Nouvelles donnees sur les diabases-porphyrites de la region de Sangineto (Calabre)

1961 ◽  
Vol S7-III (4) ◽  
pp. 370-378 ◽  
Author(s):  
Jean Claude Bousquet
Keyword(s):  
Volcanic Rocks ◽  
Pillow Lava ◽  
Lava Flows ◽  
Submarine Lava

Abstract The northernmost outcrop of the diabase-porphyrite complex of Calabria, Italy, is in the Sangineto zone, long recognized as exceptionally complex. Results of studies are reported whose particular purpose was to define the upper and lower boundaries of the series of diabases and porphyrites, to describe the interrelationships of the varieties within the series, and to ascertain the relationships of these rocks to the nonvolcanic country rocks. Pillow lava structures recognized in many places suggest that the volcanic rocks are ancient submarine lava flows. Overlying limestones contain layers of breccia in which Tithinian (Jurassic) fragments have been identified, thus refuting the Triassic age previously assigned to them in the literature.

Volcanoes geological mapping and structural geology with UAS High Resolution Digital Terrain Model : the Kuei-Shan Tao case example (Eastern Taiwan).

2021 ◽  
Author(s):  
Benoit Deffontaines ◽  
Kuo-Jen Chang ◽  
Samuel Magalhaes ◽  
Gérardo Fortunato
Keyword(s):  
High Resolution ◽  
Okinawa Trough ◽  
Volcanic Rocks ◽  
Digital Terrain Model ◽  
Structural Features ◽  
Point Of View ◽  
Geological Mapping ◽  
Lava Flows ◽  
Aerial Photographs ◽  
Structural Scheme

<p>Volcanic areas in the World are often difficult to map especially in a structural point of view as (1) fault planes are generally covered and filled by more recent lava flows and (2) volcanic rocks have very few tectonic striations. Kuei-Shan Tao (11km from Ilan Plain – NE Taiwan) is a volcanic island, located at the soutwestern tip of the South Okinawa trough (SWOT). Two incompatible geological maps had been already published both lacking faults and structural features (Hsu, 1963 and Chiu et al., 2010). We propose herein not only to up-date the Kuei-Shan Tao geological map with our high resolution dataset, but also to create the Kuei-Shan Tao structural scheme in order to better understand its geological and tectonic history.</p><p>Consequently, we first acquired aerial photographs from our UAS survey and get our new UAS high resolution DTM (HR UAS-DTM hereafter) with a ground resolution <10cm processed through classical photogrammetric methods. Taking into account common sense geomorphic and structural interpretation and reasoning deduced form our HR UAS-DTM, and the outcropping lithologies situated all along the shoreline, we have up-dated the Kuei-Shan Tao geological mapping and its major structures. To conclude, the lithologies (andesitic lava flows and pyroclastic falls) and the new structural scheme lead us to propose a scenario for both the construction as well as the dismantling of Kuei-Shan Tao which are keys for both geology and geodynamics of the SWOT.</p>

scholarly journals Trace-Element and Pb Isotope Evidence on Extracting Sulfides from Potassic Melts beneath Longmenshan and Molabushan Volcanoes, Wudalianchi, Northeast China

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 319 ◽  
Author(s):  
Sergei Rasskazov ◽  
Yi-Min Sun ◽  
Irina Chuvashova ◽  
Tatyana Yasnygina ◽  
Chen Yang ◽  
...  
Keyword(s):  
Trace Element ◽  
Volcanic Rocks ◽  
Volcanic Field ◽  
Lava Flows ◽  
Pb Isotope ◽  
Linear Pattern ◽  
Wide Range ◽  
Mantle Sources ◽  
Isotope Evidence ◽  
Isotope Study

In the Wudalianchi volcanic field, eruptions started with low-Mg potassic lava flows 2.5–2.0 Ma ago and later changed to both low- and moderate-Mg potassic compositions. Volcanic rocks from the Molabushan and Longmenshan volcanoes record an unusually wide range of Pb abundances (from 3.7 ppm to 21 ppm relative to predominant range of 10–15 ppm). To determine the cause of these, we performed a comparative trace-element and Pb isotope study of rocks from these volcanoes and older lava flows. On a uranogenic lead diagram, older low-Mg lavas from lithospheric mantle sources plot on a secondary isochron with a slope corresponding to an age of 1.88 Ga. This contrasts with moderate-Mg volcanic rocks from the Molabushan cone, interpreted to have been derived from a recent convective mantle source, which define a flat linear pattern. Low-Mg rocks from the Molabushan flow have lead isotopic compositions that indicate mixed Gelaqiu and Molabu sources. Relative to rocks from the Molabushan cone, moderate-Mg lavas and slags from the East Longmenshan volcano have modified compositions characterized by Pb, S, and Ni abundances, Ni/Co, Ni/MgO ratios as well as 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, Ce/Pb, Th/Pb, and U/Pb ratios. We infer that the older Wudalianchi magmas were likely derived from a Paleoproterozoic lithospheric fragment, related to the evolved primordial mantle, and that later magmas were generated in the convecting mantle. These were influenced by segregation of small amounts of sulfides.

Raman spectroscopy of volcanic lavas and inclusions of relevance to astrobiological exploration

2010 ◽  
Vol 368 (1922) ◽  
pp. 3127-3135 ◽  
Author(s):  
Susana E. Jorge-Villar ◽  
Howell G. M. Edwards
Keyword(s):  
Volcanic Rocks ◽  
Volcanic Eruptions ◽  
Active Volcano ◽  
Spectroscopic Studies ◽  
Lava Flows ◽  
Pyroclastic Flows ◽  
Raman Spectroscopic ◽  
Normal Expectation ◽  
Terrestrial Environments ◽  
Volcanic Lava

Volcanic eruptions and lava flows comprise one of the most highly stressed terrestrial environments for the survival of biological organisms; the destruction of botanical and biological colonies by molten lava, pyroclastic flows, lahars, poisonous gas emissions and the deposition of highly toxic materials from fumaroles is the normal expectation from such events. However, the role of lichens and cyanobacteria in the earlier colonization of volcanic lava outcrops has now been recognized. In this paper, we build upon earlier Raman spectroscopic studies on extremophilic colonies in old lava flows to assess the potential of finding evidence of biological colonization in more recent lava deposits that would inform, first, the new colonization of these rocks and also provide evidence for the relict presence of biological colonies that existed before the volcanism occurred and were engulfed by the lava. In this research, samples were collected from a recent expedition to the active volcano at Kilauea, Hawaii, which comprises very recent lava flows, active fumaroles and volcanic rocks that had broken through to the ocean and had engulfed a coral reef. The Raman spectra indicated that biological and geobiological signatures could be identified in the presence of geological matrices, which is encouraging for the planned exploration of Mars, where it is believed that there is evidence of an active volcanism that perhaps could have preserved traces of biological activity that once existed on the planet’s surface, especially in sites near the old Martian oceans.

Physical volcanology of the footwall rocks near the Mattabi massive sulphide deposit, Sturgeon Lake, Ontario

1988 ◽  
Vol 25 (2) ◽  
pp. 280-291 ◽  
Author(s):  
D. A. Groves ◽  
R. L. Morton ◽  
J. M. Franklin
Keyword(s):  
Repetitive Sequences ◽  
Volcanic Rocks ◽  
Massive Sulphide ◽  
Lava Flows ◽  
Pyroclastic Flows ◽  
Lake Area ◽  
Massive Sulphide Deposit ◽  
Sulphide Deposit ◽  
Water Influx ◽  
Felsic Lava

Subaerial and shallow subaqueous mafic hyalotuffs, lava flows, and flow breccias, felsic lava flows, and pyroclastic flows and falls form a 2 km thick succession beneath the Mattabi massive sulphide deposit. The lowermost 800 m of section comprises massive to amygdaloidal mafic flows and flow breccias interlayered with repetitive sequences of thinly bedded felsic tuff: pillow lavas and hyaloclastites are absent. Amygdaloidal felsic lavas overlie the mafic flows and are locally capped by coarse explosion breccia. This breccia is believed to represent the start of mafic hydrovolcanism, which produced ash falls, surges, and flows. These pyroclastic deposits formed thin- to thick-bedded hyalotuffs that contain highly vesicular and quenched juvenile and accessory lithic fragments. Periods of water influx probably led to the construction of a tuff cone, which represents a submergent hydrovolcanic cycle.In the Mattabi area, pyroclastic flow deposits form the immediate mine footwall strata and include (i) massive basal beds and overlying bedded ash tuffs and (ii) massive pumiceous units. These deposits overlie and, to the west in the Darkwater Lake area, are intercalated with the mafic hyalotuff sequence. The morphology of the footwall volcanic rocks indicates that the Mattabi and the F-zone massive sulphide deposits formed in a shallow subaqueous environment.

The flow of basalt lava from air into water – its structural expression and stratigraphic significance

1970 ◽  
Vol 107 (1) ◽  
pp. 13-19 ◽  
Author(s):  
J. G. Jones ◽  
P. H. H. Nelson
Keyword(s):  
Pillow Lava ◽  
Lava Flows ◽  
Basalt Lava ◽  
Volcanic Pile

SummaryWhen basalt lava flows from air into water it leaves a distinctive record of the waterlevel of the time in the form of lava sheets overlying and passing down into vitric breccia and/or pillow lava. Relative movements of waterlevel and a volcanic pile or terrain over a period of time may be readily deciphered from such records.

Constraints on the formation of submarine lava flows from numerical model calculations

1999 ◽  
Vol 92 (3-4) ◽  
pp. 215-229 ◽  
Author(s):  
F. Klingelhöfer ◽  
M. Hort ◽  
H.-J. Kümpel ◽  
H.-U. Schmincke
Keyword(s):  
Numerical Model ◽  
Lava Flows ◽  
Model Calculations ◽  
Submarine Lava

The Mings Bight Ophiolite Complex, Newfoundland: Appalachian oceanic crust and mantle

1978 ◽  
Vol 15 (5) ◽  
pp. 781-804 ◽  
Author(s):  
W. S. F. Kidd ◽  
John F. Dewey ◽  
John M. Bird
Keyword(s):  
Volcanic Rocks ◽  
Pillow Lava ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Ophiolite Complex ◽  
Pillow Lavas ◽  
Late Cambrian ◽  
Head Formation ◽  
Lava Sequence ◽  
Thrust Sheets

The Mings Bight Ophiolite Complex, of probable early Ordovician age, is disposed in four major thrust sheets with an eastward vergence at the northern end of the Baie Verte Lineament. This narrow ophiolitic belt, and (to the south) an adjacent zone of early Devonian volcanic rocks and sediments, were affected by a strong Acadian (Middle Devonian?) deformation between more resistant blocks consisting mainly of rocks that were deformed and regionally metamorphosed, prior to the development of the ophiolites and overlying mafic sediments and volcanic rocks, probably in Late Cambrian to earliest Ordovician. The ophiolite sequence and conformably overlying sedimentary and volcanic sequence define an overturned synclinal structure with an eastward vergence; the three western thrust sheets contain an inverted sequence, the eastern sheet is upright. The thick mafic volcaniclastic and pillow lava sequence overlying the ophiolite complex suggests that the ophiolite complex was generated as the the floor of a small rear-arc or intra-arc basin. The ophiolite complex, although dissected by faults, consists of an ordered sequence from non-cumulate tectonite harzburgite through cumulate ultramafic rocks, gabbro and sheeted dike complex to pillow lavas. The continuous, coastal exposures show the relationships between the lithologies of the ophiolite complex unusually clearly, and these are described in some detail. In particular, the relationships between the sheeted dikes and both the homogeneous upper gabbro and the pillow lavas, and the intrusive complexities and the high-temperature deformation in the layered gabbros and ultramafics, are very clearly displayed. An ocean floor fault containing diapiric serpentinite is preserved in one thrust sheet. Two new formations are proposed, for the mafic volcaniclastic sediments (Big Head Formation) and for the overlying pillow lavas (Barry–Cunningham Formation) above the ophiolite complex.

scholarly journals The Petrogenesis of Mid-Cretaceous Continental  Intraplate Volcanism in Marlborough, New Zealand,  during the Break-up of Gondwana

2021 ◽  
Author(s):  
◽  
Alexander Joseph McCoy-West
Keyword(s):  
New Zealand ◽  
Lithospheric Mantle ◽  
Volcanic Rocks ◽  
Oceanic Lithosphere ◽  
Small Degree ◽  
Lava Flows ◽  
Dyke Swarm ◽  
Subcontinental Lithospheric Mantle ◽  
Igneous Complex ◽  
Volcanic Material

<p>The Lookout Volcanics are the remnants of an extensive sheet of mid-Cretaceous (ca. 96 Ma) continental intraplate volcanic rocks erupted just prior to the rifting of New Zealand from Gondwana. Preserved in a fault angle depression bounded by the Awatere Fault located in Marlborough, South Island, New Zealand, the volcanic rocks cover an area of ca. 50 km2 with exposed thicknesses up to 1000 m. On the basis of stratigraphic evidence the dominantly terrestrial lavas flows are inferred to have erupted from dykes of a coeval radial dyke swarm. A detailed sampling of the lava flows of the Lookout Volcanics has been undertaken with a ca. 700 m composite stratigraphic section being constructed, largely based on a continuous sequence of lava flows outcropping in Middlehurst Stream. New Rb-Sr age constraints for the Lookout Volcanics (97.6 plus or minus 3.4 Ma) and Blue Mountain Igneous Complex (97.1 plus or minus 0.7 Ma) are consistent with previous radiometric dates of plutonic complexes in the Central Marlborough Igneous Complex, and suggest a rapid accumulation of volcanic material from ca. 98-96 Ma during the initial extension of proto-New Zealand. The predominantly mafic and alkaline samples include basalt, picrobasalt, basanite, trachybasalt and basaltic trachyandesite rock types. No samples represent primary magmas with all samples having undergone fractionation (or accumulation) of olivine plus clinopyroxene plus or minus plagioclase plus or minus Fe-Ti oxides. Initial Sr-Nd-Hf-Pb isotopic variations (87Sr/86Sr = 0.7030-0.7039; 143Nd/144Nd = 0.51272-0.51264; 176Hf/177Hf = 0.28283-0.28278; 206Pb/204Pb = 20.32-18.82) reflect mixing between melts of a HIMUlike mantle component with up to 25-30% of an Early Cretaceous upper crustal component. Oxygen isotope ratios determined by laser fluorination analysis from 6 lava flows yielded delta 18O = 4.7-5.0 per thousand for olivine, 4.8-5.4 per thousand in clinopyroxene cores, 3.9-5.5 per thousand in clinopyroxene rims. Average olivine (4.8 per thousand) and clinopyroxene core (5.1 per thousand) values are 0.4-0.5 per thousand lower than those of average mantle peridotite but comparable to those of HIMU OIB, and are consistent with New Zealand intraplate magmas being generated by a low delta 18O mantle. However, oxygen isotopic disequilibrium between clinopyroxene cores and rims (Delta 18O = -1.4 to +0.3) records the overprinting of this signature by crustal processes. Negative disequilibrium between clinopyroxene rims and cores in primitive samples suggests these phenocrysts grew in a shallow crustal magma chamber with an active meteoric water system. The effects of crustal assimilation can also be observed with clinopyroxene phenocrysts from the most evolved sample exhibiting coupled elevated delta 18O and 87Sr/86Sr. Variations in incompatible trace element ratios are consistent with the Lookout Volcanics being the small degree (2-5%) partial melts of an amphibole-bearing garnet pyroxenite. Furthermore, the elevated NiO contents of olivine phenocrysts are consistent with melting of a pyroxenitic mantle source. The presence of residual amphibole constrains melting to the hydrous subcontinental lithospheric mantle. The Lookout Volcanics and coeval plutonic complexes are the oldest occurrences of HIMU magmatism in Zealandia. This source was generated by small degree silicate melts from recycled oceanic lithosphere that metasomatised the base of the subcontinental lithospheric mantle beneath East Gondwana over 200 Ma ago.</p>

scholarly journals Late Miocene transcurrent tectonics in NW Turkey: evidence from palaeomagnetism and 40Ar–39Ar dating of alkaline volcanic rocks

2007 ◽  
Vol 144 (2) ◽  
pp. 379-392 ◽  
Author(s):  
N. KAYMAKCI ◽  
E. ALDANMAZ ◽  
C. LANGEREIS ◽  
T. L. SPELL ◽  
O. F. GURER ◽  
...  
Keyword(s):  
Fault Zone ◽  
Late Miocene ◽  
Active Faults ◽  
Volcanic Rocks ◽  
Volcanic Eruptions ◽  
North Anatolian Fault ◽  
Lava Flows ◽  
North Anatolian Fault Zone ◽  
The North ◽  
Nw Turkey

A number of intra-continental alkaline volcanic sequences in NW Turkey were emplaced along localized extensional gaps within dextral strike-slip fault zones prior to the initiation of the North Anatolian Fault Zone. This study presents new palaeomagnetic and 40Ar–39Ar geochronological results from the lava flows of NW Turkey as a contribution towards understanding the Neogene–Quaternary tectonic evolution of the region and possible roles of block rotations in the kinematic history of the region. 40Ar–39Ar analyses of basalt groundmass indicate that the major volume of alkaline lavas of NW Turkey spans about 4 million years of episodic volcanic activity. Palaeomagnetic results reveal clockwise rotations as high as 73° in Thrace and 33° anticlockwise rotations in the Biga Peninsula. Movement of some of the faults delimiting the areas of lava flows and the timing of volcanic eruptions are both older than the initiation age of the North Anatolian Fault Zone, implying that the region experienced transcurrent tectonics during Late Miocene to Pliocene times and that some of the presently active faults in the region are reactivated pre-existing structures.

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