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Crystal-size and spatial distributions of minerals in metamorphic rocks provide insight into their nucleation, growth environment, and the metamorphic evolution of their host rocks. Episodic nucleation and growth histories for garnets in eclogites from the DaNe orogen are revealed by variations in crystal size, geochemical zoning, and mineralogy of inclusions in garnets. The studied garnets show pseudo-lognormal crystal-size distributions (CSDs), prograde chemical zoning patterns indexed by mineral inclusions, and are mainly distributed at random. Constant growth rate for each episode is proposed based on the mineralogy of inclusions in garnets and the chemical zoning patterns. The CSD shapes were evaluated in terms of a size-dependent proportionate growth model and a thermally accelerated, diffusion-controlled model but neither is consistent with the geochemical data and the concordant occurrence of mineral inclusions in garnet. Initial increasing nucleation rate followed by a subsequent, medial stage of nearly constant growth and finally declining nucleation rate is inferred from the CSD data. This study suggests that linking chemical analysis with textural analysis is crucial to avoid misleading interpretation solely through CSD shapes of minerals in metamorphic rocks. Keywords: Garnet, crystal size, zoning, growth, DaNe

Detailed electron- and ion-microprobe analyses were carried out on atoll-shaped and normal garnets in ultrahigh-pressure (UHP) metamorphic eclogite from Dabie, east-central China. Compositional profiles of both normal garnets and rings of atoll garnets show well-preserved growth zoning with a decrease in Mn, Ca, and heavy rare earth elements (HREEs), and an increase in Mg toward rims. Manganese and middle rare earth element (MREE) enrichments are observed near garnet rims. Island- and peninsula-shaped garnet inside atolls are homogeneous in major elements and show the same composition as garnet rims, whereas the HREE concentrations are similar to those of the normal garnet cores. Electron back-scatter diffraction (EBSD) analyses show that the island- and peninsula-shaped garnet fractions inside atolls have crystallographic orientations identical to that of the atoll rings. These observations suggest that the atoll garnets were formed by the consumption of earlier-formed cores by fluid released from both hydroxyl exsolution from the nominally anhydrous minerals (NAMs) and lawsonite decomposition at the onset of exhumation, (i.e., garnet breakdown was from the inside and re-growth from outside to inside). Though somewhat restricted, this study reveals that because garnet and zircon act as sinks for HREEs and Zr, respectively, the majority of released HREEs and Zr were likely re-incorporated into newly grown garnet and zircon during the Dabie UHP metamorphic slab exhumation. Keywords: Atoll garnet, fluid, eclogite, Dabie

The post-orogenic evolution of the Dabie Shan in eastern China is examined. Results and interpretations of the low-temperature post-orogenic history of Dabie Shan are also presented using apatite and zircon (U-Th)/He (AHe and ZHe) and apatite fission-track (AFT) thermochronometry.

In order to improve the wearing comfort and bearing effectiveness of the exoskeleton, based on the prototype and working mechanism analysis of a relaxation wearable system for knee exoskeleton robot, the static optimization synthesis and its method are studied. Firstly, based on the construction of the virtual prototype model of the system, a comprehensive wearable comfort evaluation index considering the factors such as stress, deformation and the proportion of stress nodes was constructed. Secondly, based on the static simulation and evaluation index of system virtual prototype, multi-objective genetic optimization and local optimization synthesis of armor layer topology were carried out. Finally, the model reconstruction simulation data confirmed that the system had good wearing comfort. Our study provides a theoretical basis for the bearing performance and prototype construction of the subsequent wearable system.