Petro-geochemistry, LA-ICP-MS zircon U-Pb chronology and tectonic implications of monzonitic granite and diabase: taking the middle of Nanxiong Fault Belt in the Nanxiong Basin within the Northern Guangdong as an example.

In order to study the geological characteristics and tectonic implications of the Nanxiong Fault Belt in the northern margin of Nanxiong Basin, nionzonitic granite and diabase in the middle of Nanxiong Fault Bet are taken as the research object. Based on the study of field geological exploration, petro-geochemistry and LA-ICP-MS zircon U-Pb chronology, the petrological characteristics, major element characteristics, trace element characteristics and chronological characteristics of monzonitic granite and diabase have been analyzed in detail. In addition, the petrogeneses and tectonic implications of mon- zoonotic granite and diabase have been strictly discussed. This result shows that the monzonitic granite in the middle of Nanxiong Fault Bet is peraluminous high-K calc-alkalic rock series with geochemical characteristics of S-type granite. The light rare earth elements(LREE) are remarkably enriched. The monzonotic granite samples are intensely enriched in Rb, Th, K, Sr, Pb and obviously depleted in Nb, Ta, Ti with an obvious negative anomaly. The LA-ICP-MS zircon U-Pub doing results of the monzonitic grant samples yield a ²⁰⁶ pb/²³⁸ U weighted mean age of (448.5 ± 6.8) Ma. This monzonotic granite belongs to syn-collision granitoids, the REE geochemical characteristics of which are similar to those of oceanic volcanic arc granite(VAG). This study indicates that the diabase in the middle of Nanxiong Fault Belt is a quasi-aluminous calc-alkainne rock series. The diabase samples are obviously enriched in Sr, Pb, Ta, Ti, Nb, Rb and evidently deleted in Pr, Sm, Gd, Tb, Ho. The ²⁰⁶ pb/²³⁸ U weighted mean age of (437.2 ± 3.5) Ma. The diabase samples have the trace element geochemical characteristics of enriched mid-oceanic ridge basalt(E-MORB), which are formed in the tectonic environment of mid-oceanic ridge near the trench. The magma is derived from the enriched mantic. It is evidently believed that there was a regional tectonic stress transformation from compression to extension during 448 to 437 Ma. And magma fractional crystallization is accompanied by the crus--derived material remitting and the participation of Hands in the process of the intense magnetic activity, undergoing the late mantic-derived magma intrusion. The research results provide the structural geological and chronological evidence for provenance analysis and the study of the relationship between granite bodies, offer the basic scientific references for further identification of characteristics of uranium mineralization and metallogeny, and have the application value for the research on tectonic implications and fault-controlling characteristics of Nanxiong Fault Belt. [ABSTRACT FROM AUTHOR]