Greenstone burial-exhumation cycles at the late Archean transition to plate tectonics.

Converging lines of evidence suggest that, during the late Archean, Earth completed its transition from a stagnant-lid to a plate tectonics regime, although how and when this transition occurred is debated. The geological record indicates that some form of subduction, a key component of plate tectonics-has operated since the Mesoarchean, even though the tectonic style and timescales of burial and exhumation cycles within ancient convergent margins are poorly constrained. Here, we present a Neoarchean pressure-temperature-time (P-T-t) path from supracrustal rocks of the transpressional Yilgarn orogen (Western Australia), which documents how sea-floor-altered rocks underwent deep burial then exhumation during shortening that was unrelated to the episode of burial.

Wedge tectonics in South China: constraints from new seismic data.

Collisional orogens form when tectonic forces amalgamte fragments of Earth's continental lithosphere. The sutures between individual fragments, or terranes, are potential sites of weakness that facilitate subsequent continental breakup. Therefore, the lithospheric architecture of collisional orogens provides key information for evaluating the long-term evolution of the continental interior: for example, the South China Block (SCB), where the tectonic history is severely obscured by extensive surface deformation, magmatism, and metamorphism.

No evidence for high-pressure melting of Earth's crust in the Archean.

Much of the present-day volume of Earth's continental crust had formed by the end of the Archean Eon, 2.5 billion years ago, through the conversion of basaltic (mafic) crust into sodic granite of tonalite, trondhjemite and granodiorite (TTG) composition. Distinctive chemical signatures in a small proportion of these rocks, the so-called high-pressure TTG, are interpreted to indicate partial melting of hydrated crust at pressures above 1.

Nonlinear analysis of natural folds using wavelet transforms and recurrence plots.

Three-dimensional models of natural geological fold systems established by photogrammetry are quantified in order to constrain the processes responsible for their formation. The folds are treated as nonlinear dynamical systems and the quantification is based on the two features that characterize such systems, namely their multifractal geometry and recurrence quantification. The multifractal spectrum is established using wavelet transforms and the wavelet transform modulus maxima method, the generalized fractal or Renyi dimensions and the Hurst exponents for longitudinal and orthogonal sections of the folds.