and Northern Qiangtang; the timing of exhumation of metamorphic rocks at ~223–204 Ma; and, bimodal volcanism (225–202 Ma) associated with slab breakoff at 220–215 Ma.

Chemical changes in soil with use of pelletized organomineral fertilizer made from biosolids and sugarcane filter cake

Soil fertility has become an interconnected aspect of modern agriculture, incorporating factors such as nutrient availability from soil, and its revision has become necessary for ensuring sustainability. Therefore, to understand the solubility of nutrients from organomineral fertilizers pelleted with biosolids and sugarcane filter cake, and to evaluate the resulting chemical changes in soil from its use, an experiment was performed in a completely randomized design. The experiment was done with four replicates in a 3 × 5 +1 factorial scheme, using three fertilizer sources (mineral fertilizer, organomineral fertilizer pelletized with biosolids, and organomineral fertilizer pelletized with the filter cake); five doses (60%, 80%, 100%, 120%, and 140% of the recommended dose of fertilization for corn); and an additional control treatment (absence of fertilization). The formulation of the organomineral fertilizers was 5-17-10 with 10% total organic carbon. All fertilizer sources were packed in a microfiber cloth positioned 1 cm below the surface of the soil and incubated for 60 days. Subsequent evaluation of chemical attributes: pH H2O (1:2.5); pH SMP (Shoemaker-McLean-Pratt); and the content of exchangeable aluminum, phosphorus, potassium, calcium, magnesium, silica, and organic matter within the soil was done. Organomineral fertilizers pelleted with biosolids or filter cake do not acidify the soil, but they were found to reduce aluminum saturation and promote a slow release of nutrients, which allowed a more balanced base in the soil. This then ensured a better balance of nutrients, with greater cation exchange capacity, base sums, and base saturation. The use of these fertilizers can contribute to stabilizing the pH of the soil with fewer applications of acidity correctives

Triassic granitoids in the East Kunlun Orogenic Belt, Northwestern China: magmatic source and implications for geodynamic evolution

ABSTRACT Granitoids, an important part of the continental crust, are the direct and indelible evidence of the accretion and reworking process of the continental crust in different tectonic settings. Therefore, these early geodynamic mechanisms can be roughly reconstructed by analysing the geochemical characteristics of granitoids. In this study, the Permian–Triassic Granitoids widely distributed in the East Kunlun Orogenic Belt (EKOB) are studied to determine their chronology and petrogenesis to restrict their source regions and establish the significance of their geodynamic and crustal growth. Zircon inductively coupled plasma mass spectrometry (ICP–MS) dating results show that the crystallization ages of these granitoids are between 252–240 Ma, during the early and middle Triassic. These granitoids have high SiO2 and medium Na2O + K2O contents, plotting into the granite region, and calc-alkaline to high-K calc-alkaline series on the SiO2–Na2O + K2O and SiO2–K2O diagrams, respectively. All the samples have aluminium saturation index (A/CNK) values from 1.00 to 1.25 showing peraluminous characteristics. In terms of trace and rare earth elements, the samples are depleted in high field strength elements (HFSEs) such as Nb, Ta, P, and Ti and are enriched in large ion lithophile elements (LILEs) such as Rb, K, Ba, and U. Moreover, all granitoids show right-inclined rare earth element (REE) distribution patterns with weak to moderate Eu anomalies (δEu = 0.50–0.93). In addition, the samples have low P2O5 contents, 10,000*Ga/Al ratios (1.65–2.39), and Zr + Nb + Ce + Y (212–262 ppm) displaying affinities to I-type granite. Combined with their εHf (t) values of −2.31 to 4.44, with 1.0–1.4 Ga two stage model ages (TDM2), they are considered to be the products of the reworking of the Mesoproterozoic lower crust; therefore, they are not related to the continental net growth in the EKOB. On the tectonic discrimination diagrams of granitoids, all the samples fall into the area of volcanic arc granite (VAG) and continental margin arc; this suggests that the Paleo-Tethys Ocean slab was still in the subduction stage during 252–240 Ma, and the continental collision had not yet started. Based on the plenty of magmatic rock dating results published previously, it appears there are two magmatic peak periods (260–240 Ma and 230–210 Ma) and one magmatic intermittence period (240–230 Ma) during the late Permian to Triassic of the EKOB, corresponding to three geodynamic evolution stages of subduction, post-collision extension, and syn-collision, respectively.

Age and geochemistry of the granitoid from the Lunte area, Northeastern Zambia: Implications for magmatism of the Columbia supercontinent

The Paleoproterozoic tectonic evolution of the Bangweulu Block has long been controversial. Paleoproterozoic granites consisting of the basement complex of the Bangweulu Block are widely exposed in northeastern Zambia, and they are the critical media for studying the tectonic evolution of the Bangweulu Block. This study systematically investigated the petrography, zircon U-Pb chronology, and petrogeochemistry of the granitoid extensively exposed in the Lunte area, northeastern Zambia. The results show that the granitoid in the area formed during 2051±13–2009±20 Ma as a result of Paleoproterozoic magmatic events. Geochemical data show that the granites in the area mainly include syenogranites and monzogranites of high-K calc-alkaline series and are characterized by high SiO2 content (72.68% –73.78%) and K2O/Na2O ratio (1.82–2.29). The presence of garnets, the high aluminum saturation index (A/CNK is 1.13–1.21), and the 1.27%–1.95% of corundum molecules jointly indicate that granites in the Lunte area are S-type granites. Rare earth elements in all samples show a rightward inclination and noticeably negative Eu-anomalies (δEu = 0.16–0.40) and are relatively rich in light rare earth elements. Furthermore, the granites are rich in large ion lithophile elements such as Rb, Th, U, and K and are depleted in Ba, Sr, and high field strength elements such as Ta and Nb. In addition, they bear low contents of Cr (6.31×10−6–10.8×10−6), Ni (2.87×10−6–4.76×10−6), and Co (2.62×10−6–3.96×10−6). These data lead to the conclusion that the source rocks are meta-sedimentary rocks. Combining the above results and the study of regional tectonic evolution, the authors suggest that granitoid in the Lunte area were formed in a tectonic environment corresponding to the collision between the Tanzania Craton and the Bangweulu Block. The magmatic activities in this period may be related to the assembly of the Columbia supercontinent.©2021 China Geology Editorial Office.

Using Soil Quality Index Plus to assess soil conditions and limiting factors for dryland farming

Agriculture 3.0 and Agriculture 4.0 requires appropriate agricultural practices, including soil data that are practical, accurate, and easy to understand. Using soil type maps and land suitability class maps for soil information not only challenges users but also does not provide soil quality information such as production potential and plant growth and production inhibitors. Other techniques that can provide more appropriate soil information for agricultural purposes are thus needed. This research suggests the soil assessment system Soil Quality Index Plus, which provides accessible information regarding soil conditions and plant growth and production inhibitors in the context of dryland farming. Field trials were conducted in 36 locations across five regencies in West Java, Indonesia. Soil Quality Index Plus accurately assessed soil quality by using 11 key parameters as a dataset: effective depth, texture class, bulk density, drainage, pH, cation exchange capacity, total organic nitrogen, available phosphate, exchangeable potassium, aluminum saturation, and total carbon organic. The majority of the soils studied were classified as medium soil quality, with low organic carbon being the most common limiting factor. Improved fertilizer management, especially the use of organic fertilizers, phosphate- and nitrogen-based fertilizers, and agricultural lime should be implemented in particular areas.

Evaluation of Soil Ameliorants on Immature and Mature Oil Palms in Acidic Peat

Although peat soil has a low pH range of 3.2 to 3.8 units, it remains unclear whether this is a major constraint to oil palm cultivation, as the cultivar is known to tolerate fairly high levels of acidity without any serious adverse effects. Earlier work on liming and acidity correction has often given conflicting and sometimes, even negative results. In view of the latter, two trials were established to evaluate a number of soil ameliorants and their impact if any, on the growth and yield of newly planted and young mature palms in deep acidic peat. This paper summarises results over a 7- year evaluation period. Of the four ameliorants evaluated on newly planted seedlings in trial no.1, limestone dust (LSD) was the most effective in correcting acidity, raising the soil pH from 3.6 to 5.4 - 6.1 units in the top 30 cm of soil. Despite the significant improvement in soil pH, no advantage in nutrient uptake, palm growth and fresh fruit bunch (FFB) yield was recorded over unlimed control plots. In contrast, oil palm bunch ash (BA), eucalyptus fly ash (EFA) and paddy husk ash (PHA) had a smaller impact on soil acidity, but increased FFB yield from 2 per cent to 9 per cent, of which BA was the most effective, especially at the higher rate of application (9.0 kg/palm/year). One negative aspect of acidity amelioration is its impact on peat subsidence. Being highly caustic, application of LSD and BA accelerated decomposition and mineralisation of the peat, increasing subsidence rates by as much as 1.0 cm per annum. In trial no.2 which evaluated two potash sources [muriate of potash (MOP) and BA] on young mature palms, only annual applications of BA significantly improved soil pH, requiring up to 9.0 kg per palm per year to improve and maintain top soil pH above 5.0 units. BA was also superior to MOP in improving soil fertility, particularly the levels of exchangeable potassium, calcium and magnesium and also significantly reduced the concentration of free aluminium ions and aluminium saturation to low or negligible levels. Although BA ameliorated soil acidity and significantly improved soil fertility, no significant differences in FFB yield were recorded between BA and MOP. With MOP, response to fertiliser inputs was linear, highest yield being achieved with 6.0 kg per palm per year. In contrast, no significant differences were recorded between the different BA rates applied, with 4.50 kg per palm per year producing the same yield response as the highest rate of 11.25 kg per palm per year. For peat soil, BA appeared to be the more efficient K source, as it could attain the same yield as MOP, but at lower K inputs. As peat is reported to be very deficient in silica, it is suspected that any positive responses elicited by application of ash products (which have high silica content) could be a response to silica rather than correction in soil acidity. However, as no soil, foliar and product analysis was carried out for silica content in both trials, the latter will remain a hypothesis until proven otherwise. Trials are currently underway to evaluate the impact of silica on oil palm growth and yield in peat soils. Keywords: Acidity, bunch ash, oil palm, peat, soil amelioration.