scholarly journals Detrital zircon petrochronology of central Australia, and implications for the secular record of zircon trace element composition

Geosphere ◽  
2021 ◽  
Author(s):  
Charles Verdel ◽  
Matthew J. Campbell ◽  
Charlotte M. Allen
Keyword(s):  
Trace Element ◽  
Continental Crust ◽  
Detrital Zircon ◽  
Isotope Composition ◽  
Regional Scale ◽  
Large Data ◽  
Hf Isotope ◽  
Geological Time ◽  
Related Factors ◽  
Data Set

Hafnium (Hf) isotope composition of zircon has been integrated with U-Pb age to form a long-term (>4 b.y.) record of the evolution of the crust. In contrast, trace element compositions of zircon are most commonly utilized in local- or regional-scale petrological studies, and the most noteworthy applications of trace element studies of detrital zircon have been in “fingerprinting” potential source lithologies. The extent to which zircon trace element compositions varied globally over geological time scales (as, for example, zircon U-Pb age abundance, O isotope composition, and Hf isotope composition seem to have varied) has been little explored, and it is a topic that is well suited to the large data sets produced by detrital zircon studies. In this study we present new detrital zircon U-Pb ages and trace element compositions from a continent-scale basin system in Australia (the Centralian Superbasin) that bear directly on the Proterozoic history of Australia and which may be applicable to broader interpretations of plate-tectonic processes in other regions. U-Pb ages of detrital zircon in the Centralian Superbasin are dominated by populations of ca. 1800, 1600, 1200, and 600 Ma, and secular variations of zircon Hf isotope ratios are correlated with some trace element parameters between these major age populations. In particular, elevated εHf(i) (i.e., radiogenic “juvenile” Hf isotope composition) of detrital zircon in the Centralian Superbasin tends to correspond with relatively high values of Yb/U, Ce anomaly, and Lu/Nd (i.e., depletion of light rare earth elements). These correlations seem to be fundamentally governed by three related factors: elemental compatibility in the continental crust versus mantle, the thickness of continental crust, and the contributions of sediment to magmas. Similar trace element versus εHf(i) patterns among a global zircon data set suggest broad applicability. One particularly intriguing aspect of the global zircon data set is a late Neoproterozoic to Cambrian period during which both zircon εHf(i) and Yb/U reached minima, marking an era of anomalous zircon geochemistry that was related to significant contributions from old continental crust.

scholarly journals Zircon U-Pb age, trace element and Hf isotope composition of Sepon Au-Cu deposit, Laos: tectonic and metallogenic implications

China Geology ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 36-48 ◽  
Author(s):  
Xin-yu Wang ◽  
◽  
Dian-hua Cao ◽  
Zong-qi Wang ◽  
An-jian Wang ◽  
...  
Keyword(s):  
Trace Element ◽  
Isotope Composition ◽  
Hf Isotope

Helminth species diversity of mammals: parasite species richness is a host species attribute

Parasitology ◽  
2008 ◽  
Vol 135 (14) ◽  
pp. 1701-1705 ◽  
Author(s):  
F. BORDES ◽  
S. MORAND
Keyword(s):  
Species Richness ◽  
Host Species ◽  
Parasite Species ◽  
Regional Scale ◽  
Large Data ◽  
Helminth Species ◽  
Future Research ◽  
Data Set ◽  
Parasite Species Richness ◽  
Trade Offs

SUMMARYStudies investigating parasite diversity have shown substantial geographical variation in parasite species richness. Most of these studies have, however, adopted a local scale approach, which may have masked more general patterns. Recent studies have shown that ectoparasite species richness in mammals seems highly repeatable among populations of the same mammal host species at a regional scale. In light of these new studies we have reinvestigated the case of parasitic helminths by using a large data set of parasites from mammal populations in 3 continents. We collected homogeneous data and demonstrated that helminth species richness is highly repeatable in mammals at a regional scale. Our results highlight the strong influence of host identity in parasite species richness and call for future research linking helminth species found in a given host to its ecology, immune defences and potential energetic trade-offs.

scholarly journals On the petrogenesis of Paleoarchean continental crust: U-Pb-Hf isotope and major-trace element constraints from the Bastar Craton, India

2021 ◽  
pp. 120337
Author(s):  
Alessandro Maltese ◽  
Klaus Mezger ◽  
Dewashish Upadhyay ◽  
Jasper Berndt ◽  
Erik E. Scherer
Keyword(s):  
Trace Element ◽  
Continental Crust ◽  
Hf Isotope ◽  
Bastar Craton

scholarly journals Early Earth zircons formed in residual granitic melts produced by tonalite differentiation

Geology ◽  
2021 ◽  
Author(s):  
Oscar Laurent ◽  
Jean-François Moyen ◽  
Jörn-Frederik Wotzlaw ◽  
Jana Björnsen ◽  
Olivier Bachmann
Keyword(s):  
Trace Element ◽  
Detrital Zircon ◽  
Early Earth ◽  
Forming Process ◽  
Data Set ◽  
Geological Materials ◽  
Zircon Crystallization ◽  
Trace Element Contents ◽  
Trace Element Signature ◽  
Chemical Trends

The oldest geological materials on Earth are Hadean (>4 Ga) detrital zircon grains. Their chemistry and apparently low Ti-in-zircon temperatures (≤700 °C) are considered to be inconsistent with crystallization in a magma of the tonalite-trondhjemite-granodiorite (TTG) suite, although these are the dominant Archean (4.0–2.5 Ga) silicic rocks. Using a new data set of trace element contents in zircons from Paleoarchean Barberton TTGs (South Africa) and thermodynamic modeling, we show that these zircons have crystallized at near-solidus conditions from a compositionally uniform granitic melt. This melt is residual from the crystallization of a less evolved (tonalitic) parent and thereby shows major and trace element compositions different from bulk TTG rocks. A global compilation reveals that most Hadean detrital and Archean TTG-hosted grains share a peculiar zircon trace element signature that is distinct from the chemical trends defined by Phanerozoic zircons. Our model shows that the low Ti contents of early Earth zircons reflect crystallization at higher temperatures (720–800 °C) than initially inferred due to lower modeled TiO2 activity in the melt relative to previous estimates. We therefore propose that near-solidus zircon crystallization from a chemically evolved melt in a TTG-like magmatic environment was the dominant zircon-forming process on the early Earth.

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