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Xu Z.-J.,Jilin University | Cheng R.-H.,Jilin University | Zhang L.,Guangzhou Bureau of Marine Geology Survey | Wang L.-L.,Guangzhou Bureau of Marine Geology Survey
Journal of Central South University | Year: 2013

Southwest Fujian area has experienced a large-scale transgression- regression cycle in Late Triassic-Middle Jurassic and the maximum transgression has taken place in Early Jurassic. The migration and enrichment of geochemical element in the continuous fine-grained sediments in the basin recorded the paleosalinity and the paleodepth. The changes of paleosalinity and paleodepth indicate the sea (lake) level relative change in every period of Late Triassic-Middle Jurassic in southwestern Fujian. The relative change curve of sea (lake) level in southwestern Fujian is established based on the m value (m=100×w(MgO)/w(Al2O3)) and the ratios of w(B)/w(Ga), w(Sr)/w(Ba) and w(Ca)/w(Mg). The curve indicates that level I sea-level relative change in southwestern Fujian is composed of the transgression in Late Triassic-Early Jurassic and the regression in the late period of Early Jurassic-Middle Jurassic. The level III sea-level relative change is frequent, which is composed by the lake level descent-lake level rise-lake level descent of Wenbin Shan formation in Late Triassic, the regression-transgression-regression of Lishan formation in Early Jurassic and the lake-level rise-lake level descent-lake level rise-lake level descent of Zhangping formation in Middle Jurassic. The transgression-regression cycle in southwestern Fujian is significantly controlled by the sea-level change in the north of South China Sea. The relative change curve trends of the level I sea-level in the north of South China Sea and the one in southwestern Fujian are the same. The maximum transgressions both occur in Early Jurassic. The level III sea-level curve reflects the fluctuation of a transgression and two regressions in the early period of Early Jurassic. © Central South University Press and Springer-Verlag Berlin Heidelberg 2013.


Xu Z.,Jilin University | Cheng R.,Jilin University | Wang L.,Guangzhou Bureau of Marine Geology Survey | Zhang L.,Guangzhou Bureau of Marine Geology Survey | And 2 more authors.
Acta Petrologica Sinica | Year: 2013

The Wenbinshan Formation, Lishan Formation and Zhangping Formation in Upper Triassic-Middle Jurassic in southwestern Fujian experienced a large-scale transgressive-regressive event. The geochemical characteristics which is showed by the major element analysis and ICP-MS trace element and rare earth element analysis show that the source rocks of the set of sediments are mainly sedimentary rock and granite (Rb> 100×10-6; K2O>1%; Hf = 5. 38 × 10-6 ∼ 14. 17 × 10-6; La/Th = 1. 64 ∼4. 94). The source rocks of the Wenbinshan Formation and Lishan Formation sediments are from the sedimentary rock and granite of the passive continental margin source area and acidic arc source area (Rb>300× 10-6; K20>2%; Hf = 3. 75 × 10-6 ∼6. 64×10-6; La/Th = 2. 73 ∼4. 21). The source rocks of Zhangping Formation are from the granite in the acidic arc source area and the mixture source area of felsic and mafic. The studies of the compositions of the sandstone framework have shown that Wenbinshan Formation source material are mainly from the volcanic arc orogen; Lishan Formation and Zhangping Formation are from the volcanic arc orogen and the magmatic arc source area. It is consistent with the source area showed by the mudstone geochemistry. The association of the lithology and facies in different ages, the geochemistry characteristics of the mudstone and the mineral composition of the sandstone and the locations of the samples in Zr-Th, La-Th-Sc, Th-Co-Zr/10 tectonic setting discrimination diagrams have showed that Wenbinshan Formation sediments deposited on the back-arc extensional basin with the characteristics of both a passive continental margin and a continental island arc (EREE=22. 51 × 10-6-152. 6×10-6; LREE/HREE =7. 21-15.01, SEu =0. 69∼0. 90; La/Yb = 5. 64 ∼ 16. 93; (La/Yb)N = 3.66∼ 10.99). Lishan Formation sediments deposited on the active continental margin which is near the continental island arc (XREE = 140.4×10 -6-335.5 × 10-6, LREE/HREE =9. 52 ∼15. 90, SEu =0. 48-0. 62, La/Yb = 11. 04∼21. 13; (La/Yb) N = 7. 17 ∼ 13. 72). It is also the back-arc basin squeeze with the characteristics of a passive continental margin (XREE = 115. 4 × 10 ∼ 383. 4 × 10 -6, LREE/HREE = 8. 30 ∼ 20. 27,δEu = 0. 55-0. 67, La/Yb = 8. 42 ∼ 30. 12; (La/Yb) N = 5. 47 ∼ 19. 56). Zhangping Formation sediments deposited on the back-arc basin squeeze with the characteristics of an active continental margin (X REE = 98. 34×10 -6-260.5 × 10-6, LREE/HREE =11.28-19.38, SEu = 0. 56∼0.64, La/Yb = 10. 19 ∼23.91; (La/Yb) N = 6. 62 ∼ 15. 52) which is near the continental island arc.


Xu Z.,Jilin University | Cheng R.,Jilin University | Wang L.,Guangzhou Bureau of Marine Geology Survey | Zhang L.,Guangzhou Bureau of Marine Geology Survey | Li F.,Jilin University
Acta Petrologica Sinica | Year: 2010

The Tangxia Formation of Middle Jurassic in Dongguan, Guangdong Province, is a kind of lacustrine sediments in rich of tuffaceous materials. The changes of Sr/Ba, B/Ga and Ca/Mg have a positive correlation with the changes of paleosalinity. The result of the ratios is based on the whole rock analysis and ICP-MS trace element analysis of the samples. The characteristics of those shows that sediments of Tangxia Formation ares salty lacustrine sediments. The paleosalinity of Tangxia Formation descends gradually from bottom to top, and the lake depth reduces as well. The value of δCe and the ratio of (La/Yb)N to the samples are got through the ICPMS trace element analysis. The value of δCe is between 0.81 and 1.31. The ratio of (La/Yb)N is obvious larger than 1 or smaller than 1. The value of δCe and (La/Yb)N reflects that the depositional rate of lake sediments was slower during the main stage of development of Tangxia Formation except the initial and final stages with a relatively faster rate. The values of P and Sr/Cu reflect their enrichment and migration, controlled by the climate. The average of P is 0.205 × 10-2 and the average of Sr/Cu which achieved lowest value 1.42 × 10-6 in middle and late stages is larger than 4.0 × 10-6. The averages are caused by the climate of Tangxia Formation, which was mainly hot-arid climate and the warm-humid climate only in middle and late stages. The Tangxia Formation is salty lacustrine sediments with slow depositional rate and hot-arid climate. The discrimination diagrams of Zr-Th and La-Th-Sc, REE and the regional tectonic analysis show that the tectonic setting of Dongguan area of Middle Jurassic was back-arc basin of active continental margin. Affected by the extension, Dongguan area developed into the rift lake basin in the back-arc. La/Yb- ΣREE source rock discrimination diagram of the mudstones shows that source rock were basalt, granite and sedimentary rocks.


Xu Z.,Jilin University | Cheng R.,Jilin University | Wang L.,Guangzhou Bureau of Marine Geology Survey | Zhang L.,Guangzhou Bureau of Marine Geology Survey
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2015

The whole rock analysis, the ICP-MS trace, the rare earth elements test, and the mineral composition analysis were made to the mudstone and sandstone samples collected from Jiexi Huizhai Upper Triassic Xiaoshui Formation and Huizhou Huangdong Lower Jurassic Jinji Formation. Based on the changes of the element content and the ratios, the water was in a reductive and anaerobic environment as a whole; and it was mainly in a dry and hot climate during the Late Triassic Xiaoshui Formation in Jiexi area and the Early Jurassic Jinji Formation in Huizhou area in east Guangdong. The ∑REE is high, the LREE is rich (LREE/HREE are 10.86 and 15.63), and the HREE is more stable (∑HREE are 6.09×10-6 and 7.99×10-6) with a negative Eu anomaly (δEu are 0.67 and 0.87) in Xiaoshui Formation. The LREE is rich (LREE/HREE=7.29-10.03), the HREE is more stable (∑HREE=(15.39-19.72)×10-6) with a negative Eu anomaly (δEu=0.59-0.65) in Jinji Formation. The mudstone REE distribution diagram and the source rock discrimination diagram show that the Xiaoshui Formation and Jinji Formation source rocks were from the sedimentary rocks, granite, and basalt of the upper-crust. The sediment source rocks of Xiaoshui Formation in the lower part were deeper than the ones in the upper part. The sediment source rocks of Jinji Formation in the upper part were deeper than the ones in the middle-lower part. Based on the Dickinson diagram, the discrimination diagrams of K2O/Na2O-SiO2, Zr-Th, La-Th-Sc, Th-Co-Zr/10, and the REE characteristics values, the tectonic background of Late Triassic Jiexi area was the back-arc extensional basin. It presents the feature of a passive continental margin and also the continental island arc (transformed by the Andean continental margin arc). The provenance was from the volcanic arc orogenic belt. Huangdong area was the back-arc extrusion basin in Early Jurassic with the passive continental margin characteristics. The sediment provenance is from the cut magmatic arc. ©, 2015, Jilin University Press. All right reserved.


Wang L.,Guangzhou Bureau of Marine Geology Survey | Xu Z.,Jilin University | Cheng R.,Jilin University | Hu X.,Guangzhou Bureau of Marine Geology Survey | Liu H.,Jilin University
Geotectonica et Metallogenia | Year: 2015

The X-drilling cores of the North Yellow Sea basin reveal two sets of Mesozoic clastic rocks, which are the dark rocks in lower part and the red rocks in upper part, respectively. There are two layers of volcanic rocks at the bottom and the upper part of the dark rock unit. The volcanic rocks at the bottom part are trachytic dacite while rocks at the upper part are clastic dacite. The zircon grains from the upper and lower units of volcanic rocks are euhedral-subhedral columnar crystals and show oscillatory zoning on cathodoluminescence images. 22 tests of zircons in the trachytic dacite from the bottom part yield an age of 141-151 Ma, with weighted mean 206Pb/238U age of 145±2 Ma. Whereas 18 tests of zircons from the sample at the upper part give 206Pb/238U ages around 139-149 Ma with weighted mean 206Pb/238U age of 141±2 Ma, which implies that the X well volcanic rocks belong to Late Jurassic-Early Cretaceous. Comparing with the age and geochemical characteristics of the Mesozoic igneous rocks in Shandong peninsula, we suggest that the igneous rocks from both the North Yellow Sea basin and Jiaolai basin were formed under same dynamic setting, i.e., the subduction related volcano arc and back-arc extension. ©, 2015, Science Press. All right reserved.

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