The principal objective of the Hominin Sites and Paleolakes Drilling project (HSPDP) is to study the relationship between climate and environmental change and the implications on human evolution in eastern Africa. For this purpose, HSPDP has recovered a 228 m core in the Chemeron Formation of the Baringo Basin (Kenya). The Chemeron Formation spans approximately 3.7 Myr, from around 1.6 to 5.3 Ma, and has yielded many vertebrate fossils, including fossil hominins. The magnetostratigraphy of the Baringo core contributes to the chronological framework. A total of 567 individual paleomagnetic samples were collected from 543 levels at regular intervals throughout the core and 264 were processed using thermal and alternative field stepwise demagnetizations. In most samples, distinct Low-Temperature (LT; 20–150 °C) and High-Temperature (HT; 150–550 °C) Characteristic Remanent Magnetization (ChRM) could be determined. Typical demagnetization behaviors and some rock magnetic experiments suggest titanomagnetite acts as the main carrier of the HT ChRM with pervasive secondary overprints in normal polarity expressed by the LT component. Normal and reversed polarities were identified based on the secondary overprints LT ChRM directions, either parallel or antiparallel to the HT ChRM directions respectively. Our study identified four paleomagnetic reversals interpreted as the Matuyama-Gauss, Gauss-Kaena, Kaena-Gauss and the Gauss-Mammoth transitions. These boundaries provide chronostratigraphic tie-points that can be combined with those derived from ⁴⁰Ar/³⁹Ar dating of tuffs (Deino et al., this issue) and together indicate that the HSPDP Baringo core has an age range of ~3.3 Ma to ~2.6 Ma. The consistent paleomagnetic and radioisotopic age constraints are incorporated into a Bayesian age model of the core (Deino et al., this issue).

Hominin Sites and Paleolakes Drilling项目（HSPDP）的主要目标是研究气候与环境变化之间的关系以及对东部非洲人类进化的影响。为此，HSPDP在巴林戈盆地（肯尼亚）的Chemeron组中采出了228 m的岩心。Chemeron组跨度约为3.7 Myr，从1.6 Ma到5.3 Ma，并产生了许多脊椎动物化石，包括人化石。Baringo岩心的地磁地层学有助于建立年代学框架。在整个岩心中以规则的时间间隔从543个水平收集了总共567个古磁样本，并使用热场和交替场逐步退磁法对264个进行了处理。在大多数样品中，明显的低温（LT; 20–150°C）和高温（HT; 150–550°C）可以确定特征剩磁（ChRM）。典型的退磁行为和一些岩石磁实验表明，钛磁铁矿充当HT ChRM的主要载体，并具有由LT组分表示的正常极性的普遍次级叠印。基于次级套印LT ChRM方向（分别平行于或反向平行于HT ChRM方向），确定了正向和反向极性。我们的研究确定了四个古磁逆转，分别解释为Matuyama-Gauss，Gauss-Kaena，Kaena-Gauss和Gauss-Mammoth转换。这些边界提供了年代地层联系点，可以与从 典型的退磁行为和一些岩石磁实验表明，钛磁铁矿充当HT ChRM的主要载体，并具有由LT组分表示的正常极性的普遍次级叠印。基于次级套印LT ChRM方向（分别平行于或反向平行于HT ChRM方向），确定了正向和反向极性。我们的研究确定了四个古磁逆转，分别解释为Matuyama-Gauss，Gauss-Kaena，Kaena-Gauss和Gauss-Mammoth转换。这些边界提供了年代地层联系点，可以与从 典型的退磁行为和一些岩石磁实验表明，钛磁铁矿充当HT ChRM的主要载体，并以LT组分表示的正常极性弥漫性二次覆盖。基于次级套印LT ChRM方向（分别平行于或反向平行于HT ChRM方向），确定了正向和反向极性。我们的研究确定了四个古磁逆转，分别解释为Matuyama-Gauss，Gauss-Kaena，Kaena-Gauss和Gauss-Mammoth转换。这些边界提供了年代地层联系点，可以与从 基于次级套印LT ChRM方向（分别平行于或反向平行于HT ChRM方向），确定了正向和反向极性。我们的研究确定了四个古磁逆转，分别解释为Matuyama-Gauss，Gauss-Kaena，Kaena-Gauss和Gauss-Mammoth转换。这些边界提供了年代地层联系点，可以与从 基于次级套印LT ChRM方向（分别平行于或反向平行于HT ChRM方向），确定了正向和反向极性。我们的研究确定了四个古磁逆转，分别解释为Matuyama-Gauss，Gauss-Kaena，Kaena-Gauss和Gauss-Mammoth转换。这些边界提供了年代地层联系点，可以与从凝灰岩的⁴⁰ Ar / ³⁹ Ar年代（Deino等，本期），一起表明HSPDP Baringo岩心的年龄范围为〜3.3 Ma至〜2.6 Ma。一致的古磁性和放射性同位素年龄约束被纳入核心的贝叶斯年龄模型（Deino等，本期）。