Data from the coupled detrital zircon U–Pb and Hf case study of the Sibumasu Terrane in northwest Thailand

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

本数据集为泰国西北部西马苏地体（Sibumasu Terrane）奥陶纪至三叠纪沉积岩中首次开展的锆石U-Pb与Hf同位素耦合分析数据集。本数据集包含样品成像数据、用于确定全部8个样品U-Pb同位素体系统一年龄截断值的累计核密度估计结果，以及来自激光剥蚀电感耦合等离子体质谱（LA–ICP–MS，用于U-Pb分析）和多接收质谱（用于U-Pb与Lu-Hf分析）的相关分析数据表。各细分数据集的详细信息如下文所述。

U-Pb与Hf同位素数据集均显示出冈瓦纳（Gondwana）典型的古元古代年龄峰值，且在年轻地层单元中出现了印支期（Indosinian）物源的信号。本数据集数据与西马苏地体其他已发表研究结果一致，支持该地块为连续地体的结论，与复合地体重建模型相悖。本研究的相关成果与认识已投稿至《亚洲地球科学杂志》（Journal of Asian Earth Sciences），使用本数据集时请引用该论文。

图1 样品的薄片、露头与手标本。图中标注的矿物缩写对应如下：Qtz为石英（quartz）；Ol为橄榄石（olivine）；L为未分化岩屑；Bt为黑云母（biotite）；Mu为白云母（muscovite）；Am为角闪石（amphibole，本样品中以普通角闪石为主）；Pl为斜长石（plagioclase）；Mc为微斜长石（microcline）；Px为辉石（pyroxene）。(a) RDT15_078手标本；(b) 正交偏光（Cross Polarised Light, XPL）下的RDT16_001薄片图像；(c) RDT15_066手标本；(d) 正交偏光下的RDT16_018薄片全景图像；(e) 单偏光（Plane Polarised Light, PPL）下显示橄榄石（Ol）碎屑的RDT16_008薄片图像；(f) 正交偏光下显示橄榄石（Ol）碎屑的RDT16_008薄片图像；(g) 正交偏光下的RDT16_019薄片全景图像；(h) RDT16_006野外采样点；(i) RDT16_012野外采样点；(j) 正交偏光下的RDT16_012薄片全景图像。

图2 样品RDT16_012的区域地质背景（位于坤央（Khun Yuam）西侧支路）。(A) 被推断为中三叠世的薄层状燧石与页岩露头照片（Baum等，1981），即湄沙良组（Mae Sariang Formation）；(B) 发育层理良好的砂岩、含砾砂岩夹页岩的露头照片；(C) 坤央西侧班普拉图孟（Ban Pratu Muang）周边区域的倾斜谷歌地球（Google Earth）地质影像；(D) 班普拉图孟东侧支路沿线主要地质关系示意剖面图。

图3 泰国西北部全部8个样品年龄分布的累计核密度估计（KDE）结果。为确定本数据集锆石U-Pb年龄的最优精确年龄，本研究对所有偏差率±10%的不协调数据的KDE曲线进行分析，以确定数据的最小值区间（206Pb/238U年龄介于1350~1383 Ma）。最终确定采用所有≤1351 Ma的206Pb/238U年龄进行年龄标定，对于年龄更大的锆石颗粒则采用207Pb/206Pb年龄。

表1 激光剥蚀电感耦合等离子体质谱（LA–ICP–MS）与多接收质谱测试的主要同位素及比值；表2 LA–ICP–MS分析方法参数；表3 Lu-Hf标样与分析参数。