Results 41 to 50 of about 17,986 (209)

ISOTOPIC-GEOCHEMICAL ASPECTS OF THE OCCURRENCE OF LIFE ON EARTH IN THE EARLY PRECAMBRIAN

Геохімія техногенезу
The time of the appearance of life and oxygen on Earth is debatable. In order to search for signs of the presence of life and the evolution of the Earth’s outer shells, in particular the time of the appearance of oxygen in the atmosphere,
Demikhov Yu.M., Verkhovtsev V.G., Musich O.G., Borisova N.M., Kravchuk Z.N   +4 more
doaj   +1 more source

The early Proterozoic Saari-Kiekki greenstone belt: A representative of the Sariola Group at Kuhmo, Eastern Finland [PDF]

Bulletin of the Geological Society of Finland, 1989
The early Proterozoic Saari-Kiekki greenstone belt in Kuhmo, eastern Finland, is the deformed remnant of a NW‒SE-trending elongate structural basin c. 15 km long and up to 3 km wide.
E.J. Luukkonen
doaj   +1 more source

The Archaean to Proterozoic igneous rocks of the Pilbara region, Western Australia –internationally significant geology of a globally unique potential geopark

International Journal of Geoheritage and Parks, 2019
The Pilbara region of Western Australia, covering some 500 km × 500 km, provides a diversity of Archaean to Proterozoic igneous rocks in a relatively compact area that records a younging southward crustal history of igneous activity, sedimentation, early
V. Semeniuk, M. Brocx
doaj   +1 more source

A Reassessment of Petrochemistry of ~1.2 Ga Tonalitic Rocks of the Northern Tugela Terrane, Natal Metamorphic Belt, South Africa: Further Constraints on the Evolution of This Belt

Geological Journal, EarlyView.
Our petrochemical studies on ~1.2 Ga granitoids of the Natal Metamorphic Belt, South Africa, do not suggest any property similar to Phanerozoic‐style subduction‐related granitoids. Plot of Kotongweni Tonalite in Y versus Sr diagram (after Moyen 2011), note that most samples have Sr/Y < 50.
Palesa Leuta, Saumitra Misra, Thembiso O. Basupi   +2 more
wiley   +1 more source

Evidence that the GOE was a prolonged event with a peak around 1900 Ma

Geosystems and Geoenvironment, 2022
The great oxygenation event (GOE), the first of two major rises in atmospheric oxygen in Earth history, was initially placed near the Archean-Proterozoic boundary (∼2500 Ma).  More recently, the position of the GOE has been moved to between 2500 and 2300
Ross R. Large, Robert M. Hazen, Shaunna M. Morrison, Dan D Gregory, Jeffrey A. Steadman, Indrani Mukherjee   +5 more
doaj   +1 more source

Apatite in Carbonatite Preserving Primary Magmatic, Post‐Magmatic Overgrowth, and Post India‐Asia Collision‐Related Hydrothermal Alteration: Evidenced From U–Pb Isotope and Trace Element Geochemistry

Geological Journal, EarlyView.
U–Pb isotope and trace element geochemistry of apatite from carbonatites of Peshawar Plain Alkaline Igneous Province, western Himalaya shows Permo‐Carboniferous magmatism, an additional magmatic pulse during Cretaceous, and post‐magmatic hydrothermal/metasomatism during Oligocene. ABSTRACT U–Pb isotope and trace element geochemistry of apatite combined
Mehboob ur Rashid, Hafiz U. Rehman, Hao‐Yang Lee, Sun‐Lin Chung, Kaushik Das, Kazumasa Aoki, Muhammad Jawad Zeb, Nasir Ahmad, Muhammad Hussain, Hiroshi Yamamoto   +9 more
wiley   +1 more source

Geodynamics and Ore Content of Proterozoic Maphites in the Central Part of the Aldan-Stanovoy Shield (Southern North Asian Craton)

Геодинамика и тектонофизика
The study of diverse mantle-derived igneous complexes is important for interpreting geodynamic events, ore deposits formation mechanisms, and ore-forming fluid sources.
A. A. Kravchenko, A. V. Okrugin, V. I. Beryozkin, N. V. Popov, E. E. Loskutov   +4 more
doaj   +1 more source

Geology of Elu Inlet and Melville Sound, Nunavut, Arctic Canada

Journal of Maps, 2017
We present the results of helicopter- and field-based geological mapping of Elu Inlet and Melville Sound, Kitikmeot Region of Nunavut, Arctic Canada. The area includes a ∼150 km-wide belt of Proterozoic sedimentary rocks that unconformably overlie the ...
Alessandro Ielpi, Robert H. Rainbird, J. Wilder Greenman, C. Gabriel Creason   +3 more
doaj   +1 more source

Hot, Wide, Continental Back-arcs Explain Earth’s Enigmatic mid-Proterozoic Magmatic and Metamorphic Record

Tektonika, 2023
Higher than average thermobaric ratios (temperature/pressure) of metamorphic rocks and abundant ‘dry’ ferroan magmatism including massif anorthosite suites are two enigmatic features of the mid-Proterozoic (1.85–0.85 Ga) that have unclear origins.
Nick Roberts, Kent Condie, Richard Palin, Christopher Spencer   +3 more
doaj   +1 more source

Proterozoic basins of Canada: Early Proterozoic sequences in Labrador

, 1981
Early Proterozoic ( Aphebian) sedimentary and volcanic rocks in Labrador are described from two tectonic belts: the Churchill Province of western Labrador, and the Makkovik Subprovince of eastern Labrador. The Aphebian in the Churchill Province is represented mainly by the Labrador Trough ( Kaniapiskau Supergroup) but also in the Laporte Croup, Lake ...
R J Wardle, D G Bailey
openaire   +1 more source