Possible trace fossils of putative termite origin in the Lower Jurassic (Karoo Supergroup) of South Africa and Lesotho

Complex structures in the sandstones of the Lower Jurassic aeolian Clarens Formation (Karoo Supergroup) are found at numerous localities throughout southern Africa, and can be assigned to five distinct architectural groups: (1) up to 3.3-m high, free-standing, slab-shaped forms of bioturbated sandstones with elliptical bases, orientated buttresses and an interconnecting large burrow system; (2) up to 1.2-m high, free-standing, irregular forms of bioturbated sandstones with 2-cm to 4-cm thick, massive walls, empty chambers and vertical shafts; (3) about 0.15-m to 0.25-m high, mainly bulbous, multiple forms with thin walls (<2 cm), hollow chambers with internal pillars and bridges; (4) about 0.15-m to 0.2-m (maximum 1-m) high, free-standing forms of aggregated solitary spheres associated with massive horizontal, orientated capsules or tubes, and meniscate tubes; and (5) about 5 cmin diameter, ovoid forms with weak internal shelving in a close-fitting cavity. Based on size, wall thickness, orientation and the presence of internal chambers, these complex structures are tentatively interpreted as ichnofossils of an Early Jurassic social organism; the different architectures are reflective of the different behaviours of more than one species, the history of structural change in architectural forms (ontogenetic series) or an architectural adaptation to local palaeoclimatic variability. While exact modern equivalents are unknown, some of these ichnofossils are comparable to nests (or parts of nests) constructed by extant termites, and thus these Jurassic structures are very tentatively interpreted here as having been made by a soil-dwelling social organism, probably of termite origin. This southern African discovery, along with reported Triassic and Jurassic termite ichnofossils from North America, supports previous hypotheses that sociality in insects, particularity in termites, likely evolved prior to the Pangea breakup in the Early Mesozoic

A proof-of-concept Bitter-like HTS electromagnet fabricated from a silver-infiltrated (RE)BCO ceramic bulk

A novel concept for a compact high-field magnet coil is introduced. This is based on stacking slit annular discs cut from bulk rare-earth barium cuprate ((RE)BCO) ceramic in a Bitter-like architecture. Finite-element modelling shows that a small 20 turn stack (with a total coil volume of &lt;20 cm3) is capable of generating a central bore magnetic field of &gt;2 T at 77 K and &gt;20 T at 30 K. Unlike resistive Bitter magnets, the high-temperature superconducting (HTS) Bitter stack exhibits significant non-linear field behaviour during current ramping, caused by current filling proceeding from the inner radius outwards in each HTS layer. Practical proof-of-concept for this architecture was then demonstrated through fabricating an uninsulated four-turn prototype coil stack and operating this at 77 K. A maximum central field of 0.382 T was measured at 1.2 kA, with an accompanying 6.1 W of internal heat dissipation within the coil. Strong magnetic hysteresis behaviour was observed within the prototype coil, with ≈30% of the maximum central field still remaining trapped 45 min after the current had been removed. The coil was thermally stable during a 15 min hold at 1 kA, and survived thermal cycling to room temperature without noticeable deterioration in performance. A final test-to-destruction of the coil showed that the limiting weak point in the stack was growth-sector boundaries present in the original (RE)BCO bulk

The stratigraphic relationship between the Waterberg and Soutpansberg Groups in Northern Province, South Africa: Evidence from the Blouberg area

The relative stratigraphic position of the mid-Proterozoic Waterberg and Soutpansberg Groups in Northern Province has long been a subject of debate. These two major Proterozoic groups are juxtaposed in the Blouberg area, although the nature of the contact between the two sedimentary units is generally regarded as being faulted along the southern strand of the Melinda Fault. The Blouberg area is also the type locality for yet another small mid-Proterozoic succession, that of the Blouberg Formation, which locally outcrops beneath both the Waterberg and Soutpansberg strata. Existing maps of the Blouberg area show the Wyllie’s Poort Formation of the Soutpansberg Group to unconformably overlie rocks of the Blouberg Formation in the western foothills of Blouberg mountain. However, recent mapping suggests that these “Blouberg” strata themselves unconformably overlie the Blouberg Formation. This, therefore, raises important questions regarding the stratigraphic placement of these intermediate strata in the western foothills of Blouberg mountain, which outcrop unconformably above the Blouberg Formation and unconformably below the Wyllie’s Poort Formation. The intermediate strata are characterised by a thin basal conglomerate, consisting of cobbles of quartz, quartzite and B.I.F. This basal conglomerate grades vertically into trough cross-bedded sandstone and granulestone, which are characterised by heavy mineral concentrations on foresets. Although this facies compares poorly with strata of the Mogalakwena Formation in adjacent areas, which are generally more conglomeratic, they are identical with strata from more distal outcrops of the Mogalakwena Formation further to the south-west Palaeocurrent directions recorded from the intermediate strata are unimodal towards the west-south-west, in common with those recorded from the Mogalakwena Formation. This suggests that the intermediate strata, unconformably overlain by the Wyllie’s Poort Formation of the Soutpansberg Group, can be correlated with strata of the Mogalakwena Formation. The Waterberg Group thus appears to pre-date the Soutpansberg rocks. Additional evidence for the age relationships proposed here can be gained from an east-north-east-trending dyke swarm, which locally intrudes the basement, Blouberg and Waterberg rocks. This dyke swarm does not intrude Soutpansberg strata in adjacent areas. Patterns of spider diagrams of incompatible trace elements recorded from these dykes are very similar to those from the basaltic Sibasa Formation of the Soutpansberg Group. This suggests that the dyke swarm may have acted as feeders to the Sibasa lavas, and also suggests that the Soutpansberg Group post-dates the Waterberg Group