Eruptive history and petrochemistry of the Bulusan volcanic complex: Implications for the hydrothermal system and volcanic hazards of Mt. Bulusan, Philippines

Geothermics ◽  
1993 ◽  
Vol 22 (5-6) ◽  
pp. 417-434 ◽  
Author(s):  
Francisco G. Delfin ◽  
Conrado C. Panem ◽  
Marc J. Defant
2021 ◽  
Vol 173 ◽  
pp. 103951
Author(s):  
Geoffrey Mibei ◽  
Björn S. Harðarson ◽  
Hjalti Franzson ◽  
Eniko Bali ◽  
Halldór Geirsson ◽  
...  

2017 ◽  
Vol 36 (2) ◽  
pp. 197-244 ◽  
Author(s):  
Laura C. Walkup ◽  
Thomas J. Casadevall ◽  
Vincent L. Santucci

ABSTRACT Geologic features, particularly volcanic features, have been protected by the National Park Service since its inception. Some volcanic areas were nationally protected even before the National Park Service was established. The first national park, Yellowstone National Park, is one of the most widely known geothermal and volcanic areas in the world. It contains the largest volcanic complex in North America and has experienced three eruptions which rate among the largest eruptions known to have occurred on Earth. Half of the twelve areas established as national parks before the 1916 Organic Act which created the National Park Service are centered on volcanic features. The National Park Service now manages lands that contain nearly every conceivable volcanic resource, with at least seventy-six managed lands that contain volcanoes or volcanic rocks. Given that so many lands managed by the National Park Service contain volcanoes and volcanic rocks, we cannot give an overview of the history of each one; rather we highlight four notable examples of parks that were established on account of their volcanic landscapes. These parks all helped to encourage the creation and success of the National Park Service by inspiring the imagination of the public. In addition to preserving and providing access to the nation's volcanic heritage, volcanic national parks are magnificent places to study and understand volcanoes and volcanic landscapes in general. Scientists from around the world study volcanic hazards, volcanic history, and the inner working of the Earth within U.S. national parks. Volcanic landscapes and associated biomes that have been relatively unchanged by human and economic activities provide unique natural laboratories for understanding how volcanoes work, how we might predict eruptions and hazards, and how these volcanoes affect surrounding watersheds, flora, fauna, atmosphere, and populated areas.


1987 ◽  
Vol 31 (1-2) ◽  
pp. 99-113 ◽  
Author(s):  
Claude Robin ◽  
Philippe Mossand ◽  
Guy Camus ◽  
Jean-Marie Cantagrel ◽  
Alain Gourgaud ◽  
...  

2008 ◽  
Vol 120 (5-6) ◽  
pp. 599-618 ◽  
Author(s):  
B. S. Singer ◽  
B. R. Jicha ◽  
M. A. Harper ◽  
J. A. Naranjo ◽  
L. E. Lara ◽  
...  

2022 ◽  
Vol 117 (1) ◽  
pp. 25-55
Author(s):  
Stephanie Lohmeier ◽  
Bernd Lehmann ◽  
Albrecht Schneider ◽  
Andrew Hodgkin ◽  
Raymond Burgess

Abstract The El Volcán gold project (8.9 Moz Au @ 0.71 g/t Au) is located in the Maricunga gold belt in northern Chile, on the flank of the large Cenozoic Copiapó Volcanic Complex. Precious metal mineralization is hosted in two zones (Dorado and Ojo de Agua) of (pervasively) altered Miocene porphyry intrusions and lava flows of andesitic to rhyolitic composition, and in breccias. The ore zones reflect an evolving magmatic-hydrothermal system with mineral assemblages of magnetite-ilmenite-pyrite-molybdenite (early), bornite-chalcopyrite-pyrite-rutile (stage I), chalcocite-chalcopyrite-enargite-fahlore-pyrite (stage II), and chalcopyrite-covellite-pyrite (stage III). Alteration is dominantly of Maricunga-style (illite-smectite-chlorite ± kaolinite), partly obscured by quartz-kaolinite-alunite ± illite ± smectite alteration. Powdery quartz-alunite-kaolinite alteration with native sulfur and cinnabar forms shallow steam-heated zones. Early K-feldspar ± biotite alteration is preserved only in small porphyry cores and in deep drill holes. Most gold is submicrometer size and is in banded quartz veinlets, which are characteristic of the Maricunga gold belt. However, some gold is disseminated in zones of pervasive quartz-kaolinite-alunite alteration, with and without banded quartz veinlets. Minor visible gold is related to disseminated chalcocite-chalcopyrite-enargite-fahlore-pyrite. The lithogeochemical database identifies a pronounced Au-Te-Re signature (>100× bulk crust) of the hydrothermal system. Molybdenum-rich bulk rock (100–400 ppm Mo) has an Re-Os age of 10.94 ± 0.17 Ma (2σ). 40Ar-39Ar ages on deep K-feldspar alteration and on alunite altered rock have the same age within error and yield a combined age of 11.20 ± 0.25 Ma (2σ). The formation of the El Volcán gold deposit took place during the establishment of the Chilean flat-slab setting in a time of increasing crustal thickness when hydrous magmas were formed in a mature arc setting. The vigorous nature of the hydrothermal system is expressed by abundant one-phase vapor fluid inclusions recording magmatic vapor streaming through a large rock column with a vertical extent of ≥1,500 m.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anna Jentsch ◽  
Walter Duesing ◽  
Egbert Jolie ◽  
Martin Zimmer

AbstractCarbon dioxide is the most abundant, non-condensable gas in volcanic systems, released into the atmosphere through either diffuse or advective fluid flow. The emission of substantial amounts of CO2 at Earth’s surface is not only controlled by volcanic plumes during periods of eruptive activity or fumaroles, but also by soil degassing along permeable structures in the subsurface. Monitoring of these processes is of utmost importance for volcanic hazard analyses, and is also relevant for managing geothermal resources. Fluid-bearing faults are key elements of economic value for geothermal power generation. Here, we describe for the first time how sensitively and quickly natural gas emissions react to changes within a deep hydrothermal system due to geothermal fluid reinjection. For this purpose, we deployed an automated, multi-chamber CO2 flux monitoring system within the damage zone of a deep-rooted major normal fault in the Los Humeros Volcanic Complex (LHVC) in Mexico and recorded data over a period of five months. After removing the atmospheric effects on variations in CO2 flux, we calculated correlation coefficients between residual CO2 emissions and reinjection rates, identifying an inverse correlation of ρ = − 0.51 to − 0.66. Our results indicate that gas emissions respond to changes in reinjection rates within 24 h, proving an active hydraulic communication between the hydrothermal system and Earth’s surface. This finding is a promising indication not only for geothermal reservoir monitoring but also for advanced long-term volcanic risk analysis. Response times allow for estimation of fluid migration velocities, which is a key constraint for conceptual and numerical modelling of fluid flow in fracture-dominated systems.


2020 ◽  
Author(s):  
Xiaolong Zhou ◽  
Klaudia Kuiper ◽  
Jan Wijbrans ◽  
Katharina Boehm ◽  
Pieter Vroon

Abstract. High-resolution geochronology is essential to determine the growth-rate of volcanoes, which is one of the key factors to establish the periodicity of explosive volcanic eruptions. However, there are less high-resolution eruptive histories (> 106 years) determined for long-lived submarine arc volcanic complexes than for subaerial complexes, since the submarine volcanoes are far more difficult to observe than subaerial ones. In this study, high-resolution geochronology and major element data are presented for Milos Volcanic Field (VF) in the South Aegean Volcanic Arc, Greece. The Milos VF has been active for over 3 Myrs, and the first two million years of its eruptive history occurred in a submarine setting that has emerged above sea level nowadays. The long submarine volcanic history of the Milos VF makes it an excellent natural laboratory to study the growth-rate of a long-lived submarine arc volcanic complex. This study reports twenty-one new high-precision 40Ar/39Ar ages and major element compositions for eleven volcanic units of the Milos VF. This allows us to refine the volcanic evolution of Milos into nine phases and five volcanic quiescence periods of longer than 200 kyrs, on the basis of age, composition, volcano type and location. Phase 1–5 (~ 3.34–1.60 Ma) contributed ~ 85 % by volume to the Milos VF, whereas the volcanoes of Phase 6–9 only erupted small volumes (2–6 km3 in DRE) rhyolitic magmas. Although there are exceptions of the felsic cone volcanoes of Phase 1–2, in general the Milos VF becomes more rhyolitic in composition from Phase 1 to Phase 9. In particular, the last three phases (Phase 7–9) only contain rhyolites. Moreover, the high-resolution geochronology suggests that there are at least three periods of different long term volumetric volcanic output rate (Qe). In the Milos VF, the Qe varies between 0.2 and 6.6 × 10−5 km3 yr−1, 2–3 orders of magnitude lower than the average for rhyolitic systems and continental arcs.


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