
Stewart D. RedwoodIndependent Researcher · Independent
Stewart D. Redwood
BSc(Hons), PhD
Economic geology consultant and research.
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Introduction
Independent, consulting economic geologist
Skills and Expertise
Additional affiliations
September 1982 - September 1986
Publications
Publications (99)
This paper describes the age and geology of 13 centers of Miocene magmatism with related epithermal precious and base metal
mineralization on the eastern side of the northern Altiplano of Bolivia, part of the central Andean polymetallic belt. Twenty-eight
new K-Ar ages are reported, together with a compilation of 12 from the literature. The data sh...
The Soledad Caldera is a low-volume, nonresurgent 'ash flow'-type caldera, located on the Altiplano NW of Oruro in the central Andes of Bolivia. The first stage in the evolution of the composite volcanic field was the intrusion of a cluster of small dacitic stocks around La Joya on the SW edge of the caldera at c.15 Ma. These have related, strong h...
During new excavations at the preceramic rockshelter of Casita de Piedra in western Panama, a cache of 12 unusual stones was recovered near the back wall, dating to between 4800 and 4000 cal bp. The stones include quartz, pyrite, a chalcedony vein nodule, a bladed quartz and jarosite aggregate and a human-modified dacite cylinder. Based on the unus...
Dolphins are widespread in warm oceanic and coastal waters. They habitually frequent islands. In California, Chile, and other localities, prehistoric peoples targeted dolphins. Some communities specialised in their capture. Elsewhere, prehistoric human use of cetaceans is attributed to opportunistic exploitation of active or stranded animals. In Me...
The River Ythan in Aberdeenshire is the only natural inland waterway in northern Scotland. It was navigable for about 10km from Newburgh, the port for Ellon since 1276, to the Meadow of Waterton, the landing place for Ellon. The peak of fluvial traffic was in the late 18th to early 20th centuries during the agricultural improvements for the import...
Editor’s note: The aim of the Geology and Mining series is to introduce early career professionals and students to various aspects of mineral exploration, development, and mining in order to share the experiences and insight of each author on the myriad of topics involved with the mineral industry and the ways in which geoscientists contribute to e...
The Serrania de Tiwanaku is a case study of a long-lived metallogenic history that is unexpected in the young Andean magmatic arc. The one billion year history since the Neoproterozoic, and possibly older since the Paleoproterozoic, is due to basement inliers exposed in the area, which are part of the Proterozoic Arequipa-Antofalla terrane that und...
Cerro Rico de Potosi is the world`s largest Ag deposit (2.7-3.7 Boz Ag) and one of the top five Sn deposits (0.9-1.4 Mt Sn). This talk presents a summary of the first modern comprehensive study of the deposit (Rice et al., submitted 2022). The deposit is hosted by veins and disseminated in a 13.8 Ma rhyodacite dome. The supergiant size is due to di...
Este artículo explora los lugares de producción y refinación de oro de La Española de 1494-1550, la primera fiebre del oro en las Américas (Moya Pons, 2016), y resume estudios históricos y arqueológicos recientes. Existieron tres centros administrativos principales para la extracción de oro, las refinerías de oro en Concepción de la Vega y La Buena...
Editor’s note: The aim of the Geology and Mining series is to introduce early career professionals and students to various aspects of mineral exploration, development, and mining in order to share the experiences and insight of each author on the myriad of topics involved with the mineral industry and the ways in which geoscientists contribute to e...
Editor’s note: The aim of the Geology and Mining series is to introduce early career professionals and students to various aspects of mineral exploration, development, and mining in order to share the experiences and insight of each author on the myriad of topics involved with the mineral industry and the ways in which geoscientists contribute to e...
Book review of "El Hombre que Hablaba con las Piedras: Robert H. Stewart: Expediciones geologicas en Panamá y Bolivia 1947 – 1996" (The Man who Talked with the Stones: Robert H. Stewart: Geological expeditions in Panama and Bolivia 1947 to 1996) by Stanley Heckadon-Moreno. Written in Spanish, this book is about the interesting life and field expedi...
An extensive deposit of agate occurs in Pedro González Island in the Gulf of Panama. Previous archaeological research showed that the agate was exploited between 6200 and 5600 cal BP to make stone tools found at the oldest known Preceramic human settlement in the Pearl Island archipelago. We constrain here the origin and geological context of the a...
Marmato, Colombia, has been an important centre of gold mining since before the first Spanish colonizers arrived in 1536. The Marmato deposit is hosted in a dacite and andesite porphyry stock as sheeted sulphide-rich veinlet systems. The district is currently experiencing a surge in both major mining projects and artisanal mining, driven by sustain...
This article is a book review of the metallogenic map of Central America and the Caribbean with a memoir in Spanish that was published in 2021. The publication is timely given the number of new mineral deposit discoveries in the region in recent years. The map and memoir integrate the mineral deposits with the great advances in understanding the ge...
The Marmato gold deposit is a hybrid between a porphyry gold and a reduced intrusion-hosted gold deposit with epithermal features at shallow levels. It is adjacent to the contemporaneous Aguas Claras porphyry gold deposit. They are located in one of the premier gold-copper belts of Colombia, the Middle Cauca Belt (MCB), and associated with a Late M...
The giant Cobre Panama porphyry Cu-Mo-Au-Ag deposit in western Panama is hosted by an undated andesitic volcanic sequence, the Petaquilla batholith (32.20 ± 0.76–28.28 ± 0.61 Ma), and porphyry stocks (28.96 ± 0.62–27.48 ± 0.68 Ma). Here we present a biostratigraphic age for the volcanic sequence based on stratigraphically diagnostic large foraminif...
The mineral deposits of the Panama microplate are hosted by a composite volcano-plutonic island arc of Late Cretaceous to Quaternary age developed on an oceanic plateau, the Caribbean Large Igneous Province (CLIP), on the western, trailing edge of the Caribbean Plate. Large igneous provinces are formed by gold and chalcophile element-enriched, mant...
The history of mining and exploration in Panama is a case
study of the evolution of mining in a tropical, island arc
environment in the New World from prehistoric to modern
times over a period of ~1900 years. Panama has a strong
mineral endowment of gold (~984 t), and copper (~32
Mt) resulting in a rich mining heritage. The mining history
can be di...
The uninhabited island of Boná in the Gulf of Panama has an unusual industrial history with an abandoned black sand mineral storage lagoon and the wreckage of a ship loading plant and dock that was built by a Japanese company almost fifty years ago. This article describes our investigation of the site and its history. The plant was operated by Hier...
Gold mining was once carried out in the Emperador district that was later part of the Panama Canal Zone but is long since forgotten, and the scant remains are hidden deep in the jungle. The placer and quartz vein gold mines, known as Sardinilla, Quebrada de Oro and Emperador, comprised several small mines in a zone of about 2 km long, based on hist...
Open Access download link:
http://caribjes.com/caribjescurrentissue.html
This paper describes the rise of eustatic sea level in the Gulf of Panama, Panama, and the formation of the Pearl Islands and Taboga archipelagos during the late Pleistocene and Holocene since the end of the last glacial maximum at about 21 ka. The sea level was then about...
Modern mineral exploration for bulk mineable deposits of copper and gold in Colombia has resulted in the discovery of about 2,700 tonnes (t) (87 million ounces / Moz) of gold, 4,820 t (155 Moz) of silver, and 6.88 million tonnes (Mt) (15.2 billion pounds / Blb) of copper. Exploration and discovery has taken place intermittently over the last 50 yea...
El proyecto Antakori (Regulus Resources Inc.) está ubicado a 53 km al noroeste de la ciudad de Cajamarca en el distrito minero de Hualgayoc y es parte de la cuenca de los depósitos de Cu-Au-Ag del Mioceno del norte del Perú. Tiene un recurso indicado de 250 Mt con 0.48% de Cu, 0.29 g/t de Au y 7.5 g/t de Ag y un recurso inferido de 267 Mt con 0.41%...
GEONOTICIAS, Sociedad Dominicana de la Geologia (Dominican Geological Society)
ESPANOL
Loma la Mina, en la Provincia de Sánchez Ramírez, es un sitio importante en la historia de la minería de la República Dominicana por ser la primera mina de cobre en La Española (ahora Hispaniola) y probablemente es la mina de cobre europea más antigua de las Amé...
The origin of the porphyry deposit name has a long and fascinating etymological history of over 3,000 years. Porphyry is derived from the Ancient Greek word porphyra (πορφύρα) or purple. It was originally applied to a rare purple dye, Tyrean purple, extracted by the Phoenicians from murex shells. It was later applied to a prized purple porphyritic...
ABSTRACT The Antakori project (Regulus Resources Inc.) is located 50 km northwest of the city of Cajamarca and is part of the Miocene cluster of Cu-Au-Ag deposits of northern Peru. The mineralization in Antakori is the result of several different hydrothermal systems that overprints each other: (1) a Cu-Au-Ag calcic skarn developed in Cretaceous se...
Este artículo tiene como objetivo principal hacer una revisión del
estado actual de la industria minera dominicana para el año 2018.
En la actualidad el mineral principal de la industria extractiva es el
oro, siendo este el mayor renglón individual de exportación de la
economía dominicana. La República Dominicana produce oro, plata,
cobre, zinc y f...
Formation of the Panama Isthmus, that had global oceanographic and biotic effects in the Neogene, is generally associated with tectonic uplift during collision of the Panama volcanic arc with South America. However, new field, geochemical and geochronological data from the Culebra Cut of the Panama Canal suggest that volcanism also contributed to t...
The Panama-Chocó Arc is a composite volcano-plutonic island arc of Late Cretaceous to Miocene age developed on ocean crust of the Caribbean large igneous province (CLIP) on the western or trailing edge of the Caribbean Plate. An early arc of Late Cretaceous to Eocene age developed by northerly or north-easterly subduction of the Farallon Plate to f...
This article reviews and summarises two books which have recently been published in Spanish about the mining history of the Dominican Republic, the most important mining country in the Caribbean, where the first European gold mining in the New World started in 1494, and host to the giant Pueblo Viejo gold deposit.
John Stuart, the Third Earl of Bute (1713-1792) and one-time Prime Minister of Great Britain, amassed one of the largest mineral collections of the time in the 1760s to 1780s. Indeed, it was one of the largest private mineral collections ever made, and surpassed those of all but the very largest museums even today. Unfortunately, the great collecti...
This is an obituary and biography of Charles (Scottie) Bruce (1931-2017), a Scottish mining geologist who spent most of his career in Bolivia and will be remembered for his contributions to the Bolivian mining industry. In English and Spanish.
Fossil plants in the Miocene Caracoles Tuff at the giant Cerro Rico silver-tin deposit in Potosi, Bolivia, are altered to coaly bitumen which is unusual for two reasons, 1) plant material in hydrothermal systems is usually silicified, and 2) coal has formed without sedimentary compaction due solely to heat. The question in this on-going research is...
The Marmato (Colombia) and Kori Kollo (Bolivia) gold deposits are described and compared. The Marmato system has three main components: 1) the Upper Zone of massive sulphide veins of Au-Ag-Zn of intermediate sulphidation state, called epithermal veins, with extensive historical and active vein mining, which has been explored for the potential to be...
The Marmato epithermal to mesothermal gold deposit is located in the late Miocene Middle Cauca Gold Belt in the Western Cordillera of the northern Andes. Mineralization is hosted by the Marmato composite porphyry intrusion, with an adakite-like signature, dated between 6.576 ± 0.075 Ma and 5.75 ± 0.11 Ma by LA-ICP-MS 206 Pb/ 238 U zircon, and the A...
The Marmato epithermal to mesothermal vein gold deposit is located in the late Miocene Middle Cauca Gold Belt in the Western Cordillera of the northern Andes. Exploration work by Gran Colombia Gold Corp. has defined total underground resources in the Upper and Deeps Zones in the measured, indicated and inferred categories (NI 43-101) of 93.2 Mt con...
The field trip will visit the famous Cerro Rico of Potosi, the largest silver deposit in the world with a total silver endowment (production + resources) estimated to be in excess of 117,000 tonnes (3.7 billion ounces) of silver, as well as significant amounts of tin (>820,000 tonnes) and zinc. The Cerro Rico is so important that it features on the...
English version of the GeoNoticias article.
This article is a review of the current state of the Dominican mining industry in 2017 and first quarter of 2018. Minerals, principally gold, are now the largest single export sector of the Dominican economy. The Dominican Republic produces gold, silver, copper, zinc and ferronickel from three mines. Fer...
Este artículo es una revisión del estado actual de la industria minera dominicana en 2017 y primer trimestre del 2018. Los minerales, principalmente el oro, son ahora el sector exportador individual más grande de la economía dominicana. La República Dominicana produce oro, plata, cobre, zinc y ferroníquel de tres minas. Las exportaciones de ferroní...
This article describes the most northerly record of a southern elephant seal (Mirounga leonina) in the Pacific Ocean on 31 December 2016 in the Gulf of Panama, Panama (08°47’40” N, 70°33’17” W). A large specimen ~2.5 m long was observed and photographed resting on the beach at the Island of Taboga and later in the day on the nearby Island of Melone...
El depósito de oro de Marmato se encuentra localizado en uno de las principales provincias metalogenéticas de Colombia, el cinturón del Cauca Medio. Marmato se compone de cinco intrusiones porfiríticas de composición andesitica a dacitica las cuales muestran una firma " similar a las adakitas " , calcio-alcalinas a calcio-alcalinas de alto potasio,...
Spectral data analysis via hyperspectral core imaging technology is a robust tool for identifying and mapping alteration minerals in a number of different deposit styles and terrains. Recent results from the AntaKori Cu-Au-Ag project in the Hualgayoc district, northern Peru, have shown that reflectance imaging spectroscopy has been particularly hel...
The AntaKori Project, located in the Hualgayoc mining district, has a NI 43-101 compliant inferred sulphide mineral resource of 295 Mt @ 0.36 g/t Au, 0.48 % Cu and 10 g/t Ag (Wilson, 2012) which is still open in all directions. It is a calcic copper-gold-silver skarn. Mineralization is principally hosted in prograde and retrograde exoskarn in the C...
Este artículo es una revisión del estado actual de la industria minera dominicana y abarca eventos de los últimos dos años, 2015 y 2016. La minería fue el sector de más rápido crecimiento de la economía dominicana en este período, a pesar de los bajos precios de los metales. La República Dominicana produce oro, plata, cobre, zinc, ferroníquel y bau...
The varied and accessible geology of Bute continues to generate considerable interest for geological research. This article is a review of new geological research published since the previous update (Redwood, 2012). New geological mapping and descriptions have been published on the Dalradian schists, the Bute Ophiolite, and the Carboniferous sedime...
A little known facet of John Stuart, 3rd Earl of Bute (1713-1792), is that he was an avid mineral collector with one of the biggest mineral collections of the day, and was interested in geology (Figure 1). He succeeded to the Earldom of Bute when he was ten years old in 1723. The tutor of the future King George III (1738-1820) and later his Prime M...
Resumen
Entre los años 2007 y 2010 se desarrollaron reconocimientos pedestres acompañados de sondeos y pequeñas excavaciones en el Archipiélago de Las Perlas, Panamá. Las investigaciones más intensivas se realizaron en Isla Pedro González. Esta breve síntesis preliminar de la cronología de la ocupación prehispánica de esta isla se basa en datacione...
This talk describes the distribution of copper and gold deposits in Panama in the context of their availability for pre-Columbian mining and the distribution of archaeological artifacts. Panama has a rich endowment of gold and copper deposits. Despite the paucity of evidence for pre-Columbian mining in Panama, which would have been shallow and ephe...
This paper presents a geological model for the San Cristobal silver-zinc-lead deposit, Department of Potosi, Bolivia. San Cristobal is the largest zinc deposit in Bolivia and the second largest silver deposit. The deposit is an intermediate sulfidation epithermal deposit of Ag-Zn-Pb, and has a well preserved steam-heated opal cap underlain by kaoli...
The Marmato gold deposit occurs in the Late Miocene, Middle Cauca gold belt, in the Western Cordillera of Colombia, 80 km south of Medellin. Open pit resources are estimated at 12.4 Moz Au and 75 Moz Ag with grades of 1.1 g/t Au and 5.1 g/t Ag. Past production is 2.3 Moz Au over five centuries. Marmato lies within the Romeral Terrane, an oceanic te...
Affinity between bismuth and gold in the Marmato gold deposit, Colombia: a probable case of the liquid bismuth collector model.
A lthough Panama has traditionally been a strong service-based economy, fuelled principally by the Panama Canal, among other things, the country is fast emerging as a mining player with one gold mine in operation, a major copper mine under construction and two other gold deposits at the development stage. Panama's economy has the strongest gross do...
Background Marmato, Colombia has been an important centre of gold mining since before the first Spanish colonisers arrived in 1536 (Redwood, 2011). The district is currently experiencing a surge in both major mining projects and artisanal mining (Figure 1), driven by the high price of gold. Ore from small scale and artisanal mines is processed in n...
Transactions of the Buteshire Natural History Society
The Island of Bute has Scotland’s geology in miniature, with the metamorphic rocks of the Highlands in the north and the sedimentary and volcanic rocks of the Midland Valley in the south part, separated by the Highland Boundary Fault which runs right through the island from Rothesay to Scalpsie...
The metallogenesis of Colombia-Panama is placed in the context of new tectonic models with
relative eastward motion of Pacific-derived Caribbean oceanic lithosphere during the Cenozoic
due to westward drift of the American plates, accretion of oceanic and island arc terranes to the
NW margin of South America since the Cretaceous, and development of...
Transactions of the Buteshire Natural History Society
This short paper reports an overlooked historical description of gold occurrences in the Dalradian made in about 1870 on the Island of Bute, Scotland and describes their geological context. These gold occurrences, absent from the geological literature until now, are within the Dalradian gold bel...
This talk will examine the metallogenic evolution of the Eastern Cordillera of the Bolivian Andes, one of the world's greatest mineral provinces. While metallogenic belts are commonly defined for a single metal in a single geological event over a short period of time, the Eastern Cordillera has multiple metallogenic events for several metals, inclu...
The Marmato gold deposit is located in the Western Cordillera of Colombia, 80 km south of Medellin. It lies in the Middle Cauca Gold Belt of Late Miocene age, which is characterized by intermediate sulfidation epithermal gold deposits, such as Marmato, and porphyry gold deposits such as La Colosa. Underground mining has been carried out for more th...
The Marmato gold deposit is located in the Western Cordillera of Colombia, 80 km south of Medellin. It lies in the Middle Cauca Gold Belt of Late Miocene age, which is characterized by intermediate sulfidation epithermal gold deposits, such as Marmato, and porphyry gold deposits such as La Colosa. Underground mining has been carried out for more th...
Inlice is a new high-sulphidation epithermal gold prospect in the Erenler Dağı Volcanic Belt in western Anatolia, Turkey, in an area with no previously known gold. Mineralization is associated with vuggy and sugary quartz in steeply dipping, structurally controlled silica ledges which cut an andesitic volcanic dome. The main Ana Ledge has an averag...
Field observations in the Pueblo Viejo district, Dominican Republic, show that an extensive advanced argillic
lithocap and the contained giant high-sulfidation epithermal gold-silver deposit were emplaced beneath a thick limestone cover. Massive silicification and associated magnetite and hematite, containing the same anomalous multielement suite a...
Grass-roots exploration is an effective way to discover new mineral resources and, indeed,
precedes brownfields exploration. About 2,500 metric tons (t; 80 Moz) of gold needs to be discovered
every year to replace reserves after production. The lack of exploration and discoveries in recent years has
become very apparent in the current bull market....
In this paper we investigate the management of the mineral exploration business, focusing on precious and base metal exploration. We define exploration and discovery (E&D) as the research and development (R&D) of the mining industry, and draw comparisons from R&D in other industries. We stress the need for innovation and leadership among exploratio...
A variety of metals and deposit types define the metallogeny of the Andes from Colombia through Ecuador, Peru, and Bolivia to Argentina and Chile, although porphyry copper and epithermal gold deposits undoubtedly predominate and will continue to do so. Discoveries over the last 30 yrs or so, predominantly in the central Andes and especially Chile,...
Antamina, the world’s largest copper-zinc skarn deposit, entered production in 2001. This paper describes
the development of the geologic model for the feasibility study (1996–1998). Antamina is located in the eastern
part of the Western Cordillera of northern Peru at latitude 9º 32' S and longitude 77º 03' W and 4,200 to
4,800 m in elevation.
Anta...
The Pacajake mine, hidden high in the Cordillera Oriental of the Bolivian Andes, is famous for its rare selenides, selenates and selenites, and is the type locality for penroseite, ahlfeldite, olsacherite and mandarinoite. It was recently rediscovered after having stood abandoned for more than 60 years, and some new specimen material was collected,...
Bolivia is fortunate to have had the lifetime services of the renowned and distinguished geologist Friedrich (Federico) Ahlfeld, respected as "The Father of Bolivian Geology." In a career of over fifty years in mining geology in his adopted country of Bolivia, he published numerous works on the geology and mineral deposits of Bolivia, many of which...
The stratigraphical and structural continuity of the Late Proterozoic Dalradian rocks of the Scottish Highlands is re-examined in the light of new U–Pb zircon ages on the tuffs belonging to the Tayvallich Volcanic Formation (601 ± 4 Ma), and on the late Grampian ‘Newer Gabbros’ (470 ± 9 Ma) of Insch and Morven–Cabrach in Aberdeenshire. These age da...
Geological map of Portsoy, Sheet 96W.
Geological map at 1:50,000 scale, Huntly, Sheet 86W.
Antamina, the world’s largest known skarn deposit of copper and zinc, is located in the eastern part of the Western Cordillera of north Peru at 9° 32’ south and 77° 03’ west, at an altitude between 4,200 and 4,800 meters. The terrain comprises steep limestone peaks, glacial valleys and lakes, and deep canyons.
This paper describes the geology and...
Abstract - The Kori Kollo gold deposit is hosted by a c.15 Ma sericitized dacite stock in the La Joya district on the Bolivian Altiplano. The mineralization is of the Bolivian polymetallic vein (BPV) type, with a significant amount of the gold reserves contained in the oxide cap.
Field and microscopic studies, K-Ar dating, δ34S values of pyrite, a...
Miocene (16.4 to 7.4 Ma) basic to intermediate shoshonitic lavas and intrusives are located in the inner arc of the Central Andes in Bolivia and were erupted from major fissures in an active thrust belt during are broadening. They are spatially and temporally linked with intermediate to felsic volcanic and intrusive rocks of the High K calc-alkalin...
The high T/low P Buchan-style metamorphism of the NE Grampians is texturally associated with the local D2 deformation of the Dalradian. It has previously been suggested that the high geothermal gradients necessary to produce such metamorphic conditions were related to a high heat flow environment which culminated in the intrusion of the voluminous...
La mineralización de oro - polimetalico en Ubina (SW Bolivia) se presenta en un sistema hidrotermal grande relacionado a un intrusivo. Las estructuras forman vetas y han canalizado los fluidos para formar mantos que reemplazan rocas calcáreas. La intrusión y la mineralización han side controladas por una zona de cizallamiento siniestral que tiene u...
Synopsis
The Chapare Group inlier in the Interandean zone of the eastern Andes of Bolivia is described. It is interpreted
as a sequence that includes Lake Superior-type banded iron formations with associated crocidolite and
magnesite, which have been mined on a small scale. The stratigraphy of the Chapare Group conforms with
the types of sequence t...
This report describes reconnaissance mineral exploration in Neoproterozoic Dalradian metasediments and Caledonian granites in the central Highlands of Scotland. The results include the discovery of new gold occurrences (S. Redwood).
Many new and significant gold occurrences have been discovered in Scotland as a result of recent exploration and research by the BGS, mining companies and universities.
Published in Terra Abstracts
Many new and significant gold occurrences have been recognised in Scotland as a result of recent exploration and research. Free gold occurs in Besshi-type stratiform sulphide deposits in 2.4-2.0 By metamorphics, in podiform chromitite in Lower Palaeozoic ophiolite, and in deeply weathered Caledonian migmatite; a small...
Field mapping and compilation of extensive commercial and academic work is currently being undertaken by BGS to produce a new map and reinterpretation of the synonogenic Caledonian mafic-ultramafic intrusion between Huntly and Knock. This is not a simple. layered intrusion, but contains a number of discrete cumulate bodies, some of which are well l...
South American Explorer
This article describes the geology of the largest salt lake in the world, the Salar de Uyuni in southern Bolivia. It contains the largest resource of lithium in the world, as well as significant resources of halite, potash, boron and magnesium.
Thousands of prospectors are heading for the Amazon jungles in search of gold. Tipuani in northern Bolivia with its rich gold fields is the goal for many. The article described the placer and palaeoplacer gold deposits.
The metallogenic belts of the Central Andes (iron, porphyry copper, polymetallic and tin) are genetically related to an eastward migrating magmatic arc. The polymetallic belt of the Bolivian Altiplano formed during Miocene arc broadening and lies in a critical position for understanding the genesis of this zonation. -Author
South American Explorer
This article describes the present-day gold-rush in the foothills of the Bolivian Andes at Tipuani.