scholarly journals Gold deposits of Suriname: geological context, production and economic significance

2016 ◽  
Vol 95 (4) ◽  
pp. 429-445 ◽  
Author(s):  
Nicole M. E. Kioe-A-Sen ◽  
Manfred J. van Bergen ◽  
Theo E. Wong ◽  
Salomon B. Kroonenberg
Keyword(s):  
Greenstone Belt ◽  
Gold Deposits ◽  
Point Of View ◽  
Open Pit ◽  
Small Scale ◽  
Ore Formation ◽  
Economic Significance ◽  
History Of ◽  
Greenstone Belts ◽  
Available Information

AbstractGold has been a major economic asset for Suriname for more than a century. The long history of gold mining, concentrated in large parts of a greenstone belt in the northeast of the country, began with small-scale artisanal extraction activities and has recently seen the development of major open-pit operations. Despite the range of mining activities, Suriname's gold deposits and occurrences are under-explored from a scientific point of view. Primary gold mineralisations in the greenstone belt occur in multiple forms, and although their origin is commonly related to the Palaeoproterozoic Trans-Amazonian orogeny, the controls of ore formation in specific cases often remain obscure. This contribution presents an abridged overview of currently available information on the geological setting and characteristics for some of the main deposits where gold is extracted. In view of the consistent link between gold metallogeny and granitoid–greenstone belts in the northern Guiana Shield, the mineralised settings in Suriname are discussed in a regional context.

scholarly journals Гермотим из Клазомен и начало афинской философии

2020 ◽  
Vol 53 (3) ◽  
pp. 141-148
Author(s):  
О.А. Матвейчев
Keyword(s):  
Ancient Greece ◽  
Fundamental Principle ◽  
History Of Philosophy ◽  
Point Of View ◽  
Greek Philosophy ◽  
History Of ◽  
The Difference ◽  
Classical Greek Philosophy ◽  
Available Information ◽  
Greek World

Гермотим из Клазомен – фигура в истории греческой философии, можно сказать, маргинальная. В современной литературе он появляется разве что в ряду других колдунов и мистиков VII–VI вв. до н.э. В таком статусе он включается и в собрание Дильса. Анализируя сведения о Гермотиме, автор ставит перед собой цель найти ему место среди малоазийских философов первой величины, которых считают основателями греческой философии. Различение духа (души) и материи (тела) станет основополагающим принципом греческой философии, понятие Ума (нуса) выступит фундаментом для системы Анаксагора, первого афинского философа, с которого, собственно, и начнется история классической греческой философии. Автор разделяет точку зрения Э. Доддса и др., что появление нового для Греции представления о различии души и тела коренится в северной (гиперборейской?) ментальности, привнесенной в греческий мир во времена колонизации VII–VI вв. до н.э., а возможно – и в более ранние. Ключевые слова: история философии, Древняя Греция, Гиперборея, Гермотим из Клазомен, Анаксагор, шаманизм, нус, душа, тело Hermotimus of Clazomenae can be called a marginal figure in the history of Greek philosophy. In modern literature he is mentioned only among other sorcerers and mystics of the VIIth–VIth centuries BC. The collection of Hermann Diels describes him in the same manner. Analyzing available information about Hermotimus, the author makes an attempt to place him among the primary Anatolian philosophers who are considered the founders of Greek philosophy. The distinction between spirit (soul) and matter (body) will become the fundamental principle of Greek philosophy; the concept of Nous (cosmic Mind) will be the foundation for the system of Anaxagoras, the first Athenian philosopher, from which, in fact, the history of classical Greek philosophy begins. The author shares the point of view of E. Dodds and others that the emergence of a new concept about the difference between soul and body in Greece is rooted in the northern (Hyperborean?) mentality introduced into the Greek world during the colonization of the VIIth–VIth centuries BC or possibly in earlier times. Keywords: history of philosophy, Ancient Greece, Hyperborea, Hermotimus of Clazomenae, Anaxagoras, shamanism, nous, soul, body

Structural evolution of the Hemlo greenstone belt in the vicinity of the world-class Hemlo gold deposit

2003 ◽  
Vol 40 (3) ◽  
pp. 395-430 ◽  
Author(s):  
T L Muir
Keyword(s):  
Gold Deposit ◽  
Greenstone Belt ◽  
Structural Evolution ◽  
Small Scale ◽  
Structural Elements ◽  
Shear Sense ◽  
History Of ◽  
Brittle Fractures ◽  
World Class ◽  
Dextral Shear

A complex history of volcano-sedimentary deposition, polyphase strain, multiple intrusive events, and various stages of porphyroblastesis is indicated for the Hemlo gold deposit area within the Hemlo greenstone belt. Structural elements can be assigned to at least six stages of development (D1–D6). D1 generated small-scale folds and low-angle faults (thrusts?) with no planar fabric, except within strain aureoles around the earliest intrusions. D2 was a progressive event resulting from northeast-directed compression, which generated regional, predominantly S-shaped folds (early D2); penetrative planar and linear fabrics, overturned stratigraphy, and formation of an inflection in the strike of the greenstone belt (mid-D2); and development of high-strain zones with dominant sinistral and local dextral shear sense (late D2). D3 was a distinctly separate progressive event resulting from northwest-directed transpression, which generated variably penetrative east- to northeast-striking foliation (S3), ductile dextral shear fabrics, and small-scale Z-shaped folds (early D3), followed by brittle–ductile to brittle development of cataclasite and pseudotachylite in layer-parallel zones (late D3). D4 resulted in contractional kinks and brittle fractures, locally in conjugate sets. D5 and D6 are represented by brittle to brittle–ductile faults, which overprint Paleoproterozoic and Mesoproterozoic dikes, respectively. Four granitoid magmatic events span the interval 2720–2677 Ma, with emplacement mainly during D2, between ca. 2690 and ca. 2684 Ma. A protracted period of regional medium-grade metamorphism likely spanned the D2–D3 stages. The Hemlo gold deposit was emplaced during mid-D2 and was largely controlled by D2 structural elements and competency contrast between rock units.

From Multinational to Transnational Banking

2016 ◽  
pp. 162-190
Author(s):  
Christopher Kobrak
Keyword(s):  
Social Economic ◽  
Small Scale ◽  
Banking Services ◽  
Financial Firms ◽  
Cross Border ◽  
Economic Significance ◽  
Recent Interest ◽  
Wide Range ◽  
History Of ◽  
Shed Light

This chapter traces the history of cross-border joint-stock banking over roughly the last 100 years. Putting that history into its larger political, social, economic contexts may help shed light on our financial architecture’s social and economic significance, and even its sustainability. Despite recent interest in multinationals and banking, less is known about the cross-border management of financial firms than about that of other sectors. This chapter argues that during this period cross-border banking morphed from an activity conducted primarily by legally separate entities and on a comparatively small scale to one that is dominated today by megabanks that internalize a wide range of banking services in many countries and in most money-centres. It is a complex story, involving regulatory, technological, and political change in specific nations and among them.

scholarly journals From pencil and eraser to blending materials and flipping the classroom: A short history of Teksredaksie and Text Editing

Literator ◽  
2018 ◽  
Vol 39 (2) ◽  
Author(s):  
Kris Van de Poel
Keyword(s):  
Student Evaluation ◽  
Critical Evaluation ◽  
Point Of View ◽  
Small Scale ◽  
Usability Study ◽  
Central Attention ◽  
Open Questions ◽  
Training Approach ◽  
Professional Profile ◽  
History Of

This article will take a historical perspective on the topic of text editing and highlight the following: (1) The origin and history of the Text Editing project and book productions in different languages (2003–2018) and (2) The latest programme developments from printed book to teaching with it, or learning from it and especially the development of a state-of-the-art training approach. In an attempt to evaluate whether these developments are defensible, also from the point of view of its users, a small-scale usability study was carried out among two groups of master’s degree students (N = 37) who undertook inverted and/or flipped-blended-collaborative text editing. As inverting classrooms with blended materials (online and contact) and introducing a collaborative approach to learning are innovative within this domain, the question of the programme’s effectiveness deserves central attention. Quantitative and qualitative student evaluation data (online Likert-scale questionnaire with open questions and critical evaluation reports) show that Text Editing is more than a well-founded theoretical guide or handbook. The programme is experienced as authentic and effective and has a high impact on the users’ self-efficacy and professional profile. As such the project is sustainable.

scholarly journals Intrusion-Associated Gold Systems and Multistage Metallogenic Processes in the Neoarchean Abitibi Greenstone Belt

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 261
Author(s):  
Lucie Mathieu
Keyword(s):  
Greenstone Belt ◽  
Gold Deposits ◽  
Hydrothermal Systems ◽  
Magmatic Fluid ◽  
Gold Deposition ◽  
Alkaline Magmatism ◽  
Abitibi Greenstone Belt ◽  
Metamorphic Fluids ◽  
Greenstone Belts ◽  
Gold Bearing

In gold-endowed greenstone belts, ore bodies generally correspond to orogenic gold systems (OGS) formed during the main deformation stage that led to craton stabilization (syntectonic period). Most OGS deposits postdate and locally overprint magmatic-hydrothermal systems, such as Au-Cu porphyry that mostly formed during the main magmatic stage (synvolcanic period) and polymetallic intrusion-related gold systems (IRGS) of the syntectonic period. Porphyries are associated with tonalite-dominated and sanukitoid plutons, whereas most IRGS are related to alkaline magmatism. As reviewed here, most intrusion-associated mineralization in the Abitibi greenstone belt is the result of complex and local multistage metallogenic processes. A new classification is proposed that includes (1) OGS and OGS-like deposits dominated by metamorphic and magmatic fluids, respectively; (2) porphyry and IRGS that may contain gold remobilized during subsequent deformation episodes; (3) porphyry and IRGS that are overprinted by OGS. Both OGS and OGS-like deposits are associated with crustal-scale faults and display similar gold-deposition mechanisms. The main difference is that magmatic fluid input may increase the oxidation state and CO2 content of the mineralizing fluid for OGS-like deposits, while OGS are characterized by the circulation of reduced metamorphic fluids. For porphyry and IRGS, mineralizing fluids and metals have a magmatic origin. Porphyries are defined as base metal and gold-bearing deposits associated with large-volume intrusions, while IRGS are gold deposits that may display a polymetallic signature and that can be associated with small-volume syntectonic intrusions. Some porphyry, such as the Côté Gold deposit, demonstrate that magmatic systems can generate economically significant gold mineralization. In addition, many deposits display evidence of multistage processes and correspond to gold-bearing or gold-barren magmatic-hydrothermal systems overprinted by OGS or by gold-barren metamorphic fluids. In most cases, the source of gold remains debated. Whether magmatic activity was essential or marginal for fertilizing the upper crust during the Neoarchean remains a major topic for future research, and petrogenetic investigations may be paramount for distinguishing gold-endowed from barren greenstone belts.

scholarly journals Structural Evolution of the Rio das Velhas Greenstone Belt, Quadrilátero Ferrífero, Brazil: Influence of Proterozoic Orogenies on Its Western Archean Gold Deposits

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 983
Author(s):  
Orivaldo Ferreira Baltazar ◽  
Lydia Maria Lobato
Keyword(s):  
Greenstone Belt ◽  
Gold Mineralization ◽  
Structural Evolution ◽  
Shear Zones ◽  
Gold Deposits ◽  
Normal Faults ◽  
Small Scale ◽  
Crenulation Cleavage ◽  
Quadrilátero Ferrífero ◽  
Tectonic Transport

The Quadrilátero Ferrífero region is located in the extreme southeast of the Brasiliano São Francisco craton, Minas Gerais state, Brazil. It is composed of (i) Archean TTG granite-gneaissic terranes; (ii) the Archean Rio das Velhas greenstone belt; (iii) the Proterozoic metasedimentary and metavolcano-sedimentary covers. The Rio das Velhas rocks were deposited in the synformal NW–SE-directed Nova Lima basin. The Archean deformation converted the Nova Lima basin into an ample synclinorium with an eastern inverted flank. Archean orogenic gold mineralization within the Rio das Velhas greenstone belt rocks is controlled by NNW–SSE-directed, Archean regional shear zones subparallel to the strata of the Nova Lima synclinorium borders. Transamazonian and Brasiliano orogenies are superposed onto the Archean structures that control gold mineralization. In the eastern domain, Brasiliano fold-and-fault belts prevail, whereas in the western domain Archean and Transamazonian structures abound. The present study focus mainly is the western domain where the Cuiabá, Morro Velho, Raposos, Lamego and Faria deposits are located. Gold orebodies plunge to the E–NE and are tectonically controlled by the Archean D1–D2 deformation. The D3 Transamazonian compression—Which had a SE–NW vector sub-parallel to the regional mineralized Archean foliation/bedding—Buckled these structures, resulting in commonly open, synformal and antiformal regional folds. These are well documented near the gold deposits, with NE–SW axial traces and fold axes plunging to E–NE. Such folds are normal to inverted, NW-verging, with an axial planar foliation dipping moderately to the SE. The Transamazonian compression has only been responsible for the reorientation of the mineralized Archean gold ores, due to coaxial refolding characterized by an opposite tectonic transport. It has therefore not caused any other significant changes. Thrust shear zones, sub-parallel to the strong Transamazonian foliation, have given rise to localized metric segmentation and to the dislocation of gold orebodies. Throughout the region, along the towns of Nova Lima to Sabará, structures pertaining to the Brasiliano Araçuaí orogeny are represented only by gentle folding and by a discrete, non-pervasive crenulation cleavage. Thrust-shear zones and small-scale normal faults have caused, at most, metric dislocations along N–S-oriented planes.

Chapter 8: The World-Class Gold Deposits in the Geita Greenstone Belt, Northwestern Tanzania

2020 ◽  
pp. 163-183
Author(s):  
P.H.G.M. Dirks ◽  
I. V. Sanislav ◽  
M. R. van Ryt ◽  
J.-M. Huizenga ◽  
T. G. Blenkinsop ◽  
...  
Keyword(s):  
Greenstone Belt ◽  
Gold Mineralization ◽  
Gold Deposits ◽  
Normal Faulting ◽  
Rock Interaction ◽  
Northwestern Tanzania ◽  
The Matrix ◽  
Igneous Activity ◽  
History Of ◽  
Gold Bearing

Abstract The Geita mine is operated by AngloGold Ashanti and currently comprises four gold deposits mined as open pits and underground operations in the Geita greenstone belt, Tanzania. The mine produces ~0.5 Moz of gold a year and has produced ~8.3 Moz since 2000, with current resources estimated at ~6.5 Moz, using a lower cut-off of 0.5 g/t. The geologic history of the Geita greenstone belt involved three tectonic stages: (I) early (2820–2700 Ma) extension (D1) and formation of the greenstone sequence in an oceanic plateau environment; (II) shortening of the greenstone sequence (2700–2660 Ma) involving ductile folding (D2–5) and brittle-ductile shearing (D6), coincident with long-lived igneous activity concentrated in five intrusive centers; and (III) renewed extension (2660–2620 Ma) involving strike-slip and normal faulting (D7–8), basin formation, and potassic magmatism. Major gold deposits in the Geita greenstone belt formed late in the history of the greenstone belt, during D8 normal faulting at ~2640 Ma, and the structural framework, mineral paragenesis, and timing of gold precipitation is essentially the same in all major deposits. Gold is hosted in iron-rich lithologies along contacts between folded metaironstone beds and tonalite-trondhjemite-granodiorite (TTG) intrusions, particularly where the contacts were sheared and fractured during D6–7 faulting. The faults, together with damage zones created along D3 fold hinges and D2–3 hydrothermal breccia zones near intrusions, formed microfracture networks that were reactivated during D8. The fracture networks served as conduits for gold-bearing fluids; i.e., lithologies and structures that trap gold formed early, but gold was introduced late. Fluids carried gold as Au bisulfide complexes and interacted with Fe-rich wall rocks to precipitate gold. Fluid-rock interaction and mineralization were enhanced as a result of D8 extension, and localized hydrofracturing formed high-grade breccia ores. Gold is contained in electrum and gold-bearing tellurides that occur in the matrix and as inclusions in pyrrhotite and pyrite. The gold mineralization is spatially linked to long-lived, near-stationary intrusive centers. Critical factors in forming the deposits include the (syn-D2–6) formation of damage zones in lithologies that enhance gold precipitation (Fe-rich lithologies); late tectonic reactivation of the damage zones during extensional (D8) faulting with the introduction of an S-rich, gold-bearing fluid; and efficient fluid-rock interaction in zones that were structurally well prepared.

Geology and U-Pb geochronology of the Island Lake greenstone belt, northwestern Superior Province, Manitoba

2000 ◽  
Vol 37 (9) ◽  
pp. 1275-1286 ◽  
Author(s):  
Fernando Corfu ◽  
Shoufa Lin
Keyword(s):  
Detrital Zircon ◽  
Greenstone Belt ◽  
Early Time ◽  
Superior Province ◽  
Sedimentary Processes ◽  
Depositional History ◽  
Zircon Population ◽  
History Of ◽  
Greenstone Belts

Mapping and U-Pb geochronology have been used to examine the tectonic and depositional history of the Archean Island Lake greenstone belt in the northwestern Superior Province. The Island Lake greenstone belt comprises two main supracrustal successions, the older Hayes River Group and the younger Island Lake Group. Zircon data for two volcanic units from the Hayes River Group provide identical ages of 2852 ± 1.5 Ma, whereas a turbidite of this group contains a detrital zircon population with ages between 2858 and 2847 Ma. Younger intrusive events include the emplacement of tonalite in the southern batholith at 2825 ± 2 Ma and the Whiteway Island gabbro at 2807 ± 1 Ma. A wacke at the base of the Island Lake Group is dominated by detrital zircon grains yielding ages between 2830 and 2821 Ma, the latter defining a maximum age of sedimentation. A relatively early time of deposition of the lower stratigraphic sections of the Island Lake Group is also supported by an age of 2744 ± 2 Ma obtained for a crosscutting tonalite. By contrast, two turbidite horizons from higher stratigraphic levels of the Island Lake Group contain detrital zircon populations with ages mostly younger than 2730 Ma, the youngest zircon grains providing maximum ages of sedimentation at 2722 and 2712 Ma, respectively. Our results confirm the protracted evolution of the greenstone belt and show in particular that major sedimentary processes were active throughout the main stages of volcanism of the belt. This pattern of protracted sedimentation is comparable to that observed in other greenstone belts of the northwestern Superior Province, all of which developed on pre-Kenoran crust.

scholarly journals The Consciousness of History in Malaysia: The Ideas on Merdeka Day in Sarawak

2018 ◽  
Vol 53 ◽  
pp. 02006
Author(s):  
Muhaimin Sulam ◽  
Norena Abd Karim Zamri ◽  
Ahmad Murad Merican
Keyword(s):  
Stable Condition ◽  
Point Of View ◽  
Small Scale ◽  
Group Discussions ◽  
National History ◽  
Qualitative Approaches ◽  
The People ◽  
Level Of Consciousness ◽  
The Status ◽  
History Of

For decades, the Malaysian national history is in a stable condition and not being challenged by anyone. The enhancement of national history is constantly progress through educational system starting from primary school to university level. The consciousness of national history is the foundation for the unity of the people and country development. Though, from time to time, the status quo starts to face the challenges and disputes which began with small scale and got bigger. This could trigger a national issue. Thus, this study focus on the date of Independence Day amongst Sarawak citizens. As one of the states that form the Federation of Malaysia in 1963, the history of Sarawak as a separate nation with the history of Malaysia has been detected. The consciousness of Merdeka Day for Sarawakian is more to refer to the establishment of the federation rather than the date of August 31, 1957 as the day of independent. To add, this research is to identify the level of consciousness in revising the national history amongst Sarawakian. This study also delves the understanding of “Merdeka” from Sarawakians’ point of view and discuss whether the nation history is proportionate for the Sarawakian. For the methodology, this study applies quantitative and qualitative approaches, a concurrent triangulation mixed method design. The phases of data collection are two including surveys and focus group discussions. Generally, the result shows that the Sarawakian have a new consciousness of the national history. Type of Paper: Empirical

A lavoura dos pobres: Tobacco Farming and the Development of Commercial Agriculture in Bahia, 1870–1930

1999 ◽  
Vol 31 (2) ◽  
pp. 287-329 ◽  
Author(s):  
MICHIEL BAUD ◽  
KEES KOONINGS
Keyword(s):  
Economic History ◽  
Export Market ◽  
Small Scale ◽  
Economic Significance ◽  
Eastern Brazil ◽  
Political Relations ◽  
The Social ◽  
Relative Neglect ◽  
History Of ◽  
Tobacco Cultivation

The social and economic history of North-Eastern Brazil has largely been written as the story of slave-holding plantations. In contrast, this article focuses on the peasant agriculture of tobacco in the state of Bahia. It shows how the small-scale cultivation of tobacco for the European (mainly German) export market had already started well before the end of slavery. Tobacco cultivation gradually expanded to become the most important export product in the first decade of the twentieth century. Apart from its economic significance, the history of Bahian tobacco agriculture throws an interesting light on the social and political relations in the region. Land ownership among the tobacco farmers expanded, but most of them remained locked into ties of dependency to commercial intermediaries and large landowners. On the other hand, the latter's dominant position did not lead to a strong position for tobacco interests in the regional political arena. Finally, the tobacco producers originated in the black (ex-)slave community. This article argues that this specific ethnic make-up played an important role in the organisation of the tobacco sector and its relative neglect by regional and national politicians.

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