scholarly journals Dating late Holocene lava flows in Pico de Orizaba (Mexico) by means of in situ-produced cosmogenic 36Cl, lichenometry and dendrochronology

2018 ◽  
Vol 47 ◽  
pp. 93-106 ◽  
Author(s):  
Jesús Alcalá-Reygosa ◽  
David Palacios ◽  
Irene Schimmelpfennig ◽  
Lorenzo Vázquez-Selem ◽  
Leopoldo García-Sancho ◽  
...  
Keyword(s):  
Late Holocene ◽  
Lava Flows

Geology and geochronology of Inaccessible Island, South Atlantic

1992 ◽  
Vol 129 (1) ◽  
pp. 1-16 ◽  
Author(s):  
L. Chevallier ◽  
D. C. Rex ◽  
W. J. Verwoerd
Keyword(s):  
Rift Zone ◽  
Olivine Basalt ◽  
Lava Flows ◽  
Volcanic Centre ◽  
Mantle Sources ◽  
Land Sliding ◽  
Dyke Swarms ◽  
East West ◽  
Age Determinations

AbstractInaccessible Island is the eroded remnant of an extinct, comparatively small intraplate volcano dominated by flows of alkaline olivine basalt. The oldest stratigraphie unit is a hydrothermally altered basement of somewhat questionable early Pliocene (6.5 Ma) age. This is unconformably overlain by a volcanic superstructure built up during the last three million years. The two formations have different trace element signatures that may be attributed to different mantle sources. Boulders of gabbro are common but the presence of an in situ plutonic intrusion could not be confirmed. Their K-Ar age of 12.8 Ma may be spurious and their possible relationship with the volcano is uncertain. Reliable age determinations of 0.95–0.72 Ma were obtained on lava flows of the second volcanic stage, subdivided into four units or stratigraphie members. The latest unit consists of plugs, sills and flows of an evolved magma fraction (benmoreite and trachyte) of which benmoreite is considered to be the more voluminous. Several dyke swarms of different ages reveal the internal structure of the volcano. It is concluded that the main volcanic centre was located immediately offshore to the northwest and that the edifice was attached to an east–west volcanic rift zone. Apart from marine erosion, massive land-sliding probably took part in shaping the island and its submarine platform.

scholarly journals Geochronology of vegetation stages of south-east Baltic coast (Kaliningrad region) during the middle and Late Holocene

2011 ◽  
Vol 38 (2) ◽  
pp. 172-181 ◽  
Author(s):  
Khikmatulla Arslanov ◽  
Olga Druzhinina ◽  
Larisa Savelieva ◽  
Dmitry Subetto ◽  
Ivan Skhodnov ◽  
...  
Keyword(s):  
Late Holocene ◽  
Late Glacial ◽  
Natural Object ◽  
Raised Bog ◽  
Baltic Coast ◽  
Kaliningrad Region ◽  
Late Glacial And Holocene ◽  
Peat Formation ◽  
Middle And Late Holocene

Abstract The raised bog sediments that have been continuously accumulated over time represent the most suitable natural object which enables us to reconstruct Late Glacial and Holocene vegetation and palaeoclimates. Bog peat consists of organic carbon formed in situ. It contains moss, plant fragments and microfossils that are necessary for the study of palaeovegetation and palaeoclimate. However, a successful study of palaeoenvironment can be carried out on the basis of investigation of a great quantity of samples along the whole peatbog thickness. In the present paper, the authors present the results of palynological, botanical investigations and radiocarbon dating of 31 peat samples taken from the raised bog Velikoye, located in the eastern part of Kaliningrad Region. The data obtained have enabled us to reconstruct the palaeovegetation, reveal the evolution of the bog and determine rate of peat formation at different evolutional stages over the last 7500 cal BP.

Metallogenesis of the Abitibi greenstone belt of Canada: a contribution from the analysis of trace lead in sulfide minerals

1989 ◽  
Vol 26 (12) ◽  
pp. 2529-2540 ◽  
Author(s):  
Etienne Deloule ◽  
Clément Gariépy ◽  
Bernard Dupré
Keyword(s):  
Greenstone Belt ◽  
Igneous Rocks ◽  
Lava Flows ◽  
Ore Formation ◽  
Abitibi Greenstone Belt ◽  
Isotopic Compositions ◽  
Leaching Experiments ◽  
Iron Formations ◽  
Different Sources

Pb-isotopic compositions are reported for 12 ore localities within the late Archean Abitibi greenstone belt. The studied samples carry massive or disseminated sulfides hosted in a variety of materials, including mafic–ultramafic igneous rocks, felsic lavas, porphyries, and sedimentary iron formations. Repeated leaching experiments on these sulfides frequently revealed the presence of a radiogenic Pb component, which is attributed to in situ decay of U and Th. The leaching experiments make it possible, in some cases, to separate the radiogenic Pb from the initial Pb included in the minerals. Six Pb–Pb isochrons formed by the analyses on leachates and residues show little evidence of secondary perturbations and yield ages that are, within error, similar to those determined for the supracrustal assemblage. This implies that the ores were concentrated synchronously with the main phases of magmatic activity, close to 2.7 Ga.The initial isotopic compositions of the sulfide specimens point to the existence of two different sources of metals: (i) juvenile, mantle-derived igneous rocks and (ii) older recycled supracrustal series. Ore formation frequently involves mixing of metals from these two sources in variable proportions. The initial isotopic composition of these two reservoirs is best evaluated by examining the composition of sulfides associated with komatiitic lava flows and with sedimentary iron formations, respectively.

Late Holocene Sea-Level Changes in the Northwest Tuamotu Islands, French Polynesia

1986 ◽  
Vol 25 (3) ◽  
pp. 350-368 ◽  
Author(s):  
Paolo Antonio Pirazzoli ◽  
Lucien François Montaggioni
Keyword(s):  
Sea Level ◽  
Late Holocene ◽  
French Polynesia ◽  
Sea Level Changes ◽  
Human Settlements ◽  
Field Surveys ◽  
Mean Sea Level ◽  
Maximum Elevation ◽  
Holocene Sea Level

Field surveys of several sea-level indicators (exposed in situ reef framework, conglomerates, coral colonies and Tridacna shells in a growth position, sea-corrosion notches) carried out on six atolls from the NW Tuamotus (Mataiva, Rangiroa, Arutua, Kaukura, Apataki and Takapoto) and data from four subsurface boreholes drilled through Mataiva show that during the late Holocene mean sea level (MSL) reached a maximum elevation at approximately + 0.9 m. It remained above the present MSL from between 6000 and 5500 yr B.P. until at least 1200 yr B.P. Human settlements on the atolls were extremely unlikely and probably impossible throughout this time. The area investigated seems to have been tectonically quite stable during the late Holocene. A local curve of MSL variations may be representative of the regional eustatic pattern.

Cosmic ray exposure dating with in situ produced cosmogenic 3He: Results from young Hawaiian lava flows

1990 ◽  
Vol 97 (1-2) ◽  
pp. 177-189 ◽  
Author(s):  
Mark D. Kurz ◽  
Debra Colodner ◽  
Thomas W. Trull ◽  
Richard B. Moore ◽  
Keran O'Brien
Keyword(s):  
Cosmic Ray ◽  
Lava Flows ◽  
Exposure Dating ◽  
Hawaiian Lava

Continuous methane measurements from a late Holocene Greenland ice core: Atmospheric and in-situ signals

2013 ◽  
Vol 368 ◽  
pp. 9-19 ◽  
Author(s):  
Rachael H. Rhodes ◽  
Xavier Faïn ◽  
Christopher Stowasser ◽  
Thomas Blunier ◽  
Jérôme Chappellaz ◽  
...  
Keyword(s):  
Late Holocene ◽  
Ice Core

scholarly journals High temperature in-situ study of radiative properties of basaltic dry magmas

2020 ◽  
Author(s):  
Jonas Biren ◽  
Leire del Campo ◽  
Lionel Cosson ◽  
Hao Li ◽  
Aneta Slodczyk ◽  
...  
Keyword(s):  
Risk Mitigation ◽  
Spectral Emissivity ◽  
The Body ◽  
Lava Flows ◽  
Radiative Properties ◽  
Optical Measurements ◽  
Large Temperature ◽  
Rock Composition ◽  
Apparent Lack

<p>Temperature is a key parameter controlling the evolution of lava flows. The hazardous behavior of eruptions prevents direct measurements of hot magmatic bodies. Hence, the temperature of magma is mostly retrieved by using non-contact methods (ground-based or satellite-based thermal cameras) based on measuring the infrared (IR) emission flux (E) of the body [1]. These well-established techniques are however subjected to important errors, ±100 °C, related to surrounding environment [2], large temperature gradients of cooling lavas [3], constant changes in composition and texture and especially an apparent lack of radiative emission properties during the lava emplacement. Despite that reducing the uncertainties of environmental and thermal gradients when measuring E is ultimately challenging, our study aimed to minimizing the uncertainty in one of the critical hitherto poorly known oversimplified parameters [3,4,5] namely spectral emissivity. Therefore, we performed optical measurements at relevant magmatic temperatures (up to 1200 °C) of representative basaltic dry magmas (MORB, alkaline, calc-alkaline). Emissivity has been systematically determined over a wide spectral (400-15000 cm<sup>-1</sup>) and thermal range (from room up to 1200 °C) using a non-contact in situ IR emissivity apparatus [6]. SEM, EMPA and Raman spectroscopy techniques were also used in order to characterize and understand the complex radiative behavior of these natural magmatic compositions. Emissivity varies accordingly with temperature and wavenumber but our results also show that small changes in bulk-rock composition produce drastic changes in emissivity at given T, with iron content and its oxidation state being the main agents controlling this parameter. Appropriate emissivity values will then help to refine current field or (space) satellite IR monitoring data (i.e. Holuhraun 2014-2015, Iceland; [3]) and to implement the thermo-rheological models of lava flows [7] as to support hazard assessment and risk mitigation.</p><p><strong>References: </strong><strong>[1] </strong>Kolzenburg et al. 2017. Bull. Volc. 79:45. <strong>[2]</strong> Ball and Pinkerton 2006. J. Geophys.Res., 111. <strong>[3] </strong>Aufaristama et al. 2018. Remote Sens. 10, 151 <strong>[4] </strong>Harris, A. 2013: Cambridge University press. 728. <strong>[5] </strong>Rogic et al. 2019 Remote Sens. 2019, 11, 662 <strong>[6] </strong>De Sousa Meneses et al. 2015. Infrared Physics & Technology 69. <strong>[7]</strong> Ramsey et al. 2019. Annals of Geophysics, 62, 2.</p><p> </p><p><strong>Keywords: </strong>Emissivity, temperature, vibrational spectroscopy, remote sensing, basalt</p>

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