The relationship between eruptive activity, flank collapse, and sea level at volcanic islands: A long‐term (>1 Ma) record offshore Montserrat, Lesser Antilles
Maya CoussensDeborah Wall-PalmerPeter J. TallingSebastian WattMichael CassidyMartin JutzelerMichael ClareJames E. HuntMichael MangaThomas M. GernonMartin R. PalmerStuart J. HatterGeorges BoudonDaisuke EndoAkihiko FujinawaRobert G. HatfieldMatthew J. HornbachOsamu IshizukaKyoko S. KataokaAnne Le FriantFukashi MaenoM. C. McCantaA. Stinton
38
Citation
110
Reference
10
Related Paper
Citation Trend
Abstract:
Abstract Hole U1395B, drilled southeast of Montserrat during Integrated Ocean Drilling Program Expedition 340, provides a long (>1 Ma) and detailed record of eruptive and mass‐wasting events (>130 discrete events). This record can be used to explore the temporal evolution in volcanic activity and landslides at an arc volcano. Analysis of tephra fall and volcaniclastic turbidite deposits in the drill cores reveals three heightened periods of volcanic activity on the island of Montserrat (∼930 to ∼900 ka, ∼810 to ∼760 ka, and ∼190 to ∼120 ka) that coincide with periods of increased volcano instability and mass‐wasting. The youngest of these periods marks the peak in activity at the Soufrière Hills volcano. The largest flank collapse of this volcano (∼130 ka) occurred toward the end of this period, and two younger landslides also occurred during a period of relatively elevated volcanism. These three landslides represent the only large (>0.3 km 3 ) flank collapses of the Soufrière Hills edifice, and their timing also coincides with periods of rapid sea level rise (>5 m/ka). Available age data from other island arc volcanoes suggest a general correlation between the timing of large landslides and periods of rapid sea level rise, but this is not observed for volcanoes in intraplate ocean settings. We thus infer that rapid sea level rise may modulate the timing of collapse at island arc volcanoes, but not in larger ocean‐island settings.Keywords:
Mass wasting
Submarine landslide
The early Pleistocene Tugm Tephra Bed in the Niigata region and the Kd18 Tephra Bed in the Boso Peninsula were correlated to the Ashino Pyroclastic Flow Deposit in the Aizu region. They contain bubble-junction type glass shards and high quartz in common. Chemical composition of glass shard and orthopyroxene (Mg#=63.6-66.0) of these tephra is also coincident. These tephras are expected to be found as marker beds in Japan.
Peninsula
Cite
Citations (7)
Cite
Citations (0)
The Oligocene Colestin Formation consists of volcaniclastic apron sequence that records the initiation of Cascade volcanism in the western Cascade Range of southern Oregon. The formation in the type area is largely confined to an east-west-trending graben approximately 8 km wide. This graben and other smaller grabens within it developed to the west of and perpendicular to the axis of the Oligocene Cascade arc. The apron, which fills and locally overflows the graben, consists of coalesced lobes of volcaniclastic and pyroclastic deposits and lesser amounts of lava flows. Abrupt lateral facies changes on a scale of tens to hundreds of meters were produced by the lobe style of deposition and contemporaneous basin faulting. Interstratified with the discontinuous apron sediments are marker units that consist of pyroclastic flows, paleosols, and lava-flow sequences. In the upper half of the formation, the apron can be subdivided into informal members (lobes and sequences of lobes), which can be mapped according to their composition and stratigraphic position. Each member formed during a distinct interval of volcanism. An epiclastic lobe in the upper part of the formation, containing debris-flow and hyperconcentrated flood-flow deposits, represents a period of effusive or mildly explosive andesitic and basaltic volcanism. Thismore » epiclastic lobe pinches out to the south under a member that consists of tuffaceous sandstones and interbedded welded and nonwelded pyroclastic flows. The pulselike style of apron growth was produced by the episodic shifting of volcanism along the arc.« less
Cite
Citations (0)
We subdivided volcaniclastic layers drilled during Leg 157 around Gran Canaria at distances up to 70 km from the shore of the island at Hole 953C, 955A, and 956B deposited between 14 and ~11.5 Ma into >100 volcaniclastic units at each site.Most volcaniclastic layers are <20 cm thick, but complex turbidite units up to 1.5 m thick make up 10% to 20% of all volcaniclastic units in Holes 953C and 956B.We distinguish several types of clasts: felsic vitroclasts, (1) bubble-wall/junction shards, (2) brown nonvesicular felsic shards, (3) welded tuff clasts, (4) pumice shards, and (5) sideromelane shards.Mineral phases comprise anorthoclase and lesser amounts of plagioclase, calcic and sodic amphibole (kaersutite, richterite, and edenite), clinopyroxene (titanaugite to aegirine), hypersthene, minor enstatite, phlogopite, Fe/Ti oxides, sphene, chevkinite, apatite, and zircon.Xenocrysts are dominantly titanaugite derived from the subaerial and submarine shield basalts.Lithoclasts are mainly tachylitic and crystalline basalt, the latter most common in Hole 953C, and fragments of felsic lava and ignimbrite.Bioclasts consist of open planktonic foraminifers and nannofossil ooze in the highly vitric layers, while filled planktonic foraminifers, benthic foraminifers, and a variety of shallow water calcareous and siliceous fossils and littoral skeletal debris are common in the basal coarser grained parts of turbidites.Volcaniclastic sedimentation during the time interval 14-9 Ma was governed dominantly by direct and indirect volcanic processes rather than by climate and erosion.Most volcaniclastic units thought to represent ignimbrite eruptions consist of a coarse basal part in which pumice and large brown nonvesicular and welded tuff shards and crystals dominate, and an upper part that commonly consists of thin turbidites highly enriched in bubble-wall shards.The prominent coarser grained and vitroclast-rich volcaniclastic layers were probably emplaced dominantly by turbidity currents immediately following entry of ash flows into the sea.The brown, blocky and splintery, dense, completely welded, dominantly angular to subrounded, partially to completely welded tuff shards are thought to have formed by quench fragmentation (thermal shock) as the hot pyroclastic flows entered the sea, fragmentation of cooling ignimbrite sheets forming cliffs along the shore, and water vapor explosions in shallow water.Well-sorted beds dominated by bubble-wall/junction shards may have formed by significant sorting processes during turbidite transport into the deep (300-4000 m) marine basins north and south of Gran Canaria.Some may also have been generated largely by grinding of pumice rafts and fallout and/or by interface-shearing of coignimbrite ash clouds traveling over the water surface.Generally fresh sideromelane shards that occur dispersed in many felsic volcaniclastic layers and in one hyaloclastite layer are mostly nonvesicular and blocky.They indicate submarine basaltic eruptions at water depths of several hundred meters on the slope of Gran Canaria synchronously with felsic ash flow eruptions on land.Most sideromelane shards are slightly evolved (4-6 wt% MgO), but shards in some layers are mafic (6-8 wt% MgO).Most shards have alkali basaltic compositions.The dense, iron-rich, moderately evolved basaltic magmas are thought to be the direct parent magmas for the trachytic to rhyolitic magmas of the Mogán Group.They were probably unable to erupt beneath the thick, low-density lid of the felsic magma reservoir below the large caldera but were erupted through lateral dikes onto the flanks of the submarine cone.Tholeiitic shards occur low in the stratigraphic section where peraluminous K-poor magmas were erupted, a correlation that supports the parental relationship.Heterogeneity in glass and crystal populations in the absence of other evidence for an epiclastic origin, probably largely reflect systematic primary compositional heterogeneity of most of the ignimbrites, which become more mafic toward the top.This gross compositional zonation is destroyed at the land/sea interface, where the ignimbrites are likely to have resulted in a chaotic buildup of large, quickly cooled, and fragmented mounds of hot ignimbrite.Post-emplacement, erosional mixing is probably reflected in volcaniclastic layers that are well bedded, contain a large amount of shallow water skeletal debris and rounded basaltic lithoclast, and show a wide spectrum of glass and mineral compositions.Basaltic lithoclasts are much more common in volcaniclastic layers at Hole 953C, probably because the northeastern shield basalts were highly dissected in this older part of the composite shield volcano prior to the beginning of ignimbrite volcanism at 14 Ma.As a result, many ignimbrites may have been channeled into the sea via deep canyons.In contrast, erosion was minimal during Mogán time in the southern half of the island, which was gently sloping and practically undissected, leading to concentric sedimentation on the volcanic apron.In general, the submarine, syn-ignimbrite turbidites have preserved a number of characteristics from the pristine stage of ash flow emplacement-especially shape and vesicularity of primary particles and the transient glassy state-that are lacking in the subaerial ignimbrites that cooled and devitrified at high temperatures.,
Cite
Citations (8)
Mass wasting
Submarine landslide
Submarine canyon
Continental Margin
Seafloor Spreading
Slope failure
Margin (machine learning)
Bathymetric chart
Passive margin
Steep slope
Cite
Citations (19)
Pyroclastic fall
Peléan eruption
Dense-rock equivalent
Cite
Citations (16)
Pyroclastic fall
Peléan eruption
Fragmentation
Vulcanian eruption
Cite
Citations (33)
Geosphere, August 2010, v. 6, p. 397-429, doi:10.1130/GES00515.1, Supplemental Tables - Excel file of four supplemental tables. File size is 1.5 MB.
Cite
Citations (0)
Foot (prosody)
Cite
Citations (0)