Many geological contexts lack suitable material for commonly applied absolute dating methods. Even if some regions contain potentially datable materials, they may be inappropriate for dating by existing geochronological techniques. Paleoanthropological localities on the Homa Peninsula, southwestern Kenya, have yielded important paleoanthropological material. These localities are, however, poorly constrained in time, and few radioisotopic ages have been published, because sediments derived from the Homa Mountain carbonatite complex commonly do not contain zircons for UPb dating or feldspars for ⁴⁰Ar/³⁹Ar dating. Additionally, apatite grains that are present have failed to produce precise isotope dilution-thermal ionization mass spectrometer (ID-TIMS) results due to their high common lead content. Apatite (UTh)/He dating using single-crystal laser fusion He determinations and the UTh isotope dilution method was applied to three formations with well-constrained ages to test the suitability of this technique for dating sediments on the peninsula. Two of the three Kanam Formation samples provide dates close to the approximately 6 million year age (Ma) provided by ⁴⁰Ar/³⁹Ar dates. The Abundu Formation was dated to 2.39 ± 0.29 Ma overlapping with the age of the Rawi Formation (C2An.1n Subchron, 3.05–2.59 Ma) to which it has been correlated. The age for the Kanjera South Member 1.54 ± 0.85 Ma overlaps with the expected 2 Ma age, though it has a large uncertainty. The apatite raw (UTh)/He ages are somewhat younger than the expected dates, but the technique shows promise.

许多地质背景缺乏适合常用绝对测年方法的材料。即使某些地区包含潜在的数据资料，它们也可能不适合通过现有的地质年代学技术确定年代。肯尼亚西南部霍马半岛的古人类学地点已经产生了重要的古人类学材料。然而，这些地点在时间上的限制很差，几乎没有发表过放射性同位素年龄，因为源自霍马山碳酸盐岩复合体的沉积物通常不含用于 U Pb 定年的锆石或用于⁴⁰ Ar/ ^{39 的}长石约会。此外，由于磷灰石颗粒的常见铅含量较高，因此无法产生精确的同位素稀释热电离质谱仪 (ID-TIMS) 结果。磷灰石 (U Th)/He 测年使用单晶激光融合 He 测定和 U Th 同位素稀释法应用于年龄限制良好的三个地层，以测试该技术对半岛沉积物测年的适用性。三个 Kanam 地层样品中的两个提供的日期接近⁴⁰ Ar/ ³⁹提供的大约 600 万年年龄 (Ma)日期。Abundu 组的年代为 2.39 ± 0.29 Ma，与其相关的 Rawi 组（C2An.1n Subchron，3.05-2.59 Ma）的年龄重叠。Kanjera 南段 1.54 ± 0.85 Ma 的年龄与预期的 2 Ma 年龄重叠，但具有很大的不确定性。磷灰石原料 (U Th)/He 的年龄比预期的日期要年轻一些，但该技术显示出前景。