Insights into crust formation and recycling in North Africa from combined U–Pb, Lu–Hf and O isotope data of detrital zircons from Devonian sandstone of southern Libya

2013 ◽  
Vol 386 (1) ◽  
pp. 281-292 ◽  
Author(s):  
Guido Meinhold ◽  
Andrew C. Morton ◽  
C. Mark Fanning ◽  
James P. Howard ◽  
Richard J. Phillips ◽  
...  
Keyword(s):  
North Africa ◽  
Detrital Zircons ◽  
Crust Formation ◽  
Isotope Data ◽  
O Isotope

Detrital chromites reveal Slave craton’s missing komatiite

Geology ◽  
2021 ◽  
Author(s):  
Rasmus Haugaard ◽  
Pedro Waterton ◽  
Luke Ootes ◽  
D. Graham Pearson ◽  
Yan Luo ◽  
...  
Keyword(s):  
Narrow Range ◽  
Thermal Evolution ◽  
Group Element ◽  
Detrital Zircons ◽  
Isotopic Data ◽  
Crust Formation ◽  
Slave Craton ◽  
Provenance Studies ◽  
Juvenile Crust ◽  
Greenstone Belts

Komatiitic magmatism is a characteristic feature of Archean cratons, diagnostic of the addition of juvenile crust, and a clue to the thermal evolution of early Earth lithosphere. The Slave craton in northwest Canada contains >20 greenstone belts but no identified komatiite. The reason for this dearth of komatiite, when compared to other Archean cratons, remains enigmatic. The Central Slave Cover Group (ca. 2.85 Ga) includes fuchsitic quartzite with relict detrital chromite grains in heavy-mineral laminations. Major and platinum group element systematics indicate that the chromites were derived from Al-undepleted komatiitic dunites. The chromites have low 187Os/188Os ratios relative to chondrite with a narrow range of rhenium depletion ages at 3.19 ± 0.12 Ga. While these ages overlap a documented crust formation event, they identify an unrecognized addition of juvenile crust that is not preserved in the bedrock exposures or the zircon isotopic data. The documentation of komatiitic magmatism via detrital chromites indicates a region of thin lithospheric mantle at ca. 3.2 Ga, either within or at the edge of the protocratonic nucleus. This study demonstrates the applicability of detrital chromites in provenance studies, augmenting the record supplied by detrital zircons.

scholarly journals Potential influence of a planned landfill on a high karst plateau in Southwestern Montenegro to nearby karstic springs

2021 ◽  
Vol 50 (2-3) ◽  
Author(s):  
Micha Horacek ◽  
Milan Radulovic ◽  
Dejan Jancic ◽  
Stefan Wyhlidal ◽  
Golub Culafic
Keyword(s):  
Drinking Water ◽  
Water Supply ◽  
Water Samples ◽  
Catchment Area ◽  
Winter Precipitation ◽  
Potential Influence ◽  
Potential Threat ◽  
Isotope Data ◽  
O Isotope ◽  
Good Agreement

The potential threat of a landfill projected on a high karst plateau in southwest Montenegro is investigated with respect to the subjacent nearby springs. The locality is called Duboki do. As the springs are used for drinking water supply this investigation is urgently needed. For the springs exist two hypotheses concerning their catchment area: I) from the high karst plateau, or II) from a topographically lower area. The stable H- and O-isotope ratios of water samples from the springs are compared with precipitation isotope data, to reveal the catchment area of the springs. The isotope results indicate that the catchment area of the springs is at higher altitude fitting to, and in good agreement with, winter precipitation from the high karst plateau of the planned land-fill locality.

Source and magmatic evolution inferred from geochemical and Sr-O-isotope data on hybrid lavas of Arso, the last eruption at Ischia island (Italy; 1302 AD)

2017 ◽  
Vol 331 ◽  
pp. 1-15 ◽  
Author(s):  
Raffaella Silvia Iovine ◽  
Fabio Carmine Mazzeo ◽  
Ilenia Arienzo ◽  
Massimo D'Antonio ◽  
Gerhard Wörner ◽  
...  
Keyword(s):  
Magmatic Evolution ◽  
Isotope Data ◽  
Ischia Island ◽  
O Isotope

Removal of continental lithosphere beneath the Canary archipelago revealed from a U Pb Age and Hf/O isotope study of modern sand detrital zircons

Lithos ◽  
2020 ◽  
Vol 362-363 ◽  
pp. 105448
Author(s):  
Madisen Sagan ◽  
Larry M. Heaman ◽  
D. Graham Pearson ◽  
Yan Luo ◽  
Richard A. Stern
Keyword(s):  
Detrital Zircons ◽  
Continental Lithosphere ◽  
Isotope Study ◽  
O Isotope

scholarly journals What can we learn from N 2 O isotope data? – Analytics, processes and modelling

2020 ◽  
Vol 34 (20) ◽  
Author(s):  
Longfei Yu ◽  
Eliza Harris ◽  
Dominika Lewicka‐Szczebak ◽  
Matti Barthel ◽  
Margareta R.A. Blomberg ◽  
...  
Keyword(s):  
Data Analytics ◽  
Isotope Data ◽  
O Isotope

Stable isotope data of modern and ancient microbialites

2020 ◽  
Author(s):  
Alexandra S. Rodler ◽  
Sylvie Bruggmann ◽  
Steven Goderis ◽  
Philippe Claeys
Keyword(s):  
Environmental Conditions ◽  
Carbon And Oxygen Isotopes ◽  
Seawater Chemistry ◽  
Isotope Data ◽  
Diagenetic Alteration ◽  
First Results ◽  
O Isotope ◽  
Chemical Conditions ◽  
Geochemical Analyses ◽  
Redox Evolution

<p>Carbonate-based reconstructions of environmental conditions in the Precambrian rely heavily on shallow-water and typically microbially-mediated carbonates. This is because Precambrian carbonate rocks formed either microbially or abiotically. Consequently, organo-sedimentary carbonate structures (microbialites) are extensively used as archives of physico-chemical conditions of early Earth environments using traditional isotopes such as stable carbon and oxygen isotopes. When post-depositional alteration is carefully evaluated, valuable information on local seawater chemistry may be gained. More recently, non-traditional isotope systems are applied to microbialites for reconstructing, for example, the redox evolution of our planet. However, interpretations of non-traditional isotope data are challenging, and information on diagenetic alteration is crucial. We present geochemical analyses of modern and ancient microbialites, which are part of an ongoing study on the chromium isotope systematics in modern and fossil microbialites (1). Here, we focus on stable C- and O-isotope data and diagenetic alteration of the analysed microbialites. This approach aims to build a framework for interpreting paleo-environmental reconstructions using non-traditional isotope systems. First results of powdered sub-samples of the modern microbialites show that stable C- and O-isotope data reliably reflect the environmental conditions of their depositional setting: high δ<sup>13</sup>C values (+2 to +8 ‰) indicate extensive microbial activity and high δ<sup>18</sup>O values point to evaporative settings. One set of Precambrian microbialite samples also has high δ<sup>13</sup>C values (~+4 ‰), similar to the modern microbialites, but in comparison to modern samples, relatively low δ<sup>18</sup>O values (~-3 ‰). Yet, another set of Precambrian microbialite samples display both low δ<sup>13</sup>C (~-0.5 ‰) and δ<sup>18</sup>O values (-3 to -6 ‰). The results are interpreted to indicate a different depositional environment and/or more likely, a stronger degree of post-depositional diagenetic alteration that might also explain the comparatively low δ<sup>53</sup>Cr values of these samples.</p>

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