Indicating significance of Cenozoic zircon fission track ages of the Jiyang depression to its provenance and tectonic background
Liu Shilin1,2, Xiao Huanqin3, Lin Ge2, Zheng Herong1, Wang Yi1
1. Exploration & Production Research Institute of SINOPEC, Beijing 100083;
2. Guangzhou Institute of Geochemistry, CAS, Guangzhou 510640;
3. Shengli Oilfield Company of SINOPEC, Dongying, Shandong 257060
Zircon fission track analyses of sediments of sedimentary basins can be used to trace its provenance characters and tectonic evolutional history.Central ages of zircon fission tracks of 9 Cenozoic sandstones from the Jiyang depression arrange from 183.1±15.0 Ma to 100.1±5.6 Ma,and all the single zircon grain age is bigger than its strata depositional age.Multiple component analyses of zircon fission track ages were calculated to the 6 samples which were not passed by χ2-Test,and the results show that most sandstone samples mainly consist of two age components.As a whole,single component of zircon fission track ages of the 9 sandstones show a good coherence,and these can be concluded into four components which arranges from 389.1±5.1 Ma to 272.7±14.6 Ma(P1), 238.1±7.8 Ma to 203.6±6.6 Ma(P2), 179.3±13.9 Ma to 96.8±17.8 Ma(P3),and 80.3±15.7 Ma to 55.3±6.0 Ma(P4)respectively.The four components record the entire annealing ages of zircon grains in the Late Paleozoic,Triassic,Late Cretaceous-Paleocene and Early Cretaceous respectively.Combined with regional geological background,it can be concluded that volcanic rocks and volcano-clastic rocks of the Upper Jurassic to Lower Cretaceous strata which were formed due to the intense tectono-magmatic activation of the Middle Yanshannian Movement are the chief provenance to Cenozoic strata of the depression; meanwhile,the tectono-magmatic activations which are attributed to the Hercynian,the Indosinian,and the Late Yanshannian to Early Himalaya Movements also have a few provenance contribution to those of the Jiyang depression.