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Ravindra, R.
- Landscape Evaluation of Humboldt and Adjacent Areas, Wohlthat Mountains, East Antarctica
Authors
1 Geological Survey of India, Antarctica Division, Faridabad, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 37, No 2 (1991), Pagination: 172-183Abstract
The Humboldt region of the Wohlthat Mountains in East Antarctica, depicts both polar and alpine type of morphological set-up. While the former is represented by vast stretch of antarctic ice sheet with hills and nunataks, the latter is marked by glacially fretted uplands with cirques, aretes, horns and moraines. These and other landforms associated with denudation and depositional processes have been used to evaluate the regional landscape of Humboldt area, which conforms with the composite erosional landscape of Sugden and John (1976).The glacial geomorphological features are largely, due to Somovken and Humboldt glaciers flowing on either side of the Humboldt fiat. The interference of the movement between the two glaciers is reflected in the depositional pattern of moraines. The polar ice evidently covered much greater portions of the area in the past with ice level covering the ridges at 1900 m - 2000 m above sea level.
Keywords
Geomorphology, Antarctica, Wohlthat Mountains.
- Petrology and Geochemistry of the Grubergebirge Anorthosite and Marginal Rocks, Central Dronning Maud Land: Further Characterization of the Late Neoproterozoic Magmatic Event in East Antarctica
Authors
1 Geochronology and Isotope Geology Division, Geological Survey of India, 15 A&B Kyd Street, Kolkata – 700 016, IN
2 Antarctica Division, Geological Survey of India, NH-5P, NIT, Faridabad - 121001, IN
3 Airborne Mineral and Surveys and Exploration Wing, WR, Geological Survey of India, Jhalana Dungri, Jaipur, IN
4 National Centre for Antarctic and Ocean Research, Headland Sada, Vasco-da-Gama, Goa - 403 004, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 78, No 1 (2011), Pagination: 7-18Abstract
The Grubergebirge anorthosite, a Late Neoproterozoic massif-type anorthosite, was emplaced into Late Mesoproterozoic-aged metamorphosed orthogneisses and supracrustal rocks in the Wohlthat Mountains. Mineralogically and chemically, the marginal rocks to the anorthosite massif classify as ferromonzodiorite and ferromonzonite.
Variations in trace and rare earth element abundances and normalized patterns between the anorthosite and associated marginal ferromonzodiorite (and minor ferromonzonite) and distinct differences between the ferromonzodiorite and ferromonzonite have been observed. Whereas the magmas from which the anorthosite crystallized have been slightly contaminated by incorporating crustal material (now occurring as enclaves), the marginal ferromonzodiorite represent rocks that originated due to mixing (hybridization) of injected primitive ferrodiorite magma(s) with preexisting crustal material, resulting in the hybrid ferromonzodiorite.
These events at the margin of the massif anorthosite represent a widespread Late Neoproterozoic magmatic event with accompanying crustal mixing; all these rocks were thereafter metamorphosed under amphibolite- to granulite-facies conditions during the Early Cambrian Period. In contrast, unmetamorphosed dykes with a ferrodiorite mineralogy, of Late Cambro-Ordovician age, have been found that probably represent a part of the late magmatic suites of the south Petermannketten (Zwiesel).