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Strain localization is central to the transition between continental rifting and seafloor spreading. In the East African Rift System (EARS), there is an emerging understanding of the link between extensional pulses and magmatic episodes. We investigate modern magmatism located within the Turkana Depression and its relationship with the distribution of extensional strain. We probe the source of magmatism at South Island volcano using bulk rock, melt inclusion and olivine geochemical data and find that the magmas are derived from sub-lithospheric sources equivalent to magmatism in the more mature sectors of the rift. The depth extent of the magmatic plumbing system of South Island is constrained using vapour saturation pressures derived from bubble-corrected H 2 O and CO 2 concentrations in melt inclusions and the results indicate a magmatic system resembling modern axial volcanic systems observed in other parts of the EARS. The zone of focused axial magmatism that South Island represents has evolved contemporaneously with a region of focused axial faulting that has accommodated the majority of regional Holocene extension and subsidence at this latitude. We conclude that at South Island there has been a migration of magmatic and tectonic strain towards the modern zone of focused intrusion along this portion of the EARS. Supplementary material: S1–S2 image files, data table files S3–S6 and caption file S7 are available at https://doi.org/10.6084/m9.figshare.c.6026627 

Abstract The initial interaction between material rising from the African Large Low Shear Velocity Province and the African lithosphere manifests as the Eocene continental large igneous province (LIP), centered on southern Ethiopia and northern Kenya. Here we present a geographically well-distributed geochemical dataset comprising the flood basalt lavas of the Eocene continental LIP to refine the regional volcano-stratigraphy into three distinct magmatic units: (1) the highly-alkaline small-volume Akobo Basalts (49.4–46.6 Ma), representing the initial phase of flood basalt volcanism derived from the melting of lithospheric-mantle metasomes, (2) the primitive and spatially restricted Amaro Basalts (45.2–39.58 Ma) representing the early main phase of flood basalt volcanism derived from the melting of the upwelling thermochemical anomaly, and (3) the spatially extensive Gamo-Makonnen magmatic unit (38-28 Ma) representing the mature main phase of flood basalt volcanism that has undergone significant processing within the lithosphere resulting in relatively homogeneous compositions. The focused intrusion of these main phase magmas over 10 m.y. preconditioned the African lithosphere for the localization of strain during subsequent episodes of lithospheric stretching. The focusing of strain into the region occupied by this continental LIP may have contributed to the initial extension in SW Ethiopia associated with the East African Rift. Supplementary material at https://doi.org/10.6084/m9.figshare.c.5557626 

We have created an open‐source 3D printable microscope automatic stage and integrated camera system capable of providing a means for imaging microscope slides—the PiAutoStage. The PiAutoStage was developed to interface with the high‐quality optics of existing microscopes by creating an adaptable system that can be used in conjunction with a range of microscope configurations. The PiAutoStage automatically captures the entire area of a microscope slide in a series of overlapping high‐resolution images, which can then be stitched into a single panoramic image. We have demonstrated the utility of the PiAutoStage when attached to a transmitted light microscope by creating high‐fidelity image stacks of rock specimens in plane polarized and cross‐polarized light. We have shown that the PiAutoStage is compatible with microscopes that do not currently have a camera attachment by using two different optical trains within the same microscope: one set of imagery collected through the photography tube of a trinocular microscope, and a second set through a camera mounted to an ocular. We furthermore establish the broad adaptability of the PiAutoStage system by attaching it to a reflected light stereo dissection microscope to capture images of microfossils. We discuss strategies for the online delivery of these large‐sized images in a data efficient manner through the application of tiled imagery and open‐source Java‐based web viewers. The low cost of the PiAutoStage system, combined with the data‐efficient mechanisms of online delivery make this system an important tool in promoting the universal accessibility of high‐resolution microscope imagery.