Geochronological constraints on the Late Proterozoic to Cambrian crustal evolution of eastern Dronning Maud Land, East Antarctica: a synthesis of SHRIMP U-Pb age and Nd model age data

2008 ◽  
Vol 308 (1) ◽  
pp. 21-67 ◽  
Author(s):  
Kazuyuki Shiraishi ◽  
Daniel J. Dunkley ◽  
Tomokazu Hokada ◽  
C. Mark Fanning ◽  
Hiroo Kagami ◽  
...  
1990 ◽  
Vol 8 (2) ◽  
pp. 99-126 ◽  
Author(s):  
Y. Ohta ◽  
B. O. Tørudbakken ◽  
K. Shiraishi

1997 ◽  
Vol 9 (1) ◽  
pp. 43-45 ◽  
Author(s):  
U. Wand ◽  
G. Schwarz ◽  
E. Brüggemann ◽  
K. Bräuer

Lake Untersee is the largest freshwater lake in the interior of East Antarctica. It is a perennially ice-covered, max. 169 m deep, ultra-oligotrophic lake. In contrast to earlier studies, we found clear evidence for physical and chemical stratification in the summer of 1991–92. However, the stratification was restricted to a trough, c. 500 m wide and up to 105 m deep, in the south-western part of the lake. There, the water body was distinctly stratified as indicated by sharp vertical gradients of temperature, pH, dissolved oxygen, and electrical conductivity. The water column was anoxic below 80 m. The chemical stratification is also indicated by changes of ionic ratios. Moreover, there was some evidence for methanogenesis and bacterial sulphate reduction in Lake Untersee.


2021 ◽  
Author(s):  
Sotaro Baba ◽  
Kenji Horie ◽  
Tomokazu Hokada ◽  
Mami Takehara ◽  
Atsushi Kamei ◽  
...  

2021 ◽  
Author(s):  
Nadezda Sushchevskaya ◽  
German Leitchenkov ◽  
Boris Belyatsky

<p>The Mesozoic Karoo-Maud and Kerguelen plumes had a significant influence on Gondwana and the oceanic lithosphere. Jurassic magmatism, formed under the influence of a huge Karoo plume at 184–178 Ma ago, covered large areas of the Dronning Maud Land in East Antarctica. Later, 130 – 0 m.y. ago, under the influence of the Kerguelen plume, magmatism formed in the area of the Lambert glacier, and the Gaussberg volcano (Quaternary time) appeared, located on the coast opposite the Kerguelen archipelago. We assume that the Karoo mantle plume initiated the formation of a “mega-apophyses” from the main plume manifestation area within the Karoo province in the southeastern African continet (ca. 2000 km in diameter). These mega-apophyses are represented by the Ferrar Igneous Province (ca. 3000 km long area of intrusive activity along the Transantarctic Mountains) and a supposed igneous province (ca. 1500 km long) covering the East Antarctic coast between the Lazarev and Cosmonauts Seas. Based on petrological and geochemical studies, the characteristic features of magmas of the Karoo, Dronning Maud Land, and Ferrar igneous provinces have been determined, which indicate that for all magmas associated with Karoo and Kerguelen plumes, the main source of melt enrichment is a mantle source with characteristics of the EM-II component (most typically for magmas of the Ferrar Province). It reflects the properties of an enriched, fluid-rich, ancient continental mantle, metasomatized at the early stages of the tectonic development of the region and involved in the melting process. A rarer admixture of the ancient lithospheric component (EM-I, with <sup>206</sup>Pb/<sup>204</sup>Pb = 16.5 and <sup>143</sup>Nd/<sup>144</sup>Nd = 0.5122) was revealed in both plumes. The existence of mantle plumes in the Southern Hemisphere and their long-term development had a significant impact on the structure and evolution of the East Antarctica.</p>


Antarctica ◽  
2006 ◽  
pp. 45-54 ◽  
Author(s):  
Mervin J. D’Souza ◽  
A. V. Keshava Prasad ◽  
Rasik Ravindra

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