Paleomagnetic and AMS studies of the El Castillo ignimbrite, central-east Mexico: Source and rock magnetic nature

Alva‐Valdivia, Luis M.; Agarwal, Amar; Caballero-Miranda, C. I.; Garcia-Amador, B. I.; Morales-Barrera, W.; Rodríguez-Elizarraráz, S.; Rodríguez-Trejo, A.

doi:10.1016/j.jvolgeores.2017.02.014

Cited by 19 publications

(11 citation statements)

References 44 publications

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“…The predominance of imbricated oblate fabrics in our samples suggests a sedimentary-related fabric as the main fabric recorded in the RBI, resulting from the deposition and alignment of inequant ferromagnetic particles in the PDC (Cañón-Tapia and Mendoza-Borunda, 2014). Similar to granular flow in sedimentary systems, the K in sedimentary fabrics of PDCs is imbricated and parallel to the flow direction (e.g., Ort, 1993;Cañón-Tapia and Mendoza-Borunda, 2014;Alva-Valdivia et al, 2017). In contrast, the development of shear and post-emplacement fabrics (e.g., slumping, compaction) seems absent in our samples, because the sampled RBI units are predominantly nonwelded (Mazzoni and Licitra, 2000;Melnick et al, 2006) and present emplacement temperature below the minimum welding temperature (Haag et al, 2020).…”

Section: Flow Dynamics and Emission Areamentioning

confidence: 62%

“…In the past decades the AMS has been extensively applied to pyroclastic deposits, mainly as a tool for source area identification (e.g., Palmer and MacDonald, 1999;Hong et al, 2006;Alva-Valdivia et al, 2017). Despite that, few studies have examined how AMS relates to flow dynamics (e.g., Fisher et al, 1993;Baer et al 1997;Ort et al, 2003Ort et al, , 2014Giordano et al, 2008;LaBerge et al, 2009).…”

Section: Implications For Pdc Dynamicsmentioning

confidence: 99%

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AMS and rock magnetism in the Caviahue-Copahue Volcanic Complex (Southern Andes): emission center, flow dynamics, and implications to the emplacement of non-welded PDCs

Haag¹,

Sommer²,

Savian³

et al. 2022

Preprint

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Pyroclastic deposits can cover significant areas and register major geological events. Despite their importance, understanding depositional dynamics of pyroclastic density currents (PDCs) and linking explosive deposits to their emission centers is still a challenge, especially in the case of non-welded, massive ignimbrites. Located in the Southern Andes, the Caviahue Copahue Volcanic Complex (CCVC) comprises one of the most active volcanic centers in the Andean Belt. This volcanic complex hosts massive ignimbrites with both source emplacement poorly constrained, currently grouped in the Riscos Bayos Ignimbrites (RBI). In this contribution, we perform a full magnetic characterization and anisotropy of magnetic susceptibility (AMS) study on the massive RBI of the CCVC. The magnetic characterization was performed using magnetic experiments including isothermal remanet magnetization, thermomagnetic curves, hysteresis loops, first-order reversal curves, and scanning electron microscopy. Magnetic experiments indicate primary, multi-domain, high Curie temperature titanomagnetites as the AMS carriers. Ellipsoids are predominately oblate, with a low degree of anisotropy and east-southeastward imbrication. This fabric arrangement is consistent with PDC sedimentary fabrics deposited under laminar flow conditions. Despite RBI massive structure AMS data reveals changes in transport capacity of the PDC and particle organization. These changes are marked by increasing AMS dispersion and decreasing degree of anisotropy up-section within flow units. Directional statistics of AMS data implies the Las Mellizas Caldera as the emission center of RBI. The reconstructed flow path also suggests the PDC overrun of the Caviahue Caldera topographic rim. This study highlights the application of AMS to the identification of emission centers of explosive deposits, featuring its application to massive ignimbrites.

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Section: Flow Dynamics and Emission Areamentioning

confidence: 62%

Section: Implications For Pdc Dynamicsmentioning

confidence: 99%

AMS and rock magnetism in the Caviahue-Copahue Volcanic Complex (Southern Andes): emission center, flow dynamics, and implications to the emplacement of non-welded PDCs

Haag¹,

Sommer²,

Savian³

et al. 2022

Preprint

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“…2). In the cooling branch, the absence of the second T C and lower susceptibility and the irreversibility below 500 °C are owed to the destruction of Ti-maghemite possibly into Ti-hematite at high temperatures (e.g., Alva-Valdivia et al 2017.…”

Section: Magnetic Mineralogymentioning

confidence: 99%

Curie temperature of weakly shocked target basalts at the Lonar impact crater, India

Agarwal

Alva‐Valdivia

2019

Earth Planets Space

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The study investigates Curie temperature (T C), bulk magnetic susceptibility, hysteresis, and X-ray diffraction pattern of in situ target basalts of Lonar impact crater, India. The main magnetic phase in the target basalt is low-Ti titanomagnetite. This study reveals an increase in T C and decrease in magnetic susceptibility and in full width at half maxima of the 311 peaks of titanomagnetite with distance from the crater center. Changes in crystal lattice of titanomagnetite, such as straining of 311 peaks, decrease in apparent crystallite size, and grain fragmentation may be among the possible reasons for the observed trends in T C and magnetic susceptibility. However, they both do not show any correlation between each other, indicating that different shock-induced processes affect them.

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“…The tectonics activity, considered active in the present days make possible local displacements and vertical axis rotations (e.g. Alva-Valdivia et al, 2017;Alva-Valdivia et al, 2019), with low influence in the general setting of all the TMVB. However, if this active tectonic was clearly the trigger of the volcanic activity in central México (Gomez-Tuena et al, 2007), no large movement that would have disturbed the TMVB directions could be detected, at least for the last 1.5 Ma.…”

Section: The Tmvb Paleomagnetic Dataset and The Time Averaged Dipole mentioning

confidence: 99%

Analysis of geomagnetic secular variation for the last 1.5 Ma recorded by volcanic rocks of the Trans Mexican Volcanic Belt: new data from Sierra de Chichinautzin, Mexico

Rodríguez-Trejo

Alva‐Valdivia

Perrin

et al. 2019

Geophysical Journal International

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Summary The great wealth of volcanism along the Trans Mexican Volcanic Belt (TMVB) and the need to improve the secular variation curve of the Earth magnetic field of the region is the aim of this research. 300 oriented cores from 33 sites and 21 individual cooling units were acquired from Sierra de Chichinautzin volcanic field (ChVF) and Sierra de Santa Catarina (SSC). Directional analysis and rock magnetic experiments were performed (e.g. thermal demagnetization, hysteresis loop, susceptibility vs temperature), achieving 21 new averaged palaeomagnetic directions. New results are consistent with the previous studies on the same cooling unit. We compiled all the palaeomagnetic studies performed on the ChVF, updating age and calculating an average direction per cooling unit and estimating an overall mean direction for the ChVF (Dec = 359.1°, Inc = 35.3°, N = 33, k = 21.6, α95 = 5.5°, Plat = 87.7° N, Plong = 227.4° E, K = 31.8, A95 = 4.5°). Afterwards, we compiled all the previous palaeomagnetic studies along the whole TMVB with age ranging from 0 to 1.5 Ma, and constrained the directional analyses by specific quality criteria such as well-defined age, number of samples and quality of kappa) on the cooling unit consistency. The mean direction and virtual geomagnetic pole (VGP) estimated for the TMVB, during the periods 0–40 ka and 0–1.5 Ma, are close to the geographic pole, supporting the validity of the geocentric axial dipole hypothesis. The directional results of this study also fit well with the predictions at Mexico City of the models SHA.DIF.14k and CALS10k2 calculated for the last 14 ka. The dispersion of the VGP's on the TMVB are also consistent with the expected values proposed by different models of palaeosecular variation. However, large gaps in the temporal record remain that should be filled by further palaeomagnetic studies.

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Paleomagnetic and AMS studies of the El Castillo ignimbrite, central-east Mexico: Source and rock magnetic nature

Cited by 19 publications

References 44 publications

AMS and rock magnetism in the Caviahue-Copahue Volcanic Complex (Southern Andes): emission center, flow dynamics, and implications to the emplacement of non-welded PDCs

AMS and rock magnetism in the Caviahue-Copahue Volcanic Complex (Southern Andes): emission center, flow dynamics, and implications to the emplacement of non-welded PDCs

Curie temperature of weakly shocked target basalts at the Lonar impact crater, India

Analysis of geomagnetic secular variation for the last 1.5 Ma recorded by volcanic rocks of the Trans Mexican Volcanic Belt: new data from Sierra de Chichinautzin, Mexico

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