Effusive silicic volcanism in the Paraná Magmatic Province, South Brazil: Evidence for locally-fed lava flows and domes from detailed field work

Polo, Liza Angélica; Janasi, Valdecir de Assis; Giordano, Daniele; Lima, Evandro Fernandes de; Cañón‐Tapia, Edgardo; Roverato, Matteo

doi:10.1016/j.jvolgeores.2017.08.007

Cited by 28 publications

(13 citation statements)

References 43 publications

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“…Lava characterization is usually conducted by analyzing geochemistry data and petrography [7][8][9][10][11][12]. However, these methods cannot be used to accurately characterize lava in all cases, such as for the Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Rock Magnetic, Petrography, and Geochemistry Studies of Lava at the Ijen Volcanic Complex (IVC), Banyuwangi, East Java, Indonesia

et al. 2018

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Lava has complex geochemical characteristics based on differences in eruption centers, eruptive events, and flow emplacement. Characterization of lava is useful for understanding the geological conditions of a volcanic region. To complement geochemical methods, rock magnetic methods are being used to analyze lava. To explore the potential uses of rock magnetic methods for lava characterization, a series of magnetic measurements were completed in lava samples from eight locations in the Ijen Volcanic Complex (IVC) in Banyuwangi, East Java, Indonesia. These locations were grouped into two eruption centers: Ijen Crater and Mount Anyar. The magnetic measurements included frequency-dependent magnetic susceptibility, thermomagnetic, anhysteretic remanent magnetization (ARM), isothermal remanent magnetization (IRM), and hysteresis curve analyses. These measurements were supplemented using X-ray fluorescence, petrography analyses, and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS). Based on their lithology, lava samples were categorized into basalt, basaltic andesite, and basaltic trachyandesite. The dominant magnetic mineral contained in the sample was iron-rich titanomagnetite and titanium-rich titanomagnetite with a magnetic pseudo-single-domain and small amounts of superparamagnetic grain minerals in some samples. The significant difference in mass specific susceptibility (χ LF ) is caused by differences in the crystallization process. The differences in susceptibility frequency dependence (χ FD ) highlighted the differences in the magma cooling rate, demonstrated by the differences in the percentage of opaque mineral groundmass. The rock magnetic method was proven to support the geochemistry and petrography methods used to characterize lava and identify the causes of differences in lava characteristics.

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Section: Introductionmentioning

confidence: 99%

Rock Magnetic, Petrography, and Geochemistry Studies of Lava at the Ijen Volcanic Complex (IVC), Banyuwangi, East Java, Indonesia

et al. 2018

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“…Waichel et al (2012) suggest that many conduits were required to generate the lava dome-field of Palmas-type described in the Torres Syncline region. Additionally, Polo et al (2018b) propose that the numerous dome structures in Palmas-type rocks indicate that lava feeding took place just below these units. In the study area, lateral gradation from P through Raf to Rd, associated with the vertical planar disjunctions ( Fig.…”

Section: Discussionmentioning

confidence: 95%

“…Luchetti et al (2018b) indicated a pyroclastic origin for Palmas-type rocks that occur in central parts of the PIP (including those described in southwestern Paraná State), characterizing them as high-grade ignimbrites. Polo et al (2018b), in turn, describe several structures indicative of effusive origin for Palmas volcanites that outcrop in the Gramado Xavier region, Rio Grande do Sul: lava domes, lobed flows, tabular flows, and basal autobreccias. All these structures are also observed in the Palmas plateau.…”

Section: Discussionmentioning

confidence: 98%

“…Although amygdales are only occasionally present in most lithofacies, in Ram and Ral they account for up to 35% of the total rock volume. In these cases, the amygdales are generally flattened parallel to the planar disjunction and aligned parallel to the flow direction (e.g., Polo et al 2018b, Benites et al 2020. Ram amygdales are mostly filled with chalcedony, while in intensely altered Ral, they are filled with clay materials ( Fig.…”

Section: Local Geology and Facies Characterizationmentioning

confidence: 99%

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Facies architecture and volcanological aspects of silicic rocks from the Palmas plateau, Brazil

2020

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The nature of the extensive silicic units of the Paraná Igneous Province is still heavily debated. The silicic rocks that outcrop in the Palmas plateau (Southwestern Parana State) show aphyric texture and TiO 2 < 0.86%, being classified as Palmas-type rhyolites. Physical volcanology criteria are used here to constrain their origin. Textural and structural variations are observed in these rocks, resulting in the description of nine lithofacies: pitchstone; banded vitreous rhyolite; aphanitic rhyolite; rhyolite with planar disjunctions; massive rhyolite; compositionally banded rhyolite; amygdaloid rhyolite, rhyolite with quartz levels, and altered rhyolite. Folded compositional banding associated with volcanic conduits, well-defined lobes and basal autobreccias attest to an effusive origin for most lithofacies. They occur as domes or extensive tabular bodies, fed by volcanic conduits. For both domes and tabular units, the faciological sequence involves (from bottom to top): altered rhyolite; aphanitic rhyolite or rhyolite with tightly-spaced planar disjunctions; monotonous rhyolite with decimetric-spaced planar disjunctions; and top portions with fast cooling features. Only banded vitreous rhyolite differs due to the presence of shards and gas-escape pipes, aspects that imply in a pyroclastic nature. Therefore, a secondary pyroclastic flow created by lava collapse is suggested as its origin, although further studies are required.

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“…Caxias do Sul dacite displays a glomeroporphyritic to cumulophyric texture, characterized by clusters of euhedral plagioclase phenocrysts (An 52-67 ; Polo et al, 2018) set in a partially devitrified dark brown glassy matrix ( Fig. S3E).…”

Section: Caxias Do Sul Dacite (Sample Xg-13)mentioning

confidence: 99%

Supplemental Material: Rapid eruption of silicic magmas from the Paraná magmatic province (Brazil) did not trigger the Valanginian event

Rocha¹,

al.²

2020

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Effusive silicic volcanism in the Paraná Magmatic Province, South Brazil: Evidence for locally-fed lava flows and domes from detailed field work

Cited by 28 publications

References 43 publications

Rock Magnetic, Petrography, and Geochemistry Studies of Lava at the Ijen Volcanic Complex (IVC), Banyuwangi, East Java, Indonesia

Rock Magnetic, Petrography, and Geochemistry Studies of Lava at the Ijen Volcanic Complex (IVC), Banyuwangi, East Java, Indonesia

Facies architecture and volcanological aspects of silicic rocks from the Palmas plateau, Brazil

Supplemental Material: Rapid eruption of silicic magmas from the Paraná magmatic province (Brazil) did not trigger the Valanginian event

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