Results 91 to 100 of about 24,344 (266)

Shocked zircons in the Onaping Formation: Further proof of impact origin [PDF]

The Onaping Formation fills the structural basin at Sudbury, Ontario, Canada. This formation is composed of three members: a basal, coarse, mainly quartzitic breccia (Basal Member); a light-colored, heavily included, polymict middle unit (Gray Member ...
Betterton, W. J., Bohor, B. F.
core   +1 more source

Confirmation of the impact origin of the Late Ordovician Tvären impact structure (southeast Sweden) and emplacement of impactites in a marine setting

Meteoritics &Planetary Science, EarlyView.
Abstract The Tvären structure in southeastern Sweden has been listed as a confirmed marine‐target impact structure for decades. However, to date, no measurements and/or indexed data of planar deformation features in quartz grains from the structure have been published or any other unequivocal evidence of impact.
Katarzyna J. Gajewska, Sanna Alwmark, Mikael Calner, Sylvain Richoz, Jens Ormö, Erik Sturkell, Carl Alwmark   +6 more
wiley   +1 more source

Polymict melt‐bearing breccia dikes in the Morokweng impact structure formed by slip‐induced mechanical mixing of pseudotachylite and cataclasite along large‐displacement impact faults

Meteoritics &Planetary Science, EarlyView.
Abstract A core drilled through shocked and faulted Archean granitoid gneisses and dolerites in the eroded peak ring of the 70–80 km diameter Morokweng impact structure intersects multiple centimeter‐ to meter‐wide clastic‐matrix breccias containing a polymict clast population of lithic and mineral clasts and altered, millimeter‐ to centimeter ‐size ...
Roger L. Gibson, S'lindile S. Wela, Leonidas C. Vonopartis, Marco A. G. Andreoli   +3 more
wiley   +1 more source

Confirming the impact origin of the São Miguel do Tapuio structure, northeastern Brazil

Meteoritics &Planetary Science, EarlyView.
Abstract The São Miguel do Tapuio structure (SMT) is a remarkable, nearcircular feature of about 21 km diameter, centered at 5°37.6′ S, 41°23.3′ W in Piauí state, northeastern Brazil. The structure is located within the sedimentary strata of the Paleozoic–Mesozoic Parnaíba Basin and predominantly comprises sandstones of the Devonian Pimenteiras and ...
Alvaro Penteado Crósta, Neivaldo Araújo de Castro, Marcos Alberto Rodrigues Vasconcelos, Airton Natanael Coelho Dias, Ludovic Ferrière, Wolf Uwe Reimold, Ana Maria Góes, Jackson Alves Martins, Liliana Sayuri Osako, Raimundo Mariano Gomes Castelo Branco   +9 more
wiley   +1 more source

U–Th isotopic microanalysis of zircon reference materials and KBSI working standards

Journal of Analytical Science and Technology, 2018
Background The 238U–230Th disequilibrium dating of the mineral zircon (ZrSiO4) provides an efficient tool for investigating the time scales of Quaternary magmatic processes.
Youn-Joong Jeong, Shinae Lee, Sook Ju Kim, Hui Je Jo, Keewook Yi, Albert Chang-sik Cheong   +5 more
doaj   +1 more source

Topographic Development History of the Alaska Range [PDF]

, 2013
he overall goal of this project is to use variations in sediment source through time as a proxy for deciphering the uplift history of the Alaska Range (Fig. 1).
Davis, Kailyn
core  

Natural Resources and Political Patronage in Africa: An Ethnicity Level Analysis

Review of Development Economics, EarlyView.
ABSTRACT We investigate the effect of resource discoveries on ethnicity‐level political patronage in Africa using a large geospatial dataset of 254 ethnic groups in 15 countries over the period 1960–2004. We find that the first (or single first) resource discovery in a virgin ethnic homeland increases the share of cabinet posts of that ethnicity.
Sambit Bhattacharyya, Nemera Mamo
wiley   +1 more source

Cenozoic magmatism petrogenesis and evolution in the Sangan mining district: using zircon mineral chemistry [PDF]

پترولوژی
Zircon is a significant mineral due to its ubiquitous occurrence, chemically resistant and refractory, that can survive both weathering and transport processes as well as high-temperature metamorphism and anatexis (Ballard et al., 2002).
Majid Ghasemi Siani, Behzad Mehrabi, Franz Neubauer   +2 more
doaj   +1 more source

Microbially generated ferruginous crusts: A potential biosignature of continental input in coastal settings

Sedimentology, EarlyView.
ABSTRACT Thin ferruginous sandy crusts are common on top of sandstone beds in the Early Permian post‐glacial deposits of the Paraná Basin in southern Brazil. These crusts usually preserve wrinkle structures, suggesting that they might be a product of microbial mediation.
Patrícia Weschenfelder, Renata Guimarães Netto, Alisson Klayton Martins   +2 more
wiley   +1 more source

U-Pb Geochronology and Trace Element Compositions of Zircon in Biotite Granite from the Bagaladong Pb-Zn Deposit, Tibet and Their Geological Significance

Yankuang ceshi, 2016
The Bagaladong Pb-Zn deposit is located in the eastern segment of the Gangdese back-arc uplift belt and lacks enough study with no available ages for ores and rocks.
WANG Li-qiang, XIE Fu-wei, WANG Yong
doaj   +1 more source