Data from the coupled detrital zircon U–Pb and Hf case study of the Sibumasu Terrane in northwest Thailand
Description
This dataset is the first coupled zircon U-Pb and Hf analysis from Ordovician to Triassic sediments of the Sibumasu Terrane in northwest Thailand. This dataset includes sample imagery, a cumulative kernel density estimate used to determine a consistent age cut off for the U-Pb isotopic systems of all eight samples and the relevant analytical data tables from LA–ICP–MS (U-Pb) and Multicollector (U-Pb and Lu-Hf) instruments. Information on each specific dataset are detailed below. Both the U–Pb and Hf datasets show older Proterozoic age peaks characteristic of Gondwana and the emergence of an Indosinian source in the younger units. Our data are consistent with other published studies from Sibumasu indicating a contiguous terrane, inconsistent with composite terrane reconstructions. These results and implications are explored further in the associated Journal of Asian Earth Sciences submission, which should be cited when using this dataset. Fig. 1: Thin sections, outcrop and hand specimens of samples. Minerals present are labelled where: Qtz is quartz; Ol is olivine; L is undifferentiated lithic fragments; Bt is biotite; Mu is muscovite; Am is amphibole mainly hornblende in these samples); Pl is plagioclase; Mc is microcline and Px is pyroxene. (a) Hand specimen of RDT15_078 (b) RDT16_001 thin section image in Cross Polarised Light (XPL), (c) Hand specimen of RDT15_066, (d) RDT16_018 overview thin section image in Cross Polarised Light (XPL), (e) RDT16_008 thin section image illustrating olivine (Ol) detritus in Plane Polarised Light (PPL) (f) RDT16_008 thin section image showing olivine (Ol) detritus in XPL, (g) RDT16_019 overview thin section image in XPL, (h) RDT16_006 field location, (i) RDT16_012 field locality (j) RDT16_012 overview thin section image in XPL. Fig. 2: General geological setting for sample RDT16_012 (side road west of Khun Yuam). A) Outcrop photograph of thinly bedded cherts and shales inferred to be of Middle Triassic age (Baum et al., 1981), i.e. Mae Sariang Formation. B) Outcrop photography of well-bedded sandstones and pebbly sandstones, with interbedded shales. C) Oblique Google Earth Image showing the geology west of Khun Yuam, around Ban Pratu Muang. D) Schematic cross-section showing main geological relationships along the side road east of Ban Pratu Muang. Fig. 3: Cumulative kernel density estimate (KDE) of all eight samples' age distributions from northwest Thailand. To determine the most appropriate and precise zircon U–Pb ages for this study’s dataset, the KDE of all ±10% discordant data was used to determine the minima of the data (206Pb/238U ages between 1350–1383 Ma). It was then decided that all 206Pb/238U ages ≤1351 Ma would be used for age determination, utilising the 207Pb/206Pb age for all older grains. Table 1: Main isotopes and ratios measured using LA–ICP–MS and Multicollector Table 2: LA–ICP–MS Analytical Method Information Table 3: Lu–Hf Standards and Analytical Parameters
Files
Steps to reproduce
To use this dataset, please also cite the relevant associated submission to the Journal of Asian Earth Sciences Special Issue by Dew et al. https://doi.org/10.1016/j.jseaes.2021.104709