South Cornwall represents the westernmost part of the Variscan basement massif in SW England. Field-based investigations into the distribution, geometry, kinematics and relative chronology of post-Variscan deformation have been accompanied by preliminary palaeostress analyses. These indicate three episodes of basement reactivation: (1) Stephanian to Early Permian NNW–SSE extension, (2) Early to Late Permian strike-slip deformation, and (3) Late Permian to Triassic ENE–WSW extension. These data have been used to test and refine previously published models, based upon seismic and well data, of late Carboniferous to Triassic basement reactivation and sedimentary basin development within the Western Approaches Trough. We confirm that NNW–SSE regional extension and reactivation of ENE-striking Variscan thrusts had initiated by the latest Carboniferous, and that ENE–WSW regional extension and dip-slip reactivation of NNW-striking high-angle faults occurred during the Triassic. Permian strike-slip deformation recognized onshore may have contributed to the development of widespread unconformities within the oVshore basins.

Recent attempts to understand the origin of social fragmentation on the basis of spin models include terms accounting for two social phenomena: homophily—the tendency for people with similar opinions to establish positive relations—and social balance—the tendency for people to establish balanced triadic relations. Spins represent attribute vectors that encode G different opinions of individuals whose social interactions can be positive or negative. Here we present a co-evolutionary Hamiltonian model of societies where people minimise their individual social stresses. We show that societies always reach stationary, balanced, and fragmented states, if—in addition to homophily—individuals take into account a significant fraction, q, of their triadic relations. Above a critical value, $$q_c$$ q c , balanced and fragmented states exist for any number of opinions.

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The Rheic Ocean is a persistent feature of Paleozoic palaeogeographies whose closure contributed to the development of the Variscan orogen and formation of Pangaea. Geological and geophysical data indicate repeated episodes of Paleozoic rifting and plate convergence around SW England and the adjacent offshore areas. SW England occupied a lower plate position during the Devonian-Carboniferous, on the northern passive margin of the short-lived Rhenohercynian Ocean that had formed near a recently closed segment of the Rheic Ocean. Variscan plate convergence resulted in the development of the composite southwardsdipping Rheic-Rhenohercynian suture zone by the latest Devonian and inversion of the lower plate basins during the Carboniferous. Early Permian NNW-SSE extensional reactivation of this suture zone controlled the development of the Western Approaches Basins in its hangingwall and provides an excellent example of Wilson Cycle structural inheritance. The onshore expression of this episode includes shear zones and detachment faults consistent with top-to-the SSE extensional reactivation of Variscan thrust faults. There is a progression to higher-angle brittle extensional faults that cutout earlier structures. Exhumation of the lower plate was accompanied by Early Permian mantle and concomitant crustal partial melting, the construction of the Cornubian Batholith, and W-Sn-Cu fracture-hosted mineralisation.

Recent attempts to understand the origin of social fragmentation are based on spin models which include terms accounting for two social phenomena: homophily-the tendency for people with similar opinions to establish positive relations-and social balance-the tendency for people to establish balanced triadic relations. Spins represent attribute vectors that encode multiple (binary) opinions of individuals and social interactions between individuals can be positive or negative. Recent work suggests that large systems of N 1 individuals never reach a balanced state (where unbalanced triads with one or three hostile links remain), provided the number of attributes for each agent is less than O(N 2 ) [Phys. Rev. Lett. 125, 078302]. Here we show that this statement is overly restrictive. Within a Hamiltonian framework that minimizes individuals' social stress, we demonstrate that stationary, balanced, but fragmented states can be reached for any number of attributes, if, in addition to homophily, individuals take into account a significant fraction, q, of their triadic relations. Above a critical value qc, balanced states result. This result also holds for sparse realistic social networks. Finally, in the limit of small q, our result agrees with that of [Phys. Rev. Lett. 125, 078302].