Alluvial and colluvial “cut and fill” deposits preserved in valleys of the Karoo, South Africa, reflect basin-scale adjustments in fluvial process-regime. Such deposits in the Wilgerbosch catchment have previously proven difficult to date using radiocarbon (¹⁴C) and optically stimulated luminescence (OSL) methods. In this paper, we test the suitability of K-feldspar post-IR infrared (pIRIR) methods on 19 samples from Africanders Kloof, a low-order tributary of the Sundays River. Using three carefully screened quartz OSL ages, radiocarbon dating and site stratigraphic considerations we argue that the pIRIR₁₇₀ protocol can be used to produce reliable age estimates. Fading rates for the pIRIR₁₇₀ signal are consistently low (average g_2days: 0.81 ± 0.58). The pIRIR₁₇₀ residuals are dose dependent (r² = 0.58); but are consistently low as a proportion (e.g. 1–4%) of sample equivalent dose (D_e). Despite the water-lain depositional context, single aliquot D_e distributions tend toward normality (for 11/19 samples) irrespective of aliquot size (2 mm or micro-aliquots containing 2–30 grains) with only a few statistical outliers per sample (max. n = 3) and overdispersion (OD) ranging from 1.6 to 30% excluding the two youngest (late Holocene) samples (OD: 37–87%). The resulting pIRIR₁₇₀ ages are in the correct stratigraphic order and illustrate the potential of pIRIR₁₇₀ luminescence dating to investigate the timing, processes and drivers of fluvial system adjustments across the Karoo.

保留在南非卡鲁山谷中的冲积和冲积“挖填”矿床，反映了河流流域的盆地规模调整。以前已证明，使用放射性碳（¹⁴ C）和光学激发发光（OSL）方法很难在Wilgerbosch集水区中找到此类沉积物。在本文中，我们对19种非洲样品Kloof（星期日河的低级支流）的19个样品进行了K长石后红外（pIRIR）方法的适用性测试。使用三个经过仔细筛选的石英OSL年龄，放射性碳测年和现场地层因素，我们认为pIRIR ₁₇₀协议可用于产生可靠的年龄估计。衰落率的pIRIR ₁₇₀信号一直较低（平均克_2天：0.81±0.58）。pIRIR ₁₇₀残留量与剂量有关（r ²  = 0.58）；但始终以样品当量剂量（D _e）的比例（例如1-4％）较低。尽管存在水滞沉积环境，但单个等分试样D _e分布趋于正态分布（对于11/19样品），而与等分试样的大小（2 mm或包含2–30颗粒的微等分试样）无关，每个样品只有几个统计异常值（最大值） 。n = 3），超分散（OD）范围为1.6％至30％，其中不包括两个最年轻的（晚全新世）样品（OD：37-87％）。所得的pIRIR ₁₇₀年龄处于正确的地层顺序，并说明了pIRIR ₁₇₀的潜力 发光测年法研究整个Karoo河流系统调整的时机，过程和驱动因素。