scholarly journals Detection of Late Pleistocene tephras and cryptotephras using major element chemistry of glass shards from Chikyu C9001C cores, NW Pacific Ocean

2018 ◽  
Vol 26 (0) ◽  
pp. 1-20 ◽  
Author(s):  
Tabito Matsu'ura ◽  
Junko Komatsubara
Keyword(s):  
Pacific Ocean ◽  
Late Pleistocene ◽  
Major Element ◽  
Major Element Chemistry ◽  
Element Chemistry ◽  
Glass Shards

Major element chemistry of the geothermal sea-water at Reykjanes and Svartsengi, Iceland

1978 ◽  
Vol 42 (322) ◽  
pp. 209-220 ◽  
Author(s):  
Stefán Arnórsson
Keyword(s):  
Ground Water ◽  
Major Element ◽  
Sea Water ◽  
Geothermal Water ◽  
Ionic Exchange ◽  
Geothermal Waters ◽  
Major Element Chemistry ◽  
Element Chemistry ◽  
Geothermal Fields ◽  
Reykjanes Peninsula

SummaryHigh-temperature geothermal fields in Iceland represent localized anomalies of hot, altered rock in the uppermost part of the crust, which coincide with points of maximum tectonic/magmatic activity. These points correspond to the intersection of oblique fault swarms to the plate boundaries. Geothermal activity under mid-ocean ridges follows probably similar tectonic/magmatic anomalies.Due to high permeability sea-water invades the bed-rock of the Reykjanes Peninsula, Iceland, and is overlain by a variably thick lens of dilute ground water of meteoric origin. The variable degree of salinity of geothermal waters in the Reykjanes Peninsula has resulted from different degree of mixing of fresh ground water with the underlying sea-water-ground-water in the downflow zones around the geothermal fields. At Reykjanes the geothermal water represents heated sea-water without any freshwater mixing. The difference in the composition of sea-water or sea-water/fresh water mixtures and the geothermal waters is due to basalt/water interaction at elevated temperatures. The major-element chemistry of the geothermal water represents an equilibrium composition at the relevant aquifer temperatures. The activities of silica, calcium, sulphate, and carbonate are thus limited by the solubilities of quartz, anhydrite, and calcite. Fluoride activity is thought to be controlled by an ionic exchange reaction where it substitutes for hydroxyl groups in phyllosilicates. The ratios of individual cations and hydrogen ion are governed by ionic exchange equilibria with hydrothermal minerals, probably smectite and chlorite. The equilibrium pH for the Reykjanes and Svartsengi geothermal waters is 5·5 and 5·1 respectively. Sea-water will become somewhat acid upon heating to more than about 300 °C and equilibration with basalt, the acidity increasing with temperature.

Determination of major element chemistry in terrestrial waters from Antarctica by ion chromatography

1996 ◽  
Vol 739 (1-2) ◽  
pp. 257-263 ◽  
Author(s):  
K.A Welch ◽  
W.B Lyons ◽  
E Graham ◽  
K Neumann ◽  
J.M Thomas ◽  
...  
Keyword(s):  
Ion Chromatography ◽  
Major Element ◽  
Major Element Chemistry ◽  
Element Chemistry

scholarly journals AMS 14C Dates and Major Element Composition of Glass Shards of Late Pleistocene Tephras on Tanegashima Island, Southern Japan

Radiocarbon ◽  
2012 ◽  
Vol 54 (3-4) ◽  
pp. 351-358 ◽  
Author(s):  
Mitsuru Okuno ◽  
Masayuki Torii ◽  
Hideto Naruo ◽  
Yoko Saito-Kokubu ◽  
Tetsuo Kobayashi
Keyword(s):  
Late Pleistocene ◽  
Major Element ◽  
Volcanic Glass ◽  
Archaeological Site ◽  
Major Element Composition ◽  
Ams Radiocarbon Dating ◽  
Southern Japan ◽  
Tephra Layers ◽  
C 32 ◽  
Glass Shards

Four late Pleistocene tephra layers—Tane I (Tn1), II (Tn2), III (Tn3), and IV (Tn4) in ascending order—are intercalated between widespread tephras, Kikai-Tozurahara (K-Tz: 95 ka) and Aira-Tn (AT: 30 cal kBP), on Tanegashima Island, in southern Japan. Paleolithic ruins such as the Yokomine C and Tatikiri archaeological sites were excavated from the loam layer between the Tn4 and Tn3 tephras. To refine the chronological framework on the island, we conducted accelerator mass spectrometry (AMS) radiocarbon dating for 2 paleosol and 6 charcoal samples related with the late Pleistocene tephras and the Yokomine C archaeological site. The obtained 14C dates are consistent with the stratigraphy in calendar years, 33 cal kBP for Tn4, 40 cal kBP for Tn3, and >50 cal kBP for Tn2 and Tn1. The charcoal dates from Yokomine C, 32–38 cal kBP, not only constrain the age of Tn4 and Tn3 ashes, but also serve as a possible date for the site. We also measured the major element compositions of volcanic glass shards with EDS-EPMA to characterize these tephras. Although we could not find a possible correlative for Tn3 and Tn4 ashes using major element oxides of the glass shards, i.e. 75–76 wt% in SiO2, the glass chemistry obtained in this study will be valuable in correlating these tephras with their source volcanoes in the near future.

Geologic control of Sr and major element chemistry in Himalayan Rivers, Nepal

2000 ◽  
Vol 64 (15) ◽  
pp. 2549-2566 ◽  
Author(s):  
N.B. English ◽  
J. Quade ◽  
P.G. DeCelles ◽  
C.N. Garzione
Keyword(s):  
Major Element ◽  
Major Element Chemistry ◽  
Element Chemistry ◽  
Himalayan Rivers
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