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Cretaceous Granitic Magmatism in South-Central Vietnam: Constraints from Zircon U–Pb Geochronology

100%

Nguyen H. H. , Pham N. S. , Hoang V. L. , Carter A. , Bui V. H. , Bui H. B. , Trinh T. T. , Nguyen L. A.

tom no. 2

7--14

South-central Vietnam abundantly presents magmatic rocks with larger volumes of Cretaceous granitic rocks. In this study, zircon U–Pb geochronology of granite samples from the Deoca, Ankroet, and Dinhquan complexes in south-central Vietnam are utilized to investigate Cretaceous granitic magmatism. According to U–Pb analysis results, zircon ages of granitic rocks display the Deoca at ~113–92 Ma, the Ankroet at ~103–98 Ma, and the Dinhquan at ~97–113 Ma. The range of ages is narrow from 113 to 92 Ma, with most common ages date at ~100 Ma. Published data and our results display that Cretaceous granitic magmatism was active between ~87–118 Ma and most active at ~100 Ma in south-central Vietnam. Additionally, the Deoca and Dinhquan complexes show inherited ages in Triassic followed by Proterozoic and Carboniferous to Ordovician. The obtained ages indicate that Itype granitic rocks could be derived from melting of basement rocks. Our study suggests that I-type granitic rocks in south-central Vietnam were significantly intruded around 100 Ma.

A Lasso and Elastic-Net Regularized Generalized Linear Model for Predicting Blast-Induced Air Over-pressure in Open-Pit Mines

100%

Bui X. N. , Nguyen H. , Tran Q. H. , Bui H. B. , Nguyen Q. L. , Nguyen D. A. , Le T. T. H. , Pham V. V.

tom R. 21, nr 2/2

8--20

Air overpressure (AOp) is one of the products of blasting operations in open-pit mines which have a great impact on the environment and public health. It can be dangerous for the lungs, brain, hearing and the other human senses. In addition, the impact on the surrounding environment such as the vibration of buildings, break the glass door systems are also dangerous agents caused by AOp. Therefore, it should be properly controlled and forecasted to minimize the impacts on the environment and public health. In this paper, a Lasso and Elastic-Net Regularized Generalized Linear Model (GLMNET) was developed for predicting blast-induced AOp. The United States Bureau of Mines (USBM) empirical technique was also applied to estimate blast-induced AOp and compare with the developed GLMNET model. Nui Beo open-pit coal mine, Vietnam was selected as a case study. The performance indices are used to evaluate the performance of the models, including Root Mean Square Error (RMSE), Determination Coefficient (R2), and Mean Absolute Error (MAE). For this aim, 108 blasting events were investigated with the Maximum of explosive charge capacity, monitoring distance, powder factor, burden, and the length of stemming were considered as input variables for predicting AOp. As a result, a robust GLMNET model was found for predicting blast-induced AOp with an RMSE of 1.663, R2 of 0.975, and MAE of 1.413 on testing datasets. Whereas, the USBM empirical method only reached an RMSE of 2.982, R2 of 0.838, and MAE of 2.162 on testing datasets.