Interpretation of anisotropy of magnetic susceptibility fabric of ignimbrites in terms of kinematic and sedimentological mechanisms: An Anatolian case-study

Pennec, Jean–Luc Le; Chen, Yan; Diot, Hervé; Froger, Jean‐Luc; Gourgaud, Alain

doi:10.1016/s0012-821x(97)00215-x

Cited by 61 publications

(40 citation statements)

References 44 publications

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“…Various studies (Khan 1962, Bolshakov & Skorodkin 1967, Le Pennée et al 1998, Zanella et al 1999 showed that the degree of magnetic anisotropy in volcanic rocks is usually low, less than 10%, while the bulk susceptibility ranges according to the magnetic mineralogy, but most commonly is of the order of 10" 3 -10" 2 SI. The low anisotropy suggests that the orientation mechanism of ferromagnetic minerals is not very effective.…”

Section: General Character Of Ams In Volcanicsmentioning

confidence: 99%

“…the flow plane and/or direc tion, of these rocks has been demonstrated in volcanic formations throughout the world (e.g. Dragoni et al 1997, Le Pennée et al 1998, Smith 1998, Varga et al 1998, Archanjo et al 2000, Canon-Tapia & Pinkerton 2000. The method favours great acceptance because: it exhibits high sensitivity, is non time-consuming and can be applied to a variety of formations -lava flows, pyroclastic deposits, ash and tuff flows, ignimbrites, sills and dykes.…”

Section: Introductionmentioning

confidence: 99%

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Anisotropy of Magnetic Susceptibility (Ams) in Volcanic Formations: Theory and Preliminary Results From Recent Volcanics of Broader Aegean.

Zananiri

Kondopoulou

2004

geosociety

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The anisotropy of magnetic susceptibility (AMS) is a physical property of rocks widely used in petrofabric studies and other applications. It is based on the measurement of low-field magnetic susceptibility in different directions along a sample. From this process several scalar properties arise, defining the magnitude and symmetry of the AMS ellipsoid, along with the magnetic foliation, namely the magnetic fabric. Imaging the sense of magma flow in dykes is an important task for volcanology; the magnetic fabric provides a fast and accurate way to infer this flow direction. Moreover, the AMS technique can be used in order to distinguish sills and dykes, a task that is almost impossible by using only field observations. Finally in the case of lava flows, the method can be applied to define the local flow conditions and to indicate the position of the "paleo" source region. However, this technique is quite new in Greece. Some preliminary results from volcanic formations of continental Greece and Southern Aegean are presented (Aegina, Almopia, Elatia, Gavra, Kos, Patmos, Samos, Samothraki and Santorini).

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Section: General Character Of Ams In Volcanicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Anisotropy of Magnetic Susceptibility (Ams) in Volcanic Formations: Theory and Preliminary Results From Recent Volcanics of Broader Aegean.

Zananiri

Kondopoulou

2004

geosociety

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“…The K 1 axis is usually interpreted to be parallel to the flow direction and thus plunges towards the source (Knight et al, 1986). The use of the K 1 axis alone as a proxy for flow direction is not always reliable (Seaman et al, 1991;Hillhouse and Wells, 1991;Ort, 1993;Le Pennec et al, 1998) and a different methodology must be used to interpret the magnetic data. The imbrication angle of the magnetic foliation plane, which equivalents the deviation of the K 3 axes from the normal to the macroscopic flow plane, offers another method to distinguish the flow direction of ignimbrite (Henry, 1980;Thompson and Oldfield, 1986) (Fig.…”

Section: Sampling Methods and Ams Measurementsmentioning

confidence: 99%

Hazards from Pyroclastic Density Currents at Mount Bamenda (West-Cameroon, Cameroon Volcanic Line): Mapping and Assessment by AMS Method

Dedzo¹,

Kamgang²,

Njonfang³

et al. 2015

American Journal of Geoscience

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Hazards related to pyroclastic density current continue to raise victims on many volcanoes in our planet. The Cameroon is not spared to this type of hazard because deposits of pyroclastic flows and surges are found on Mount Bamenda; products of this volcano are relatively young (27-0 Ma). Besides Mount Bamenda, Mounts Bambouto and Oku are the only volcanoes located in the central part of the Cameroon Volcanic Line where these ignimbritic deposits are found. Several factors highlight dangerousness and damage that can cause ignimbritic flows on the flanks of this volcano. This is essentially the high aspect ratio of these ignimbrites, the important population (about 750,000 people) that lives on the slopes and around the volcano. In order to have an idea of a nowadays ignimbritic eruption scenario on Bamenda volcano, the Anisotropy of Magnetic Susceptibility (ASM) method is used in this study to highlight the palaeoflow in ancient deposits of ignimbrites which are mostly discontinuous and isotropic. Results of AMS study are used to produce map of hazards and assess risks that may be related with such eruptions in Bamenda volcano.

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“…The maximum axis (K 1 ) is typically interpreted to be parallel to the flow direction and thus plunges towards the source [11]. The use of the K 1 susceptibility axis alone as a proxy for flow direction is not always reliable [11,13,[20][21][22], and a different approach must be used to interpret the AMS data. The imbrication angle of the magnetic foliation plane, which equals the deviation of the K 3 axes from the normal to the macroscopic flow plane, provides an alternative method to discern the flow direction of ignimbrite deposits [23,24].…”

Section: Sampling Methods and Ams Measurementsmentioning

confidence: 99%

Mapping and Assessment of Volcanic Hazards Related to the Ignimbritic Eruption by AMS in Bambouto Volcano (Cameroon Volcanic Line)

Dedzo

Kamgang²,

Njonfang³

et al. 2013

TOGEOJ

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Pyroclastic deposits constitute major components of explosive volcanic activity. To help improve the safety of the population faced with natural disasters, a study is carried out at Bambouto volcano with a view to map potential hazards related to pyroclastic flows. The Bambouto volcano is indeed considered to be still active since the recent discovery of Quaternary basalts (0.5 Ma) at Totap, a locality situated near the Bambouto Caldera. This discovery has led to reclassify Mount Bambouto among active volcanoes of Cameroon and, therefore, considered as potentially dangerous. The dangerousness of this volcano is accentuated by the presence of ignimbrites that are witnesses of ancient pyroclastic flows. Because a map of volcanic hazards is non-existent on the volcano, anisotropy of magnetic susceptibility (AMS) is the method used in this paper to characterize magnetic fabrics and provides an estimate of flow direction of each ignimbrite sheet (represented by massive lapilli tuff and massive lithic breccia facies). Inferred transport directions based on the AMS data and field indicators show that Bambouto Caldera is the source of main pyroclastic deposits of Mount Bambouto. These results have enabled us to produce a new hazard map related to potential future pyroclastic flows.

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Interpretation of anisotropy of magnetic susceptibility fabric of ignimbrites in terms of kinematic and sedimentological mechanisms: An Anatolian case-study

Cited by 61 publications

References 44 publications

Anisotropy of Magnetic Susceptibility (Ams) in Volcanic Formations: Theory and Preliminary Results From Recent Volcanics of Broader Aegean.

Anisotropy of Magnetic Susceptibility (Ams) in Volcanic Formations: Theory and Preliminary Results From Recent Volcanics of Broader Aegean.

Hazards from Pyroclastic Density Currents at Mount Bamenda (West-Cameroon, Cameroon Volcanic Line): Mapping and Assessment by AMS Method

Mapping and Assessment of Volcanic Hazards Related to the Ignimbritic Eruption by AMS in Bambouto Volcano (Cameroon Volcanic Line)

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