Phase-space diagram of the NGC 3100 group. NGC 3100 is shown in red, while H I detections are shown in blue, and non-detections in grey. Triangles indicate group members from the Kourkchi & Tully (2017) catalogue that are located outside the field of view of ATCA. The dotted line shows the caustic curve defined by the escape velocity of the group. Interestingly, most H I detections are located within the virialised region of the group (dashed-dotted line). The proximity of NGC 3095 and DwN suggests a recent interaction with NGC 3100.