scholarly journals Characterization of Weathering Processes of the Giant Copper Deposit of Tizert (Igherm Inlier, Anti-Atlas, Morocco)

Minerals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 620
Author(s):  
Julien Poot ◽  
Michèle Verhaert ◽  
Augustin Dekoninck ◽  
Abdellah Oummouch ◽  
Abdelaziz El Basbas ◽  
...  
Keyword(s):  
Copper Deposit ◽  
Weathering Processes ◽  
Supergene Enrichment ◽  
Oxide Zone ◽  
The World ◽  
Weathered Rocks ◽  
Fe Oxyhydroxides ◽  
Ph Conditions ◽  
Host Rocks

The giant Tizert copper deposit is considered as the largest copper resource in the western Anti-Atlas (Morocco). The site is characterized by Cu mineralization carried by malachite, chalcocite, covellite, bornite and chalcopyrite; azurite is not observed. The host rocks are mainly limestones (Formation of Tamjout Dolomite) and sandstones/siltstones (Basal Series) of the Ediacaran/Cambrian transition. The supergene enrichment is most likely related to episodes of uplift/doming (last event since 30 Ma), which triggered the exhumation of primary/hypogene mineralization (chalcopyrite, pyrite, galena, chalcocite I and bornite I), generating their oxidation and the precipitation of secondary/supergene sulfides, carbonates and Fe-oxyhydroxides. The Tizert supergene deposit mainly consists of (i) a residual patchwork of laterite rich in Fe-oxyhydroxides; (ii) a saprolite rich in malachite, or “green oxide zone” where primary structures such as stratification are preserved; (iii) a cementation zone containing secondary sulfides (covellite, chalcocite II and bornite II). The abundance of Cu carbonates results from the rapid neutralization of acidic meteoric fluids, due to oxidation of primary sulfides, by carbonate host rocks. Chlorite is also involved in the neutralization processes in the sandstones/siltstones of the Basal Series, in which supergene clays, such as kaolinite and smectites, subsequently precipitated. At Tizert, as can be highlighted in other supergene Cu-deposits around the world, azurite is absent due to low pCO2 and relatively high pH conditions. In addition to copper, Ag enrichment is also observed in weathered rocks; Fe-oxyhydroxides contain high Zn, As, and Pb contents. However, these secondary enrichments are quite low compared to Cu in the whole Tizert site, which is therefore, considered as relatively homogeneous.

scholarly journals Application of fractal models to delineate mineralized zones in the Pulang porphyry copper deposit, Yunnan, southwestern China

2019 ◽  
Vol 26 (3) ◽  
pp. 267-282 ◽  
Author(s):  
Xiaochen Wang ◽  
Qinglin Xia ◽  
Tongfei Li ◽  
Shuai Leng ◽  
Yanling Li ◽  
...  
Keyword(s):  
Porphyry Copper ◽  
Copper Deposit ◽  
Porphyry Copper Deposit ◽  
Southwestern China ◽  
Fast Fourier Transformation ◽  
Fractal Models ◽  
Supergene Enrichment ◽  
S Model ◽  
Host Rocks ◽  
Log Ratio

Abstract. The aim of this study is to delineate and identify various mineralized zones and barren host rocks based on surface and subsurface lithogeochemical data from the Pulang porphyry copper deposit, southwestern China, utilizing the number–size (N-S), concentration–volume (C-V) and power-spectrum–volume (S-V) fractal models. The N-S model reveals three mineralized zones characterized by Cu thresholds of 0.28 % and 1.45 %: <0.28 % Cu represents weakly mineralized zones and barren host rocks, 0.28 %–1.45 % Cu represents moderately mineralized zones, and > 1.45 % Cu represents highly mineralized zones. The results obtained by the C-V model depict four geochemical zones defined by Cu thresholds of 0.25 %, 1.48 % and 1.88 %, representing nonmineralized wall rocks (Cu<0.25 %), weakly mineralized zones (0.25 %–1.48 %), moderately mineralized zones (1.48 %–1.88 %) and highly mineralized zones (Cu>1.88 %). The S-V model is used by performing a 3-D fast Fourier transformation of assay data in the frequency domain. The S-V model reveals three mineralized zones characterized by Cu thresholds of 0.23 % and 1.33 %: <0.23 % Cu represents leached zones and barren host rocks, 0.23 %–1.33 % Cu represents hypogene zones, and >1.33 % Cu represents supergene enrichment zones. All the multifractal models indicate that high-grade mineralization occurs in the central and southern parts of the ore deposit. Their results are compared with the alteration and mineralogical models resulting from the 3-D geological model using a log-ratio matrix. The results show that the S-V model is best at identifying highly mineralized zones in the deposit. However, the results of the C-V model for moderately and weakly mineralized zones are also more accurate than those obtained from the N-S and S-V models.

CHARACTERIZATION OF PALEOPROTEROZOIC STRUCTURES, AURIFEROUS QUARTZ VEINS, AND HOST ROCKS, FISHER PROPERTY, SEABEE GOLD OPERATION, SASKATCHEWAN, CANADA

2019 ◽  
Author(s):  
Courtney Carol Onstad ◽  
◽  
Kevin M. Ansdell ◽  
Camille A. Partin ◽  
Anders Carlson
Keyword(s):  
Quartz Veins ◽  
Host Rocks

scholarly journals The absence of the caffeine synthase gene is involved in the naturally decaffeinated status of Coffea humblotiana, a wild species from Comoro archipelago

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nathalie Raharimalala ◽  
Stephane Rombauts ◽  
Andrew McCarthy ◽  
Andréa Garavito ◽  
Simon Orozco-Arias ◽  
...  
Keyword(s):  
Wild Species ◽  
Illegitimate Recombination ◽  
Recombination Mechanism ◽  
Comparative Analyses ◽  
Robusta Coffee ◽  
Caffeine Synthase ◽  
The World ◽  
Decaffeinated Coffee ◽  
Chromosome Level

AbstractCaffeine is the most consumed alkaloid stimulant in the world. It is synthesized through the activity of three known N-methyltransferase proteins. Here we are reporting on the 422-Mb chromosome-level assembly of the Coffea humblotiana genome, a wild and endangered, naturally caffeine-free, species from the Comoro archipelago. We predicted 32,874 genes and anchored 88.7% of the sequence onto the 11 chromosomes. Comparative analyses with the African Robusta coffee genome (C. canephora) revealed an extensive genome conservation, despite an estimated 11 million years of divergence and a broad diversity of genome sizes within the Coffea genus. In this genome, the absence of caffeine is likely due to the absence of the caffeine synthase gene which converts theobromine into caffeine through an illegitimate recombination mechanism. These findings pave the way for further characterization of caffeine-free species in the Coffea genus and will guide research towards naturally-decaffeinated coffee drinks for consumers.

scholarly journals Theoretical and Empirical Characterization of Water as a Factor: Examples and Related Issues with the World Trade Model

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 459
Author(s):  
Ignacio Cazcarro ◽  
Albert E. Steenge
Keyword(s):  
World Trade ◽  
Low Cost ◽  
Virtual Water ◽  
Considerable Change ◽  
Water Research ◽  
Trade Model ◽  
The World ◽  
Main Model ◽  
Selection Of

This article originates from the theoretical and empirical characterization of factors in the World Trade Model (WTM). It first illustrates the usefulness of this type of model for water research to address policy questions related to virtual water trade, water constraints and water scarcity. It also illustrates the importance of certain key decisions regarding the heterogeneity of water and its relation to the technologies being employed and the prices obtained. With regard to WTM, the global economic input–output model in which multiple technologies can produce a “homogeneous output”, it was recently shown that two different mechanisms should be distinguished by which multiple technologies can arise, i.e., from “technology-specific” or from “shared” factors, which implies a mechanism-specific set of prices, quantities and rents. We discuss and extend these characterizations, notably in relation to the real-world characterization of water as a factor (for which we use the terms technology specific, fully shared and “mixed”). We propose that the presence of these separate mechanisms results in the models being sensitive to relatively small variations in specific numerical values. To address this sensitivity, we suggest a specific role for specific (sub)models or key choices to counter unrealistic model outcomes. To support our proposal we present a selection of simulations for aggregated world regions, and show how key results concerning quantities, prices and rents can be subject to considerable change depending on the precise definitions of resource endowments and the technology-specificity of the factors. For instance, depending on the adopted water heterogeneity level, outcomes can vary from relatively low-cost solutions to higher cost ones and can even reach infeasibility. In the main model discussed here (WTM) factor prices are exogenous, which also contributes to the overall numerical sensitivity of the model. All this affects to a large extent our interpretation of the water challenges, which preferably need to be assessed in integrated frameworks, to account for the main socioeconomic variables, technologies and resources.

Area Studies and Desire: Towards a Genealogy

1997 ◽  
Vol 1 (1) ◽  
pp. 52-65
Author(s):  
Hye-Joon Yoon
Keyword(s):  
Chinese Culture ◽  
Geographical Area ◽  
Academic Research ◽  
Past Century ◽  
Area Studies ◽  
Western Area ◽  
The World ◽  
38Th Parallel ◽  
The One

Area studies, as a newly fashionable field of academic research, needs to recognize its less likely precedents if it is going to secure for itself a fresh start. The question of “desire” is relevant here because it indicates the less value-free aspects in its genealogy. As shown in Emma Bovary's embellished representation of Paris at her provincial home, an understanding of an area often reflects the particular needs and desires of the one who understands that area. Such restricted and restricting views of an area repeats itself outside the world of literary fictions, as is shown by the example of Guizot's picture of Europe in which his own country is given a privileged place as the very center of Western civilization itself. An instructive case showing the thin line between the projected desire of one who strives to know a geographical area and the scientific purity of the labor itself is further offered by Napoleon Bonaparte's heavy reliance on Orientalist scholarship in his invasion of Egypt. Moving further east from Egypt to China, we witness the denigrating remarks on China made by the great German thinkers of the past century, Hegel and Weber. Although their characterization of Chinese culture could find echoes in unbiased empirical research, they reveal all the same the trace of Europeans' desire to affirm their superiority over the supposedly inferior and false civilization of the East. Similarly, the Americans who divided the Korean peninsular at the 38th Parallel, with unquestioning confidence in their knowledge of the area and in the justice of their action, rightfully deserve their place in the tradition of Western area studies of serving the needs to dominate, control and exploit an objectified overseas territory. He assumed that words had kept their meaning, that desires still pointed in a single direction, and that ideas retained their logic; and he ignored the fact that the world of speech and desires has known invasions, struggles, plundering, disguises, ploys. From these elements, however, genealogy retrieves an indispensable restraint: it must record the singularity of events outside of any monotonous finality; it must seek them in the most unpromising places, in what we tend to feel is without history—in sentiments, love, conscience, instincts; it must be sensitive to their recurrence, not in order to trace the gradual curve of their evolution, but to isolate the different scenes where they engaged in different roles. — Michel Foucault, “Nietzsche, Genealogy, History” (Foucault 139–40).

scholarly journals Characterization of three soybean landraces resistant to Asian soybean rust disease

2020 ◽  
Vol 40 (6) ◽  
Author(s):  
Luciano Nobuhiro Aoyagi ◽  
Yukie Muraki ◽  
Naoki Yamanaka
Keyword(s):  
Susceptible Variety ◽  
Soybean Rust ◽  
Resistance Locus ◽  
Chromosome 6 ◽  
Phakopsora Pachyrhizi ◽  
Rust Disease ◽  
Asian Soybean Rust ◽  
The World ◽  
Trait Locus

Abstract Phakopsora pachyrhizi is an obligatory biotrophic fungus that causes Asian soybean rust (ASR) disease. ASR control primarily involves chemical control and the use of resistant soybean cultivars carrying an Rpp (resistance to P. pachyrhizi) gene. This study aimed to characterize the ASR resistance of three soybean Asian landraces. By screening the world core collection (WC) of soybean, which consists of 80 varieties, three landraces were identified in Southeast Asia as resistant to ASR. Genetic mapping using the F2 population derived from a cross with an ASR-susceptible variety, BRS 184, indicated that KS 1034 (WC2) has ASR resistance conferred by a single dominant resistance gene, mapped on chromosome 18, in the same region where Rpp1 was mapped previously. The BRS 184 × WC61 (COL/THAI/1986/THAI-80) F2 population, on the other hand, showed an ASR resistance locus mapped by quantitative trait locus analysis on chromosome 6, in the region where the resistance conferred by PI 416764 Rpp3 resides, with a logarithm of the odds score peak at the same position as the marker, Satt079, while the BRS 184 × WC51 (HM 39) population showed the resistance to ASR allocated between Satt079 and Sat_263 markers, also in the region where Rpp3 was mapped previously. Both WC51 and WC61 have the same infection profile as FT-2 and PI 462312 when tested against the same ASR isolate panel. These three WCs can be used in MAS programs for introgression of Rpp1 and Rpp3 and the development of ASR-resistant cultivars in the breeding program.

scholarly journals The crisis of content verbality in Internet discourse

2021 ◽  
pp. 224-228
Author(s):  
Марина Михайловна Молчанова ◽  
Патимат Абдулаевна Лекова
Keyword(s):  
Social Networks ◽  
Computer Technology ◽  
Linguistic Competence ◽  
The Internet ◽  
The World ◽  
Younger Generation ◽  
Media Texts ◽  
Active Visualization ◽  
First Time

Исследуется кризис вербальности контента в интернет-дискурсе, его активная визуализация, связанная с новыми открытиями в области компьютерных технологий. Цель работы - дать полиаспектную характеристику этому явлению и обозначить перспективы его влияния на речемыслительную деятельность подрастающего поколения, составляющего большую часть пользователей социальных сетей. Актуальность данной проблематики обусловлена обеспокоенностью филологической общественностью тем, что мир становится все менее лингвистическим. Новизна заключается в том, что впервые интернет-дискурс рассматривается в контексте кризиса вербальности контента. При таких темпах визуализации медиатекстов вполне вероятно обострение кризиса вербальности, последствия которого могут негативно сказаться на мыслетворческой деятельности у подрастающего поколения, которая возможна только при высокой языковой компетенции. The paper examines the crisis of content verbality in the Internet discourse, its active visualization associated with new discoveries in the field of computer technology. The aim of the work is to give a multi-aspect characterization of this phenomenon and outline the prospects of its influence on the speech-thinking activity of the younger generation, which makes up the majority of users of social networks. The relevance of this issue is due to the concern of the philological community that the world is becoming less and less linguistic. The novelty lies in the fact that for the first time Internet discourse is considered in the context of the crisis of content verbality. At such a rate of visualization of media texts, it is likely that the crisis of verbality will aggravate, the consequences of which can negatively affect the thinking activity of the younger generation, which is possible only with high linguistic competence.

Sign in / Sign up

Export Citation Format

Share Document