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The composition of continental crust records the balance between construction by tectonics and destruction by physical and chemical erosion. Quantitative constraints on how igneous addition and chemical weathering have modified the continents’ bulk composition are essential for understanding the evolution of geodynamics and climate. Using novel data-analytic techniques we have extracted temporal trends in sediments’ protolith composition and weathering intensity from the largest available compilation of sedimentary major-element compositions: ∼ 15,000 samples from 4.0 Ga to the present. We find that the average Archean upper continental crust was silica rich and had a similar compositional diversity to modern continents. This is consistent with an early-Archean, or earlier, onset of plate tectonics. In the Archean, chemical weathering sequestered ∼ 25 % more CO2 per mass eroded for the same weathering intensity than in subsequent time periods, consistent with carbon mass-balance despite higher Archean outgassing rates and more limited continental exposure. Since 2.0 Ga, over long (> 0.5 Ga) timescales, crustal weathering intensity has remained relatively constant. On shorter timescales over the Phanerozoic, weathering intensity is correlated to global climate state, consistent with a weathering feedback acting in response to changes in CO2 sources or sinks.

Devonian in the North Qilian orogenic belt and Hexi Corridor developed terrestrial molasse of later stage of foreland basin caused by collision between the North China plate and Qaidam microplate. The foreland basin triggered a intense earthquake, and formed seismites and earthquake-related soft-sediment deformation. The soft-sediment deformation structures of Devonian in the eastern North Qilian Mts. consist of seismo-cracks, sandstone dykes, syn-depositional faults, microfolds (micro-corrugated lamination), fluidized veins, load casts, flame structures, pillow structures and brecciation. The seismo-cracks, syn-depositional faults and microfolds are cracks, faults and folds formed directly by oscillation of earthquake. The seismic dykes formed by sediment instilling into seismic cracks. Fluidized veins were made by instilling into the seismo-fissures of the fluidized sands. The load casts, flame structures and pillow structures were formed by sinking and instilling caused from oscillation of earthquake along the face between sandy and muddy beds. The brecciation resulted from the oscillation of earthquake and cracking of sedimentary layers. The seismites and soft-sediment deformations in Devonian triggered the earthquake related to tectonic activities during the orogeny and uplift of North Qilian Mts.

Three types of fatty acids—oleic acid, stearic acid, and 12-hydroxystearic acid—were used to disperse nano-sized bismuth powders in octane solvents. The surface characteristics of bismuth powders were modified to be hydrophobic in nature, and the bismuth-fatty acid formed on the surface. Stability property of the suspension was measured by ultraviolet-visible spectrophotometer. Results indicate that better suspension stabilization can be achieved when the 12-hydroxystearic acid is used. Adsorption behavior reveals that a greater affinity at the solid/liquid interface occurred for the 12-hydroxystearic acid than that for stearic acid or oleic acid. This observation suggests that the adsorption of 12-hydroxystearic acid may lead to a better packing of the acid molecules onto the solid surface than others and also results in better suspension stability. It is also evidenced by the results of theoretical calculation of potential energies that the colloidal stability of organic bismuth suspension is caused by fatty acid reducing the attractive interparticle potential and by steric repulsion mechanism.