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

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Nøhr-Hansen, H., & Piasecki, S. (2002). Paleocene sub-basaltic sediments on Savoia Halvø, East Greenland. Geology of Greenland Survey Bulletin, 191, 111-116. https://doi.org/10.34194/ggub.v191.5137 _______________ Field work by the Geological Survey of Denmark and Greenland (GEUS) on Savoia Halvø, central East Greenland in 2001 (see also Larsen et al. 2002, this volume) included a study of sediments underlying the Palaeogene basalts on the south coast of Scoresby Sund (Fig. 1). The importance of this small exposure is based on the fact that it provides one of the few opportunities for establishing a marine biostratigraphic date for the sediments below the basalts. Dinoflagellate cysts from the sediments provide a maximum Early Paleocene age for the onset of the volcanism in central East Greenland. Reports from previous field work have mentioned the sediments (Hassan 1953; Birkenmajer 1972), but no precise age assignment was presented due to the absence of diagnostic fossils. The sub-volcanic sediments of Savoia Halvø represent the youngest preserved marine sedimentary deposits of the Upper Palaeozoic – Cenozoic rift-basins onshore East Greenland. The overlying Palaeogene flood basalts occasionally contain very thin sedimentary beds between the lava flows, but these were deposited above sea level. Neogene uplift of the East Greenland margin brought a definitive end to accumulation in the old sedimentary basins (Watt et al. 1986; Christiansen et al. 1992).

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Stratigraphy and age of the Eocene Igtertivâ Formation basalts, alkaline pebbles and sediments of the Kap Dalton Group in the graben at Kap Dalton, East Greenland

Bulletin of the Geological Society of Denmark ◽

10.37570/bgsd-2013-61-01 ◽

2013 ◽

Vol 61 ◽

pp. 1-18 ◽

Cited By ~ 1

Author(s):

Lotte Melchior Larsen ◽

Erik Vest Sørensen ◽

W. Stuart Watt ◽

Asger Ken Pedersen ◽

Robert A. Duncan

Keyword(s):

Field Work ◽

Lava Flows ◽

Radiometric Dating ◽

Dyke Swarm ◽

Geological Time ◽

Geological Time Scale ◽

The North ◽

Northward Propagation ◽

Volcanic Succession ◽

Good Agreement

A NE–SW-trending graben at Kap Dalton on the Blosseville Kyst contains an at least 600 m thick succession of Eocene basalt lavas and sediments. The succession has been investigated by new field work, geochemical analysis and radiometric dating by the 40Ar-39Ar incremental heating method. The results show that the volcanic succession comprises about 220 m of the uppermost plateau basalt formation, the Skrænterne Formation. This is separated from the overlying lava flows of the Igtertivâ Formation by 7 m of sediments that represent a period of around six million years. The two formations can be distinguished by different trace element ratios. The Igtertivâ Formation comprises an at least 300 m thick main succession of flows dated to 49.09 ± 0.48 Ma, overlain by sediments of the Bopladsdalen Formation. A basal conglomerate in the sediments contains pebbles of alkaline igneous rocks of which three were dated at 49.17 ± 0.35 Ma, 47.60 ± 0.25 Ma, and 46.98 ± 0.24 Ma. The sediments are thus younger than 47 Ma. Above 30 m of sediments occur two Igtertivâ Formation lava flows dated to 43.77 ± 1.08 Ma. The overlying sediments of the Bopladsdalen and Krabbedalen Formations are therefore not older than about 44 Ma and palynological evidence shows that they are also not much younger than this. Use of the Geological Time Scale 2012 has resulted in good agreement between radiometric and palynological ages. The Igtertivâ Formation lava flows were fed from a regional coast-parallel dyke swarm indicating a new rifting episode at 49–44 Ma. This coincides with a major mid-Eocene plate reorganisation event in the North Atlantic and the start of northward-propagation of the Reykjanes Ridge through the continent. The Igtertivâ rift may have been directly instrumental for the initiation of this process.

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A preliminary study of flow directions of Tertiary hyaloclastites and pahoehoe lava flows on Svartenhuk Halvø, West Greenland

Rapport Grønlands Geologiske Undersøgelse ◽

10.34194/rapggu.v105.7747 ◽

1981 ◽

Vol 105 ◽

pp. 28-32

Author(s):

J.G Larsen

Keyword(s):

Field Work ◽

Lava Flows ◽

West Greenland ◽

Source Areas ◽

Preliminary Study ◽

Flow Directions

Field work on Svartenhuk Halvø in connection with the 1:100 000 map was started in 1980 and a preIiminary description of the basalts is reported here. This work is a continuation of the mapping further south on Ubekendt Ejland (1:100 000 map sheet Igdlorssuit 71 V. 1 Syd, Larsen, in press). A brief summary of the basalts from Svartenhuk Halvø is given by Clarke & Pedersen (1976). The present work is concerned with the oIivine-rich basalts of the lower formation in which flow directions were deduced from foreset bedding in the hyaloclastites (cf. Fuller, 1931) and inclination of pipe amygdales in pahoehoe lava flows (cf. Du Toit, 1907; Waters, 1960; Schmincke, 1967). The aim was to locate the palaeoslope and source areas.

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Radiocarbon Dates for Lava Flows from Northeast Rift Zone of Mauna Loa Volcano, Hilo 7 1/2’ Quadrangle, Island of Hawaii

Radiocarbon ◽

10.1017/s0033822200044842 ◽

1989 ◽

Vol 31 (2) ◽

pp. 179-186 ◽

Cited By ~ 3

Author(s):

J M Buchanan-Banks ◽

J P Lockwood ◽

Meyer Rubin

Keyword(s):

Plant Material ◽

Rift Zone ◽

Field Work ◽

Lava Flows ◽

Topographic Maps ◽

The West ◽

Radiocarbon Dates ◽

Mauna Loa ◽

Recovery Techniques ◽

Geologic Map

Twenty-eight 14C analyses are reported for carbonized roots and other plant material collected from beneath 15 prehistoric lava flows erupted from the northeast rift zone (NERZ) of Mauna Loa Volcano (ML) utilizing the recovery techniques of Lockwood and Lipman (1980). Most samples were collected from the Hilo 7 1/2’ quadrangle during field work for a geologic map of that quadrangle (Buchanan-Banks, unpub data); a few sample sites are located in adjacent quadrangles: Piihonua to the west and Mountain View to the south. Altitudes are given in English units as well as metric to facilitate locating sites on USGS topographic maps.

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Volcanism on Gough Island: a revised stratigraphy

Geological Magazine ◽

10.1017/s0016756800009572 ◽

1988 ◽

Vol 125 (2) ◽

pp. 175-181 ◽

Cited By ~ 20

Author(s):

J. G. Maund ◽

D. C. Rex ◽

A. P. Le Roex ◽

D. L. Reid

Keyword(s):

Sea Level ◽

Volcanic Activity ◽

Field Work ◽

Lava Flows ◽

Volcanic Island ◽

Volcanic Stratigraphy ◽

Angular Unconformity ◽

Gough Island ◽

Dyke Intrusion ◽

Three Phases

AbstractRecent field work on Gough Island combined with K–Ar dating of the lavas requires revision of the age and volcanic stratigraphy. Four main periods of volcanic activity on the island are recognized. These comprise the eruption of the Older Basalt Group which ranges in age from 2.5 to 0.52 Ma, the intrusion of aegerine-augite trachyte plugs (0.8−0.47 Ma), voluminous trachyte extrusion (0.30–0.12 Ma) and finally to eruption of the Edinburgh Basalt (0.20–0.13 Ma).Within the Older Basalt Group three phases of activity can be recognized; the earliest involving the eruption of pillow basalts and hyaloclastites when the island emerged from below sea level. This was followed by subaerial as-type lava flows and also dyke intrusion (phase two) which probably contributed to forming a large shield-type volcanic island, which in turn supported the eruption and deposition of flat-lying flows on an angular unconformity (phase three). Intrusion of aegirine-augite trachyte plugs occurred concurrently with the latter stages of Older Basalt eruption. After a period of considerable erosion the voluminous trachyte lavas and pyroclastics were erupted. The Edinburgh Basalt, erupted in the vicinity of Edinburgh Peak, represents the youngest volcanic activity on the island.

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Effusive silicic volcanism in the Paraná Magmatic Province, South Brazil: Physico-chemical conditions of storage and eruption and considerations on the rheological behavior during emplacement

Journal of Volcanology and Geothermal Research ◽

10.1016/j.jvolgeores.2017.05.027 ◽

2018 ◽

Vol 355 ◽

pp. 115-135 ◽

Cited By ~ 10

Author(s):

L.A. Polo ◽

D. Giordano ◽

V.A. Janasi ◽

L.F. Guimarães

Keyword(s):

Rheological Behavior ◽

Silicic Volcanism ◽

Physico Chemical ◽

Chemical Conditions ◽

South Brazil

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New observations on the easternmost extension of the Gardar supracrustals (Eriksfjord Formation), South Greenland

Rapport Grønlands Geologiske Undersøgelse ◽

10.34194/rapggu.v125.7894 ◽

1985 ◽

Vol 125 ◽

pp. 64-66

Author(s):

L.M Larsen ◽

T Tukiainen

Keyword(s):

Major Part ◽

Field Work ◽

Lava Flows ◽

The West ◽

Variable Size ◽

Volcanic Breccia

During the 1984 field work in the Motzfeldt Centre of the Igaliko Complex, some of the remnants of the supracrustal rocks of the Eriksfjord Formation were investigated. These occur at several localities bordering the centre, and are also found as inclusions (roof rafts) of variable size within the syenites of the centre. These supracrustal rocks form the easternmost extension ofthe sandstones and lavas ofthe Eriksfjord Formation, the major part of which is found on the Narssaq peninsula to the west. Some of the easterly remnants were described by Emeleus & Harry (1970) who noted the occurrence ofsandstone and volcanic breccia, agglomerate and lava flows and described two small agglomerate-filled volcanic plugs. Our observations extend those of Emeleus & Harry (1970).

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