Results 181 to 190 of about 3,256 (202)

Mesoproterozoic anorogenic magmatism in southern Norway

Geological Society, London, Special Publications, 1996
Abstract The 1500 Ma Rjukan Group of the Telemark Supracrustal Suite, south Norway, consists of a metamorphosed sequence of acid volcanic rocks (Tuddal Formation) overlain by a comparable thickness of metabasalts (Vemork Formation). Both acid and basic volcanic rocks have within-plate chemical compositions.
J. F. Menuge, T. S. Brewer
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The Mesoproterozoic – no “boring billion”

2019
The authors show that the Mesoproterozoic (1.6-1.0 bn year before present) was no “boring billion” but a “bustling billion” - not only with Stromatolites and their apex in the Calymmian and Ectasian but also with the presence of multicellular organisms. To make it visible a graphical reconstruction was created.
Troppenz, UweM., Littkowski, Sven
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Configuration of Columbia, a Mesoproterozoic Supercontinent

Gondwana Research, 2002
Abstract A supercontinent, here named Columbia, may have contained nearly all of the earth's continental blocks at some time between 1.9 Ga and 1.5 Ga. At that time, eastern India, Australia, and attached parts of Antarctica were apparently sutured to western North America, and the eastern margin of North America, southern margin of Baltica/North ...
John J.W. Rogers, M. Santosh
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Lithostratigraphy of the Mesoproterozoic Jannelsepan Formation

South African Journal of Geology, 2017
The Jannelsepan Formation forms part of the 1.30 to 1.24 Ga Areachap Group. It is a pre-tectonic calc-alkaline volcano-sedimentary unit in the 1.2 to 1.0 Ga Namaqua Sector of the Namaqua-Natal Metamorphic Province. The main rock types are amphibolites with subordinate clinopyroxene or biotite.
H. Minnaar, D.H. Cornell, R.H. Bailie
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Lithostratigraphy of the Mesoproterozoic Garies Granite

South African Journal of Geology, 2016
The Garies Granite is a mesocratic to leucocratic, porphyritic post-tectonic member of the Spektakel Suite in the Mesoproterozoic Namaqua-Natal Belt of western Namaqualand. It is a composite unit, showing a continuum of rock types from mesocratic porphyritic biotite granite with characteristic slender phenocrysts (Rooiberg-type) to coarse-grained ...
C.H. de Beer, P.H. Macey
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Mesoproterozoic Eastern Ghat Mobile Belt

2015
The rugged country with discontinuous hill ranges facing the Bay of Bengal is known as the Eastern Ghat. The average altitude is 610 m, and the tallest peak Mahendragiri is 1501 m high. Extending from Brahmani River in Odisha to Ongole in southeastern Andhra Pradesh, the terrane of highly deformed rocks that experienced ultrahigh-temperature granulite ...
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Paleomagnetism of Mesoproterozoic Satakunta sandstone, Western Finland

Precambrian Research, 2014
Abstract A paleomagnetic study of the Mesoproterozoic Satakunta sandstone formation, Western Finland is presented here. Two components of natural remanent magnetization (NRM) were isolated in the sandstone with alternating field (AF) and thermal demagnetization treatments.
R. Klein, L.J. Pesonen, J. Salminen, S. Mertanen   +3 more
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Vindhyan Akinites: An Indicator of Mesoproterozoic Biospheric Evolution

Origins of Life and Evolution of Biospheres, 2005
A wide size range of rod-shaped, ellipsoidal akinites assignable to Archaeoellipsoides are reported from the Newari locality of the Mesoproterozoic Kheinjua Formation of the Semri Group, Vindhyan Supergroup. These akinites of heterocystous cyanobacteria (Archaeoellipsoides) represent the smallest of the forms reported from any other assemblage to date ...
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Sunspot cycles recorded in Mesoproterozoic carbonate biolaminites

Precambrian Research, 2014
Abstract Well-preserved carbonate biolaminites from the early Mesoproterozoic Wumishan Formation (ca. 1.5–1.45 Ga) of North China show submillimeter-scale yearly couplets that consist of alternating dark and light laminae, and are texturally similar to those reported from Holocene tufas.
Dongjie Tang, Xiaoying Shi, Ganqing Jiang   +2 more
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Mesoproterozoic Borden Basin, northern Baffin Island

2022
The unmetamorphosed and nearly undeformed late Mesoproterozoic Borden Basin on northern Baffin Island exhibits sag, rift, and foreland-basin-like phases. A thin, partly subaqueous basal basalt is overlain by mature shallow-marine quartz arenite, upward-deepening siltstone and shale (marking the beginning of rifting), a complex suite of rift-delineated ...
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