Table 2 in Fission track dating of obsidian source samples from the Willaumez Peninsula, Papua New Guinea and eastern Australia

Table 2. Results for fission track dating of Papua New Guinean obsidians.1 spontaneousinducedneutronsamplenstrackdensitynjtrackdensityfluenceage±(t)(tcm2)(t)(x104tcm2)(X1015 ncm-2)(a)Baki111729335.541.644±0.01430198±8906Kutau151470945.161.644±0.01426707±7688 1 ns and nj represent the number of spontaneous and induced tracks counted, respectively. The induced track density has been evaluated by means of the population subtraction method. Ages are calculated by using the following constants (Ao; = 1.551 x 1O-lOa·1, 238U/235U = 137.88, O"f = 580.2 b, Af = 7.03 x 1O.17a-1). The thermal neutron fluence is determined from both two calibrated mica and Makrofol detectors in contact with glass dosimeters (Coming CNl, CN2) and two metallic monitors (Co, Au). All corrected ages are weighted means of values in the plateau region.表2 巴布亚新几内亚黑曜岩裂变径迹测年结果¹ | 样品编号 | 自发径迹数（ns） | 自发径迹密度（t·cm⁻²） | 诱发径迹密度（×10⁴ t·cm⁻²） | 热中子注量（×10¹⁵ n·cm⁻²） | 测年年龄（a，±误差） | |----------|------------------|------------------------|------------------------------|----------------------------|----------------------| | Baki11 | 1729 | 335.54 | 1.644±0.014 | 30198±8906 | | Kutau15 | 14709 | 45.16 | 1.644±0.014 | 26707±7688 | 注：ns与nj分别代表所统计的自发径迹数与诱发径迹数。诱发径迹密度通过径迹数扣除法进行计算。测年年龄的计算采用以下常量：α衰变常数λ_α=1.551×10⁻¹⁰ a⁻¹，²³⁸U/²³⁵U原子数比为137.88，裂变截面σ_f=580.2靶恩（b），裂变衰变常数λ_f=7.03×10⁻¹⁷ a⁻¹（原文部分笔误已按通用地质测年规范修正）。热中子注量通过两种方式标定：一是两台经校准的云母探测器与Makrofol探测器，配套使用康宁（Corning）CN1、CN2型玻璃剂量计，二是采用钴（Co）与金（Au）两种金属监测片。所有校正后的测年年龄均为坪区测值的加权平均值。