Postwildfire Landscape Identity in Mediterranean Ecosystems: Three Study Cases from the Coastal Range of Central Chile

AbstractK-Ar isotopic dating of very low-grade metamorphism affecting Triassic-Jurassic rocks in the Coastal Range of central Chile was carried out on whole rocks and their <2 mm size fractions. In the study area, a regional-burial low-grade metamorphism at anchizone conditions (T≤190°C) and low-pressure conditions (P≥1.3 kbar) has been described. The highest observed temperatures are related to a contact metamorphism produced by nearby Jurassic intrusions, with aP-Testimate at the immediate contact zone of ~650–690°C and 4 kbar.The whole-rock K-Ar age of 174±5 Ma is interpreted as belonging to the contact metamorphism due to the intrusion of Jurassic plutons (165±5 Ma to 175±5 Ma). A time-interval of ~20 Ma between the diagenesis (206 Ma) and the anchizonal very low-grade metamorphism (181–184 Ma) is obtained, and a rate of subsidence of ~120 m/Ma is proposed for these Triassic-Jurassic basins. A thermal influence on the burial, very low-grade, regional metamorphism is invoked.

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AN ANALYSIS OF WILDFIRE RISK AND HISTORICAL OCCURRENCE FOR A MEDITERRANEAN BIOSPHERE RESERVE, CENTRAL CHILE

Journal of Environmental Engineering and Landscape Management ◽

10.3846/16486897.2017.1374280 ◽

2018 ◽

Vol 26 (2) ◽

pp. 128-140 ◽

Cited By ~ 1

Author(s):

Camila Bańales-Seguel ◽

Francisco De La Barrera ◽

Alejandro Salazar

Keyword(s):

Biosphere Reserve ◽

Mediterranean Ecosystems ◽

Historical Records ◽

Gis Analysis ◽

Central Chile ◽

Wildfire Risk ◽

Wildfire Occurrence ◽

Future Events ◽

Landsat Satellite ◽

Very High

Wildfires are one of the main processes that currently shape Mediterranean ecosystems. The analysis of wildfire risk combined with historical records allows for a greater understanding of trends and their relation to territorial variables that are favourable to future events. Using GIS analysis, we assess wildfire risk in La Campana – Peñuelas Biosphere Reserve, in Central Chile. Additionally, with official historical records and LANDSAT satellite images from 1985–2015 and GIS we determine historical occurrence in the Reserve. We found that the areas with very high risk of wildfire occurrence have a strong combination of ignition factors such as presence of human settlements and road connectivity, and variables that would be negatively impacted by the occurrence of wildfires, such as degraded soils and vulnerable vegetation. These findings highlight the need to destine resources to fire prevention in these areas and develop adaptation strategies for risk management at different scales.

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Nature and P-T-t constraints of very low-grade metamorphism in the Triassic-Jurassic basins, Coastal Range, central Chile

Revista geológica de Chile ◽

10.4067/s0716-02082005000200002 ◽

2005 ◽

Vol 32 (2) ◽

Cited By ~ 2

Author(s):

Mauricio Belmar ◽

Diego Morata

Keyword(s):

Low Grade ◽

Central Chile ◽

Grade Metamorphism ◽

Coastal Range

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Microstructures and interlayering in pyrophyllite from the Coastal Range of central Chile: evidence of a disequilibrium assemblage

Clay Minerals ◽

10.1180/0009855043940146 ◽

2004 ◽

Vol 39 (4) ◽

pp. 439-452 ◽

Cited By ~ 2

Author(s):

M. D. Ruiz Cruz ◽

D. Morata ◽

E. Puga ◽

L. Aguirre ◽

M. Vergara

Keyword(s):

Electron Microscopy ◽

Mineral Assemblage ◽

Analytical Electron Microscopy ◽

Orientation Relationships ◽

Central Chile ◽

Analytical Electron ◽

Two Generations ◽

Sedimentary Formation ◽

Weathering Process ◽

Coastal Range

AbstractPyrophyllite from a Triassic sedimentary formation from the Coastal Range of Chile has been investigated by transmission/analytical electron microscopy (TEM/AEM). The mineral assemblage includes pyrophyllite, muscovite, paragonite, a kaolin mineral, boehmite, rutile and hematite. The textures indicate that the protolith was a volcanoclastic rock. Petrographic evidence, chemistry, and the mineral assemblage suggest the intense leaching of the parent rock by a weathering process, before the metamorphic episode, to create the protolith for the pyrophyllite. Pyrophyllite always grows from the kaolin mineral, and both phases show close orientation relationships. The presence of parallel intergrowths of pyrophyllite and muscovite indicate that muscovite also grew from the kaolin mineral. Nevertheless, the composition of muscovite suggests that this phase must also form from another precursor, probably Al smectite. The AEM data and textural relationships between pyrophyllite and muscovite reveal the presence of two generations of muscovite and suggest that Na-rich muscovite recrystallized into a Na-free muscovite and paragonite.

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