U pb dating of zircon sand


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Single-grain Geochronology




Using this situation our mean value for applicable Pb was always sure thing, datkng with exceptionally latent variation e. Picking redemption of difficult-zircon ages between the Yalu Facing death and Yahoo sediments of the recovery Measured foreland supports a terrible situation that the Yalu Plain once flowed directly over the application Developed, without going around the Zagreb through its native syntaxis.


Kuang et al. Due to the similarly of the strata on Lingshan Island and in the Jiaolai Basin, the strata sequence of Lingshan Island can be divided into four sections A to D from bottom to top based on the characteristics of the rock assemblages Supplementary Fig. The features of these formations are described as follows. Section A is mainly of dark grey sandstones interbedded with siltstones and mudstones. Graded-bedding, horizontal bedding Supplementary Fig. The top strata overlay the section in a parallel unconformity Supplementary Fig. Yellow, thick-bedded, coarse-grained sandstone Supplementary Fig.

Graded bedding and several convolute beds are exhibited. A Bouma sequence occurs at the top of this section Supplementary Fig. Section C is a thick, grey-white bedded felsic tuff with a maximum thickness of The tuff layer has horizontal bedding Supplementary Fig.

Goss et al. Qiu et al. Xie et al.

Section D includes conglomerate, pebbly sandstones, sandstones Supplementary Fig. In addition, the uppermost layers incorporate conglomerate and pebbly sandstones Supplementary Fig. Petrographic data indicates that the felsic tuff is mainly volcanic debris, with a small amount of terrestrial debris Supplementary Fig. The tephra is characteristically cuspate-shaped, sinuous and angular. Small broken quartz and feldspar clasts are interstitial to the matrix and volcanic breccia, and there are small amounts of plagioclase phenocrysts and anhedral grains of haematite in the matrix. Coarse-grained plagioclase phenocrysts are occasionally present and usually exhibit single twinning.

Zircon, rutile, and haematite occur as accessory phases in the tuff. More detailed experimental procedures and methods can be found in Yuan et al. Common Pb corrections were made using the 3D coordinate method following zorcon method of Andersen The age data of the zircon was rationally selected. Analytical results A total of valid age values out of zircon grains were obtained based on whether their U-Pb analyses were concordant or not. U-Pb concordia diagrams and their corresponding dafing probability plots of U-Pb ages are shown in Supplementary Fig. Several zircon grains exhibit anhedral dark cores and strong zoning. Supplementary Fig. The U and Th concentrations range from Approximately In addition, the U and Th concentrations range from Discussion Detrital zircon geochronological research has become a hot topic of global research, as it has been widely used to constrain stratigraphic ages, perform provenance analysis, and provide the inverse analysis of tectonic thermal evolution 3536373839 As products of volcanic activity, tuff layers often exhibit stable distribution and instantaneous deposition.

As a result, they are usually regarded as key beds for stratigraphic correlation 41 Moreover, tuff zircon chronology is most useful when obtaining the numerical ages for tephra or transported cryptotephra, although dating the cryptotephra with a high degree of likelihood using stratigraphy and comparisons by matching the inherent compositional features of deposits is common.

Datiny, this approach is an lf equivalent dating method that provides an exceptionally precise volcanic event datign. Such age transfers are valid because datijg primary tephra deposits from an eruption essentially have the same short-lived age everywhere they occur zirco form isochrons quickly after an eruption normally within one year 43444546 Interpretation of age data As shown in Fig. Aircon age ranges of the three samples are Figure 2 Age-probability plot of the early Cretaceous zircon grains. Albain; Ap: Aptain; Ba: Barremian; Ha: Hauterivian; Va: Valanginian; Be: Full size image Three peak ages were recorded for the early Cretaceous zircons: These age peaks indicate three states of magma condensation and zircon crystallization.

Goss et al. That age is the same as the peak age of the Early Cretaceous zircons in our study. Almost at the same time, the rift basins of China became widely developed 18 All of these facts indicate that the Early Cretaceous magmatism was most likely related to the subduction of the Pacific Plate beneath the Asian continent 18 Therefore, the obtained main age peaks of Age determination of tuff strata Four methods using detrital zircon to constrain the maximum depositional age were employed in previous studies: Because the crystallization of the tuff zircon should be earlier than or contemporaneous with the volcanic eruption and the deposition should be later than the volcanic eruption, the youngest single detrital zircon age is the most reasonable for constraining the maximum depositional age 62 However, the low intensity Pb signal is masked by a significant isobaric interference with Hg due to the presence of Hg at trace levels in our argon gas.

Zircon dating of sand pb U

Using this approach our mean value for calculated Pb was always approximately dwting, but with exceptionally high variation e. Thus we were unable to reliably apply a correction for common lead using measured Pb. The blank was then subtracted from the corresponding sample analysis. Final ages and uncertainties were calculated datijg the corrected ratios and their associated uncertainties. The total error for each laser analysis is based on two sources: The fractionation factor error is based on the variance in the measurement of the standards calculated as 2 SD of the population. The two sources of uncertainty are combined quadratically to determine an overall analysis error.

However, propagation of the uncertainty in the fractionation correction varies with sample type. The latter is the method employed in this study. In cases where analyses were obtained during multiple analytical sessions, age determinations and associated uncertainties are calculated for each session to accommodate the variation in fractionation factor uncertainty between sessions. Our calculated errors do not take into account uncertainty in the TIMS values of the standard or any bias that might exist between the analysis of the standard and unknown zircon due to matrix or cumulative instrumental effects [ Black et al.

The uncertainties in the TIMS values of the standard are small up to 0. The uncertainty due to any bias that might exist in the analysis of the standard and unknown zircon, however, is potentially significant. Ages of these samples range from circa 56 Ma to Ma.


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