ALBERT

Description: Marie Stopes was unquestionably one of the most remarkable women of the 20th century. The long-term significance of her work in pioneering the defence of women's rights, and in urging the general acceptance of contraception, far exceeds that of her contributions to palaeobotany. Nonetheless, between 1903 and 1935 she published a series of palaeobotanical papers that placed her among the leading half-dozen British palaeobotanists of her time. Her book Ancient Plants (1910; Blackie, London) was a successful pioneering attempt to popularize the subject for a non-botanical audience. Her contributions on the earliest angiosperms, on the formation of coal-balls, and, above all, on the nature and terminology of coal macerals have had a lasting impact on palaeobotanical thought. ... This 250-word extract was created in the absence of an abstract.

Description: This paper presents the results of an analogue modelling study on the reactivation of Riedel shears generated by basement-induced sinistral strike-slip faulting. It is based on a natural example in the Sierra de Albarracin, Iberian Range (Spain). The area has a polyphase deformation history, defined by the Variscan and Alpine orogenies. Late Variscan deformation was concentrated in a wide NW-SE shear zone with accompanying kilometre-scale E-W Riedel shears, which divided the Palaeozoic basement into large fault blocks. Alpine reactivation resulted in differential movements on the Riedel shears, as evidenced by a NW-SE chain of Palaeozoic inliers surrounded by a Mesozoic cover that generally shows minor deformations except near the E-W Riedel shears, where strata locally appear in near-vertical to overturned position. Sandbox analogue modelling was applied to improve insight into the structural history. It focused on the kinematics of spontaneously developed en echelon Riedel shears, reactivated in a rotated stress field. Sand with a controlled added strength was used to form Riedel shears in a first deformation phase to act as weak zones for a second phase. The modelling showed that in the first deformation phase large pop-up structures developed between the Riedel shears in a basement-induced sinistral strike-slip zone. Later reactivation in the N060{degrees}E and N135{degrees}E shortening directions was taken up respectively by sinistral-reverse and dextral-reverse shear along the pre-existing Riedel shears, but only if the sand on one side of the fault zone was allowed to move freely along the other. Scissor faulting along the Riedel shears with their complex 3D-geometry increased the height of the up-squeezed blocks. For experiments with fixed boundaries and no oil-water emulsion layer between the base plate and sand pack, thrusting at the backstop occurred rather than reactivation of the Riedel shears. This approach provided robust insights on the 4D development of the Sierra de Albarracin area.

Description: The Dumfries Basin aquifer supports groundwater abstraction for public supply, agriculture and industry. Abstraction is concentrated in the western part of the basin, where falling groundwater levels and deteriorating water quality both reflect the effects of intense pumping. There are two bedrock units: a predominantly breccia-coarse sandstone sequence in the west, interfingering with a predominantly sandstone sequence in the NE and east. The basin is bounded by weakly permeable Lower Palaeozoic rocks, and is largely concealed by variable superficial deposits. Surface water flows onto the basin from the surrounding catchment via the Nith and the Lochar Water and their respective tributaries. Direct rainfall recharge occurs via superficial sands and gravels, especially in the north, and discharge is predominantly to the rivers in the central area rather than the sea. A picture is developing of two main aquifer types within the basin: the high-transmissivity western sector underlain by a fracture-flow system with younger water and active recharge and a high nitrate content, compared with the east where groundwater residence times are longer and the storage capacity is higher.

Description: This paper examines progressive evolution of fault architectures through late orogenic compression- to post-orogenic extensional deformation in the Witwatersrand Basin, South Africa. The results indicate that rapid extrusion of mafic lavas of the lower Klipriviersberg Group formed a rigid lid' over the thrust front, changing its mechanical character and thereby driving a change of structural style from fold growth to passive roof duplex. Flexural tightening of folds in the core of the triangle zones at this time may have helped provide the dynamic permeability for distributed ingress of hydrothermal fluids and consequent gold mineralization. Shortly afterwards, the kinematic environment changed to become extensional. However, this study shows sharp lateral partitioning of the duration of kinematic style and structural amplification, such that thrusting and extension coexisted along strike in the upper Klipriviersberg Group. Thus the switch from thrusting to extension was progressive within the region, but locally very rapid. As the local kinematic environment became extensional, the fault system evolved progressively, with the early stages of kinematic changes being dominated by a process of reactivation by architectural scavenging, in which new extensional structures developed by selectively reusing and incorporating geometrical segments of earlier formed thrust and normal faults. Three basic stages can be identified in this evolution: broad extension above underlying detachments, involving reactivation of lateral structures; a period of intensive reactivation and kinematic reworking incorporating frontal structures; and an abandonment stage when the detailed influence of the earlier architecture diminished and the fault system developed larger through-going normal faults. The interaction of the newly developing fault system with the pre-existing architecture constitutes pre-programming of the final geometry, in which individual large faults are composed of a reticulated network of new and inherited segments. The observations are consistent with fault scale being a key control on the fault reactivation involved. This study has involved full integration of a dataset comprising 2D and 3D seismic reflection data, geological mine plans, logging of over 120 km of drill core and underground mapping in deep mine workings that pass 3 km into the seismic volume at 23 km depth.