Results 51 to 60 of about 34,869 (280)

Araguainha Dome, Brazil: A polygonal impact structure due to a complex pre‐impact regional structural framework

open access: yesMeteoritics &Planetary Science, EarlyView.
Abstract We investigated the structural framework of the north–northwestern Paraná Basin in Brazil to test whether the pre‐impact structures in this region may have had any influence on the first‐order formation and morphostructure of the Araguainha impact structure (AIS).
Renato B. Bernardes   +5 more
wiley   +1 more source

THE NEOPROTEROZOIC ISLAND-ARC ASSOCIATION OF THE MUKODEK GOLD-ORE FIELD, NORTHERN BAIKAL AREA

open access: yesГеодинамика и тектонофизика, 2015
Metamorphosed volcanic rocks of the Ushmukan suite were studied in the Mukodek gold-ore field located in the Baikal-Muya belt in the Northern Baikal area, Russia. The Ushmukan suite shows interleaving of ortoschists which compositions are widely variable.
V. A. Vanin   +2 more
doaj   +1 more source

Revisiting the Hummeln structure, Sweden—A shallow marine Cambrian impact structure

open access: yesMeteoritics &Planetary Science, EarlyView.
Abstract Hummeln is a simple impact structure located in south‐eastern Sweden. It is approximately 1.2 km in diameter and almost completely covered by a lake. Here, we present the first detailed investigation of impactites and mapping of the 164.25 m deep drill core Hummeln‐1 with a focus on impact metamorphism and the impact process.
S. Alwmark   +8 more
wiley   +1 more source

Zircon SHRIMP U-Pb Dating and Significance From Weathered Residual Kaolin Deposits on the Northern Margin of the Qinzhou-Hangzhou Suture Zone, China

open access: yesFrontiers in Earth Science, 2022
Weathered residual Kaolin deposits on the northern margin of the Qinzhou-Hangzhou Suture Zone are characterized by more feldspar-containing minerals and fewer dark minerals.
Chunhai Li   +8 more
doaj   +1 more source

Photosynthetic primary production in the Mesoproterozoic

open access: yesNew Phytologist, EarlyView.
Summary The Mesoproterozoic atmosphere had more CO2 and less O2 than at present. While the upper ocean was oxygenated, the deeper ocean was euxinic or ferruginous. Primary production was performed by Chlorobia, Cyanobacteria, Proteobacteria, and Archaeplastida.
Patricia Sánchez‐Baracaldo   +1 more
wiley   +1 more source

The Enigma of Neoproterozoic Giant Ooids—Fingerprints of Extreme Climate?

open access: yesGeophysical Research Letters, 2020
Geologists have documented at least 14 occurrences of “giant ooids,” a geologically rare type of carbonate allochem, in Neoproterozoic successions at low paleolatitudes.
Elizabeth J. Trower
doaj   +1 more source

Geochronology and Lu-Hf isotope of mafic-intermediate rocks from SW Salmas: implication for Neoproterozoic juvenile melts [PDF]

open access: yesپترولوژی, 2018
The southwest Salmas metamorphosed mafic-intermediate intrusive rocks are located in Sanandaj-Sirjan zone in NW of Iran. The metamorphosed intrusives rocks comprise metagabbro and metadiorite that intruded the Precambrian metamorphosed volcanic ...
Fahime kozekoulani   +2 more
doaj   +1 more source

Tellurium, selenium and cobalt enrichment in Neoproterozoic black shales, Gwna Group, UK : Deep marine trace element enrichment during the Second Great Oxygenation Event [PDF]

open access: yes, 2018
We are grateful to John Still for his skilled technical support and the ACEMAC facility at the University of Aberdeen. Research funded by NERC grant NE/M010953/1 and NERC facility grant IP-1631-0516. AJB is funded by NERC support of the Isotope Community
Armstrong, Joseph   +5 more
core   +2 more sources

Disentangling palaeoecological and outcrop controls on MISS occurrence in c. 1 Ga fluvio‐lacustrine facies of the Diabaig Formation, Scotland

open access: yesSedimentology, EarlyView.
ABSTRACT The c. 1 Ga Diabaig Formation of north‐west Scotland preserves diverse lacustrine and fluvial facies and abundant microbial and non‐microbial surficial sedimentary features. 172.6 m of section was logged across seven localities to assess the distribution of microbially induced sedimentary structures (MISS) relative to lithofacies, substrate ...
Seán T. Herron   +2 more
wiley   +1 more source

Zircon U-Pb dating of the Dizhuanggou Formation, Changjiaoba Group in the South Qinling Belt and its tectonic significance

open access: yesDizhi lixue xuebao
Objective  The Changjiaoba Group, located in the Foping area of the South Qinling Belt, is one of the few poorly-studied strata in the belt. The lack of an accurate composition and formation age of these strata has restricted research on the tectonic ...
LIU Zhihui   +4 more
doaj   +1 more source

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