Numerical modelling of inversion tectonics in fold-and-thrust belts

This work presents numerical experiments of inversion of rift basins and consequent sub-thrust imbrication in tectonic wedges. Half-graben basins initially develop and then are covered with a post-rift sequence bearing a décollement-prone horizon (i.e., the upper décollement). A total of twelve models of tectonic inversion have been conducted varying (i) the strength of inherited extensional fault arrays and (ii) applying different fluid pressure ratios (i.e., strength) within syn-rift strata. Combinations of those were simulated using different internal angles of friction for the inherited faults, different strengths for the syn-rift infill and for the upper décollement. Results show that changes in relative strength between inherited faults, syn-rift deposits and the upper crustal décollement leads to important variations in structural styles. Weak faults systematically favour the compressional reactivation of inherited extensional faults. Weak syn-rift sediments favour hanging wall by-pass structures instead of fault reactivation and less internal deformation of the syn-rift deposits. Weak upper décollements supports the accretion of basement in a hinterland antiformal stack, decoupling of basement and cover, and forward tectonic transport of rift basins. Strong upper crustal décollements favours basement and cover coupling, can lead to fault reactivation in the absence of weak faults and syn-rift sediments, however combinations of weak faults and strong upper décollement shows fault reactivation, weak syn-rift sediments and strong upper décollement form hanging wall by-pass structures. Modelling results are compared to natural case studies

A novel rpotein-mineral interface

Transferrins transport Fe3+ and other metal ions in mononuclear-binding sites. We present the first evidence that a member of the transferrin superfamily is able to recognize multi-nuclear oxo-metal clusters, small mineral fragments that are the most abundant forms of many metals in the environment. We show that the ferric ion-binding protein from Neisseria gonorrhoeae (nFbp)readily binds clusters of Fe3+, Ti4+, Zr4+ of Hf4+ in solution. The 1.7A resolution crystal structure of Hf-nFbp reveals three distinct types of clusters in an open, positively charged cleft between two hinged protein domains. A di-tyrosol cluster nucleation motif (Tyr195-Tyr196) is situated at the bottom of this cleft and binds either a trinuclear oxo-Hf cluster, which is capped by phosphate, or a pentanuclear cluster, which in turn can be capped with phosphate. This first high-reesolution structure of a protein-mineral interface suggests a novel metal-uptake mechanism and provides a model for protein-mediated mineralization/dissimilation, which plays a critical role in geochemical processes