Differential zircon fertility of source terranes and natural bias in the detrital zircon record: Implications for sedimentary provenance analysis

Moecher, David P.; Samson, Scott D.

doi:10.1016/j.epsl.2006.04.035

Cited by 379 publications

(191 citation statements)

References 76 publications

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“…Zircon is known to be present in variable concentrations in different tectonographic terranes (discussed as 'zircon fertility' in Moecher and Samson 2006). Therefore a zircon-rich terrane would be overrepresented in any zircon geochronology study compared to a zirconsparse or zircon-poor terrane.…”

Section: Implications For Magmatism In Southern Gondwanamentioning

confidence: 99%

U-PB zircon tuff geochronology from the Karoo Basin, South Africa: implications of zircon recycling on stratigraphic age controls

McKay

Weislogel

Fildani³

et al. 2015

International Geology Review

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Along the >650 km long southern margin of the Karoo Basin in South Africa, we traversed four evenly spaced stratigraphic transects and collected 22 samples of volcanic, air-fall tuffs thought to be distal deposits derived from the Permian-Triassic Southern Gondwanan volcanic arc. We present 469 new U-Pb zircon ages determined by sensitive high-resolution ion microprobe reverse geometry (SHRIMP-RG) at the Stanford-USGS Microanalytical Center in order to constrain the maximum depositional ages for the southern Karoo Basin strata. Weighted means of these youngest coherent zircon populations were selected to maximize the number of analyses while minimizing the mean square weighted deviation (MSWD) to increase the robustness and decrease the influence of Pb-loss and inheritance in determining the maximum depositional age. Maximum depositional ages for the marine Ecca Group range from 250 to 274 Ma, whereas in the conformably overlying terrestrial Beaufort Group maximum depositional ages ranged from 257 to 452 Ma. Across the southern Karoo Basin, the Ecca Group tuffs produce maximum depositional ages that young upward; however, the Beaufort Group tuffs yield maximum depositional ages that are geochronologically out of sequence. Furthermore, maximum depositional ages of the Beaufort Group tuffs are consistently older than ash ages within the underlying marine strata. Our results are supported by previously published U-Pb tuff zircon geochronology in the Karoo Basin and demonstrate that the presence of out-of-sequence, older tuff ages are repeatable in Beaufort Group tuffs along the southern margin of the basin. We propose that tuffs in the Karoo Basin are correlative with tuffs in southern South America, and that the age spectra of these tuffs were influenced by magmatic crustal recycling. We use these data to highlight the complexity of U-Pb zircon datasets from tuffs, address the use of U-Pb zircon ages to provide absolute age controls, and discuss the implications of these new age controls on the Permian-Triassic Karoo strata.

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Section: Implications For Magmatism In Southern Gondwanamentioning

confidence: 99%

U-PB zircon tuff geochronology from the Karoo Basin, South Africa: implications of zircon recycling on stratigraphic age controls

McKay

Weislogel

Fildani³

et al. 2015

International Geology Review

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“…However, another possibility is that this Pb-loss event was more extensive, and the preponderance of younger grains isolated from the Ecca Group could be explained by a lower proportion of co-eruptive zircon (McKay et al, 2015) than in the overlying Beaufort Group . Zircon has been shown to be present in variable concentrations in different tectonostratigraphic terranes (Moecher and Samson, 2006). This variability also has the potential to create an age bias in the study of magmatic systems (McKay et al, 2015).…”

Section: Shrimp U-pb Geochronologymentioning

confidence: 99%

Refining the chronostratigraphy of the Karoo Basin, South Africa: magnetostratigraphic constraints support an early Permian age for the Ecca Group

Belica¹,

Tohver²,

Poyatos‐Moré

et al. 2017

Geophysical Journal International

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Summary:The Beaufort Group of the Karoo Basin, South Africa provides an important chrono-and biostratigraphic record of vertebrate turnovers that have been attributed to the End-Permian mass extinction events at ca. 252 Ma and ca. 260 Ma. However, an unresolved controversy exists over the age of the Beaufort Group due to a large dataset of published U-Pb SHRIMP zircon results that indicate a ca. 274-250 Ma age range for deposition of the underlying Ecca Group. This age range requires the application of a highly diachronous sedimentation model to the Karoo Basin stratigraphy and is not supported by published paleontologic and palynologic data. This study tested the strength of these U-Pb isotopic datasets using a magnetostratigraphic approach. Here we present a composite ~1500 m section through a large part of the Ecca Group from the Tanqua depocentre, located in the southwestern segment of the Karoo Basin. After the removal of two normal polarity overprints, a likely primary magnetic signal was isolated at temperatures above 450°C. This section is restricted to a reverse polarity, indicating that it formed during the Kiaman Reverse Superchron (ca. 318-265 Ma), a distinctive magnetostratigraphic marker for Early−Middle Permian rocks. The Ecca Group has a corresponding paleomagnetic pole at 40.8°S, 77.4°E (A95 = 5.5°). UPb SHRIMP ages on zircons are presented here for comparison with prior isotopic studies of the Ecca Group. A weighted mean U-Pb age of 269.5 ± 1.2 Ma was determined from a volcanic ash bed located in the uppermost Tierberg Formation sampled from the OR1 research core. The age is interpreted here as a minimum constraint due to a proposed Pb-loss event that has likely influenced a number of published results. A comparison with the Geomagnetic Polarity Time Scale as well as published U-Pb TIMS ages from the overlying Beaufort Group supports a ca. 290-265 Ma age for deposition of the Ecca Group.

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“…In recent years, sedimentary provenance technology has been improved by single grain radiometric dating of grain populations, for example detrital zircon U-Pb dating (Cawood and Nemchin, 2000;Fonneland et al, 2004;Morton et al, 2008;Beltrán-Triviño et al, 2013). Zircon as a kind of stable mineral can withstand the effects of weathering, erosion and thermal alteration (Cherniak and Watson, 2001;Košler and Sylvester, 2003), and possess a stable U-Pb isotopic system over a wide range of pressures, temperatures and fluid composition (Moecher and Samson, 2006;Zhao et al, 2013). The data of detrital zircon can provide more accurate and useful information of source areas, which makes it a powerful tool for basin provenance analysis that has been widely used all over the world in the last decade.…”

Section: Introductionmentioning

confidence: 99%

Provenance of Upper Miocene to Quaternary sediments in the Yinggehai-Song Hong Basin, South China Sea: Evidence from detrital zircon U–Pb ages

et al. 2014

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Differential zircon fertility of source terranes and natural bias in the detrital zircon record: Implications for sedimentary provenance analysis

Cited by 379 publications

References 76 publications

U-PB zircon tuff geochronology from the Karoo Basin, South Africa: implications of zircon recycling on stratigraphic age controls

U-PB zircon tuff geochronology from the Karoo Basin, South Africa: implications of zircon recycling on stratigraphic age controls

Refining the chronostratigraphy of the Karoo Basin, South Africa: magnetostratigraphic constraints support an early Permian age for the Ecca Group

Provenance of Upper Miocene to Quaternary sediments in the Yinggehai-Song Hong Basin, South China Sea: Evidence from detrital zircon U–Pb ages

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