Tectono-magmatic controls on decratonic gold deposits

<jats:title>Abstract</jats:title><jats:p>Magmatic-hydrothermal gold–copper deposits in post-subduction settings represent essential targets for mineral exploration, but controls on their formation remain controversial. The early Cretaceous lode Au districts that formed during lithosphere destruction of the North China Craton provide an ideal opportunity to better understand the key tectono-magmatic factors responsible for the genesis of Au-rich deposits in post-subduction settings. Here, we present a LA-ICP-MS study of silicate melt inclusions and sulfide inclusions from ore-related mafic to intermediate rocks in the central Taihangshan Au district in the interior of the North China Craton to constrain the content and evolution of magmatic ore metals ± volatiles. The results, combined with numerical modeling, suggest that the ore-related magmas contained only a few ng/g Au, which is similar to the Au content of non-mineralization-related mafic to intermediate magmas worldwide. The low Au content of the lode Au-related magmas suggest that large volumes of magmas had to accumulate in the middle to lower crust through trans-lithospheric fault systems to produce the lode Au deposits. It is further suggested that the lode Au-related magmas were alkali-rich, hydrous, oxidized and relatively rich in sulfur and chlorine (mafic melt inclusions contain 0.14‒0.24 wt% S and 0.1‒0.2 wt% Cl). These properties are considered critical for the generation of auriferous ore fluids. By comparing the tectono-magmatic setting of the giant Jiaodong Au province (~ 4000 t Au) with the central Taihangshan district (~ 150 t Au), we propose that the much larger total Au tonnage of the Jiaodong district results from the accumulation of a much larger volume of ore-forming magmas at deep crustal levels, induced by a stronger degree of lithosphere modification. In addition, given that the composition of lode Au-related magmas is similar to that of porphyry Cu–Au-related magmas, the lack of giant, early Cretaceous porphyry Cu–Au deposits in the North China Craton suggests that strong extensional settings favor the formation of lode Au deposits instead of porphyry Cu–Au deposits. The present study, therefore, has general implications for the genesis of Au-rich deposits in strongly extensional settings.</jats:p&gt

Comparison of Genetic Algorithm Based Support Vector Machine and Genetic Algorithm Based RBF Neural Network in Quantitative Structure-Property Relationship Models on Aqueous Solubility of Polycyclic Aromatic Hydrocarbons

AbstractA modified method to develop quantitative structure-property relationship (QSPR) models of organic contaminants was proposed based on genetic algorithm (GA) and support vector machine (SVM). GA was used to perform the variable selection and SVM was used to construct QSPR model. In this study, GA-SVM was applied to develop the QSPR model for aqueous solubility (Sw, mg•l-1) of polycyclic aromatic hydrocarbons (PAHs). The R2 (0.980), SSE (2.84), and RMSE (0.25) values of the model developed by GA-SVM indicated a good predictive capability for logSw values of PAHs. Based on leave-one-out cross validation, the results of GA-SVM were compared with those of genetic algorithm-radial based function neural network (GA-RBFNN). The comparison showed that the R2 (0.923) and RMSE (0.485) values of GA-SVM were higher and lower, respectively, which illustrated GA-SVM was more suitable to develop QSPR model for the logSw values of PAHs than GA-RBFNN

Push-Out Test on SCS sandwich composite members with various concrete cores and shear connectors

The development of Steel-Concrete-Steel1(SCS) sandwich composite construction has accelerated in recent decades. SCS members have been used as lightweight key components in buildings, bridges, and other structures in civil engineering applications because of its features and advantages. Slippage in SCS sandwich composite member could happen in between concrete and steel plates under compressive loading or in a column under axial load. As a result, the composite action could be reduced and thus decreasing the load-bearing capacity. This research is to explore the failure modes of the SCS specimens and to study the influences of various parameters such as concrete type and shear connector type on the interface behavior in SCS sandwich composite column by carrying out a series of push-out tests

EFFECT OF WEARABLE FITNESS WATCH ON PHYSICAL ACTIVITY IN SCHOOL CHILDREN WITH OVERWEIGHT

Overweight and obesity in children and adolescents is a significant health problem, and lack of physical activity may be a factor related to obesity. In this study, we explored the wearable fitness watch to monitor the physical activity promoted situation of overweight and obese schoolchildren. Participants were overweight schoolchildren divided into two groups, the study group (n=41) and the control group (n=44). In the control group, the wearable fitness watch only displays the time. In the study group, each week, participants set up the goal, which increases the steps by 10% from baseline steps to reach 10,000 steps. The ANOVA is adopted to analyze the parameters such as the average daily number of steps, moderate to vigorous physical activity (MVPA). The results indicated the study group increase and improved daily walking steps and MVPA accumulation time in 8 weeks. The wearable fitness watch can help to promote the physical activity of overweight children