Distribution of monogenetic volcanism along the Cameroon Line

Mapping Intimacies ◽

10.5194/egusphere-egu21-1755 ◽

2021 ◽

Author(s):

Christoph Schmidt ◽

Christian Laag ◽

Jörn Profe

Keyword(s):

Spatial Organization ◽

Volcanic Eruptions ◽

Volcanic Field ◽

Monogenetic Volcanism ◽

Area Of Interest ◽

Short Period ◽

Volcanic Fields ◽

Monogenetic Volcanoes ◽

Spatio Temporal ◽

Scoria Cones

Volcanic eruptions may constitute a severe threat for local communities and their infrastructure. Important information as to the prediction of future eruption sites and the likelihood of activity can be obtained by analysis of spatio-temporal eruption pattern in an area of interest. The fact that monogenetic volcanoes, unlike polygenetic ones, erupt only once (within a geologically short period) at a certain spot and then volcanic activity jumps to another spot, renders a quantitative, probabilistic assessment of eruptive cycles challenging. In other words, the purely temporal risk assessment relevant for polygenetic volcanism has to be supplemented by a spatial dimension in case of monogenetic volcanic fields to allow for a combined spatio-temporal forecast.While the eruption history of many stratovolcanoes along the Cameroon Line (CL) in Central Africa is comparatively well studied, only fragmentary data exists on the distribution and timing of monogenetic volcanism (mainly scoria cones and maars), presumably associated with Quaternary timescales. Here, we undertake an initial step in closing this gap and present for the first time a map of monogenetic volcanic features for most parts of the CL. Scoria cones and maars were identified by their characteristic morphologies using a combination of field knowledge, digital elevation models and satellite imagery. More than ~1300 scoria cones and 41 maars were detected and divided into eight monogenetic volcanic fields (MVF), as defined by the convex hull of the outermost vents: Bioko, Mt. Cameroon, Kumba, Tombel Graben (including Mt. Manengouba), Noun, Oku, Adamawa, and Biu (Nigeria). However, due to the rugged topography in the Oku volcanic field and the difficulty of identifying volcanic features remotely, the number of mapped scoria cones appears rather incomplete.While the delineation of individual MVF bears an inherent subjective moment, statistical analyses of the primary dataset clearly shows that the mean nearest neighbour distance increases from <1 km to ~2 km from the oceanic sector (Bioko, Mt. Cameroon) in the southwest towards the continental part in the northeast (Adamawa, Biu). Correspondingly, the areal density of monogenetic features decreases along this gradient by about one order of magnitude from >0.2 km-2 (southwest) to 0.02 km-2 (northeast). This finding is in general agreement with prior geochronological results, indicating increased Quaternary activity towards the central and oceanic part of the CL (e.g., Njome and de Wit, 2014). Tests for the spatial organization of monogenetic volcanoes using the Geological Image Analysis Software (GIAS, v2; Beggan and Hamilton, 2010) revealed that the vents in all MVF are clustered (98% credible interval), thus allowing inferences to be drawn on the tectonic control of (future) eruption locations.&#160;ReferencesBeggan, C., Hamilton, C.W., 2010. New image processing software for analyzing object size-frequency distributions, geometry, orientation, and spatial distribution. Computers & Geosciences 36, 539-549.Njome, M.S., de Wit, M.J., 2014. The Cameroon Line: Analysis of an intraplate magmatic province transecting both oceanic and continental lithospheres: Constraints, controversies and models. Earth-Science Reviews 139, 168-194.

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Comprehensive palaeomagnetic study of San Borja and Jaraguay monogenetic volcanic fields, Baja California (28–30° N): considerations on latitudinal corrections

Geophysical Journal International ◽

10.1093/gji/ggab064 ◽

2021 ◽

Author(s):

A N Mahgoub ◽

B I García-Amador ◽

L M Alva-Valdivia

Keyword(s):

Dipole Moment ◽

Late Miocene ◽

Baja California ◽

Temporal Distribution ◽

Magnetic Minerals ◽

Kinematic Evolution ◽

Oxidation Reduction ◽

Volcanic Fields ◽

Spatio Temporal ◽

Northwestern Mexico

Summary We report 24 palaeomagnetic directions and 10 high-quality Thellier-derived palaeointensity (PI) values, obtained from 27 sites located in Baja California Peninsula, northwestern Mexico. Sampling was done in four rock units (magnesian andesites, calc-alkaline lavas, ignimbrites, adakites) belonging to San Borja and Jaraguay monogenetic volcanic fields. These units have erupted between ∼ 15 and 2.6 Ma (previous K-Ar and 40Ar/39Ar data); hence results are presented in two consecutive periods: middle-late Miocene and Pliocene. The identified main magnetic minerals in the sampled sites are titanomagnetite, magnetite, and minor hematite, of variable grain size, present as intergrowths or surrounding grains, which reflect varying oxidation/reduction conditions during emplacement of high-temperature magmas. Based on previous geological and geophysical records, the kinematic evolution was carefully considered in the region, allowing for the independent restoration of the palaeoposition of each sampled site. Previous palaeodirections were also evaluated and corrected for tectonic motion in order to combine them with present data. Accordingly, a number of 15 and 36 directional data are used to calculate palaeopole position for Pliocene and middle-late Miocene periods, respectively, selected from a total of 74 data points. Pliocene (Plat = 87.8°, Plong = 147.5°, K = 41.06, A95 = 6.0°) and middle-late Miocene (Plat = 86.0°, Plong = 172.7°, K = 41.08, A95 = 3.8) palaeopole positions, calculated after tectonic corrections, are not statistically different from expected North American reference pole. Tectonic correction for Middle-late Miocene virtual geomagnetic poles plays an important role in reducing the resultant tilting from 2.7° to -0.8°. PI mean were calculated for Pliocene and middle-late Miocene periods at 29.2 ± 9.1 μT and 23.2 ± 6.3 μT, respectively. Compiling global filtered PI data, together with our results, indicates that the strength of the geomagnetic field during middle-late Miocene was weak (virtual dipole moment = 5.0 ± 2.2 × 1022 Am2) compared to Pliocene (6.4 ± 2.8 × 1022 Am2), and also relative to the present-day value (7.6 × 1022 Am2). This indicates the global nature of the low dipole moment during the middle-late Miocene period. However, issues related to the spatio-temporal distribution of PI data still present an obstacle to validating these suggestions; therefore, more reliable data are still needed.

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Effusive Monogenetic Volcanism

10.5772/intechopen.94387 ◽

2020 ◽

Author(s):

Hugo Murcia ◽

Károly Németh

Keyword(s):

Classification Scheme ◽

Wide Spectrum ◽

Lava Flows ◽

Magma Ascent ◽

Explosive Activity ◽

Monogenetic Volcanism ◽

Future Studies ◽

Lava Domes ◽

Tectonic Settings ◽

Monogenetic Volcanoes

The study of monogenetic volcanism around Earth is rapidly growing due to the increasing recognition of monogenetic volcanic edifices in different tectonic settings. Far from the idea that this type of volcanism is both typically mafic and characteristic from intraplate environments, it occurs in a wide spectrum of composition and geological settings. This volcanism is widely known by the distinctive pyroclastic cones that represent both magmatic and phreatomagmatic explosive activity; they are known as scoria or spatter cones, tuff cones, tuff rings, maars and maar-diatremes. These cones are commonly associated with lava domes and usually accompanied by lava flows as part of their effusive eruptive phases. In spite of this, isolated effusive monogenetic emissions also appear around Earth’s surface. However, these isolated emissions are not habitually considered within the classification scheme of monogenetic volcanoes. Along with this, many of these effusive volcanoes also contrast with the belief that this volcanism is indicative of rapidly magma ascent from the asthenosphere, as many of the products are strongly evolved reflecting differentiation linked to stagnation during ascent. This has led to the understanding that the asthenosphere is not always the place that directly gives rise to the magma batches and rather, they detach from a crustal melt storage. This chapter introduces four singular effusive monogenetic volcanoes as part of the volcanic geoforms, highlights the fact that monogenetic volcanic fields can also be associated with crustal reservoirs, and outlines the processes that should occur to differentiate the magma before it is released as intermediate and acidic in composition. This chapter also provides an overview of this particular volcanism worldwide and contributes to the monogenetic comprehension for future studies.

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Eruptive frequency of the Bora-Baricha-Tullu Moye (BBTM) volcanic system in the Central Main Ethiopian Rift

10.5194/egusphere-egu21-13966 ◽

2021 ◽

Author(s):

Amdemichael Zafu Tadesse ◽

Karen Fontijn ◽

Abate Assen Melaku ◽

Ermias Filfilu Gebru ◽

Victoria Smith ◽

...

Keyword(s):

Late Quaternary ◽

Volcanic Eruptions ◽

Volcanic Field ◽

Tectonic Activity ◽

Explosive Eruptions ◽

Ethiopian Rift ◽

Rift System ◽

Diagnostic Features ◽

Volcanic System ◽

Main Ethiopian Rift

The Main Ethiopian Rift (MER) is the northern portion of the East African Rift System and separates the Eastern and Western plateaus of Ethiopia. The recent volcanic and tectonic activity is largely focused within the rift basin along a 20 km wide zone on the rift floor. Large silicic volcanic complexes are aligned along this central rift axis but their eruptive histories are not well constrained.The Bora-Baricha-Tullu Moye (BBTM) volcanic field is situated in the central Main Ethiopian Rift and has a different appearance than the other MER volcanic systems. The BBTM constitutes several late Quaternary edifices, the major ones are: Tullu Moye, Bora and Baricha. In addition, there are multiple smaller eruptive vents (e.g. Oda and Dima), cones, and domes across the ca. 20 X 20 km wide area. Currently, there is very little information on the frequency and magnitude of past volcanic eruptions. We present a new dataset of field observations, componentry, petrography, geochronology (40Ar/39Ar), and glass major and trace element chemistry. The data are assessed as potential fingerprints to assign diagnostic features and correlate units across the area, and establish a tephrostratigraphic framework for the BBTM volcanic field.Two large-volume and presumably caldera-forming eruptions are identified, the younger of which took place at 100 ka. The volcanic products exposed in the BBTM area show that the volcanic field has undergone at least 20 explosive eruptions since then. The post-caldera eruptions have comenditic (Tullu Moye) and pantelleretic (Bora and Baricha) magma compositions. Other smaller edifices such as Oda and Dima also erupted pantelleritic magmas, and only differ slightly in composition than tephra of Bora and Baricha. Tullu Moye had two distinct explosive eruptions that dispersed tephra up to 14 km away and on to the eastern plateau. Bora and Baricha together had at least 8 explosive eruptions. Their deposits can be distinguished by their light grey color and unique lithic components. Oda had 7 eruptions, the most recent of which generated a pyroclastic density current that travelled up to 10 km away from the vent. Dima experienced at least 3 eruptions, generating tephra with a bluish-grey colour.This mapping and compositional analysis of the deposits from the BBTM in the MER indicates that the region has been more active in the last 100 ka than previously thought, which has implications for hazards assessments for the region.

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Spatio-Temporal Data Mining for Air Pollution Problems

Encyclopedia of Data Warehousing and Mining, Second Edition ◽

10.4018/978-1-60566-010-3.ch277 ◽

2011 ◽

pp. 1815-1822 ◽

Cited By ~ 1

Author(s):

Seoung Bum Kim ◽

Chivalai Temiyasathit ◽

Sun-Kyoung Park ◽

Victoria C.P. Chen

Keyword(s):

Data Mining ◽

Air Pollution ◽

Real Data ◽

Ambient Air ◽

Ambient Air Pollution ◽

Temporal Data Mining ◽

Area Of Interest ◽

Mining Methods ◽

Spatio Temporal ◽

Temporal And Spatial Characteristics

Vast amounts of data are being generated to extract implicit patterns of ambient air pollution. Because air pollution data are generally collected in a wide area of interest over a relatively long period, such analyses should take into account both temporal and spatial characteristics. Furthermore, combinations of observations from multiple monitoring stations, each with a large number of serially correlated values, lead to a situation that poses a great challenge to analytical and computational capabilities. Data mining methods are efficient for analyzing such large and complicated data. Despite the great potential of applying data mining methods to such complicated air pollution data, the appropriate methods remain premature and insufficient. The major aim of this chapter is to present some data mining methods, along with the real data, as a tool for analyzing the complex behavior of ambient air pollutants.

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Aging of basalt volcanic systems and decreasing CO2 consumption by weathering

Earth Surface Dynamics ◽

10.5194/esurf-7-191-2019 ◽

2019 ◽

Vol 7 (1) ◽

pp. 191-197 ◽

Cited By ~ 4

Author(s):

Janine Börker ◽

Jens Hartmann ◽

Gibran Romero-Mujalli ◽

Gaojun Li

Keyword(s):

Age Distribution ◽

Aging Effect ◽

Hydrothermal Activity ◽

Volcanic Field ◽

Critical Zone ◽

Volcanic System ◽

Reactive Material ◽

Volcanic Fields ◽

Basalt Weathering ◽

Aging Function

Abstract. Basalt weathering is one of many relevant processes balancing the global carbon cycle via land–ocean alkalinity fluxes. The CO2 consumption by weathering can be calculated using alkalinity and is often scaled with runoff and/or temperature. Here, it is tested if the surface age distribution of a volcanic system derived by geological maps is a useful proxy for changes in alkalinity production with time. A linear relationship between temperature normalized alkalinity fluxes and the Holocene area fraction of a volcanic field was identified using information from 33 basalt volcanic fields, with an r2=0.93. This relationship is interpreted as an aging function and suggests that fluxes from Holocene areas are ∼10 times higher than those from old inactive volcanic fields. However, the cause for the decrease with time is probably a combination of effects, including a decrease in alkalinity production from material in the shallow critical zone as well as a decline in hydrothermal activity and magmatic CO2 contribution. The addition of fresh reactive material on top of the critical zone has an effect in young active volcanic settings which should be accounted for, too. A comparison with global models suggests that global alkalinity fluxes considering Holocene basalt areas are ∼60 % higher than the average from these models imply. The contribution of Holocene areas to the global basalt alkalinity fluxes is today however only ∼5 %, because identified, mapped Holocene basalt areas cover only ∼1 % of the existing basalt areas. The large trap basalt proportion on the global basalt areas today reduces the relevance of the aging effect. However, the aging effect might be a relevant process during periods of globally intensive volcanic activity, which remains to be tested.

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The Christiana–Santorini–Kolumbo Volcanic Field

Elements ◽

10.2138/gselements.15.3.171 ◽

2019 ◽

Vol 15 (3) ◽

pp. 171-176 ◽

Cited By ~ 2

Author(s):

Paraskevi Nomikou ◽

Christian Hübscher ◽

Steven Carey

Keyword(s):

Eastern Mediterranean ◽

Eastern Mediterranean Region ◽

Aegean Sea ◽

Volcanic Eruptions ◽

Volcanic Field ◽

Explosive Eruptions ◽

Human Populations ◽

Mass Wasting ◽

Geological Processes ◽

Research Activities

The Christiana–Santorini–Kolumbo volcanic field in the South Aegean Sea (Greece) is one of the most important in Europe, having produced more than 100 explosive eruptions in the last 400,000 years. Its volcanic centers include the extinct Christiana Volcano and associated seamounts, Santorini caldera with its intracaldera Kameni Volcano, Kolumbo Volcano, and 24 other submarine cones of the Kolumbo chain. Earthquakes, volcanic eruptions, submarine mass wasting, neotectonics and gas releases from these centers pose significant geohazards to human populations and infrastructures of the Eastern Mediterranean region. Defining the geological processes and structures that contribute to these geohazards will provide an important framework to guide future monitoring and research activities aimed at hazard mitigation.

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Interaction between intra-continental sedimentary basins and small-volume monogenetic volcanism: Argamasilla and Calzada-Moral basins, Campo de Calatrava Volcanic Field, Spain

Journal of Iberian Geology ◽

10.5209/rev_jige.2012.v38.n2.40466 ◽

2013 ◽

Vol 38 (2) ◽

Cited By ~ 2

Author(s):

A. Herrero-Hernández ◽

F.J. López-Moro ◽

F. Gómez-Fernández ◽

A. Martín-Serrano

Keyword(s):

Small Volume ◽

Sedimentary Basins ◽

Volcanic Field ◽

Monogenetic Volcanism

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The control of preexisting faults on the distribution, morphology, and volume of monogenetic volcanism in the Michoacán-Guanajuato Volcanic Field

Geological Society of America Bulletin ◽

10.1130/b35397.1 ◽

2020 ◽

Vol 132 (11-12) ◽

pp. 2455-2474 ◽

Cited By ~ 4

Author(s):

Martha Gabriela Gómez-Vasconcelos ◽

José Luis Macías ◽

Denis Ramón Avellán ◽

Giovanni Sosa-Ceballos ◽

Víctor Hugo Garduño-Monroy ◽

...

Keyword(s):

Hanging Wall ◽

Temporal Distribution ◽

Volcanic Field ◽

Fault System ◽

Volcanic Stratigraphy ◽

Listric Fault ◽

Tectonic Processes ◽

State Of Stress ◽

Geological Map ◽

Scoria Cones

Abstract Interactions between volcanic and tectonic processes affect the distribution, morphology, and volume of eruptive products in space and time. The Queréndaro area in the eastern Michoacán-Guanajuato Volcanic Field affords an exceptional opportunity to understand these relationships. Here, a Pleistocene lava plateau and 20 monogenetic volcanoes are vented from an active ENE-striking segment of the Morelia-Acambay fault system. Thirteen scoria cones are aligned along this structure, vented from an extensional gap in between two rotated hanging wall blocks of a listric fault. A new geological map, volcanic stratigraphy, and 40Ar/39Ar dating indicate that this lava plateau and volcanic cluster were emplaced from 0.81 to 0.25 Ma by 11 intermittent eruptive epochs separated by ca. 0.05 Ma, emplacing a total magma volume of 5 km3. Petrography and chemistry of rocks suggest that all volcanic structures were fed by three different magma batches but vented from independent feeder dikes. Our results indicate that preexisting faults exert a strong influence on volcanic spatial and temporal distribution, volcanic morphology, magma volume, and eruptive dynamics in this area. ENE-breached and ENE-elongated scoria cones indicate parallel subsurface fissure and feeder dikes. Additionally, points of maximum fault dilation at depth related to a transtensive state of stress coincide with less fragmented deposits and larger magma volumes. Furthermore, this study raises important questions on the geodynamics of volcano-tectonic interactions possible in similar monogenetic volcanic alignments worldwide.

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