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| 1 | Cretaceous Deepwater Lacustrine Dedimentary Sequences from the Northernmost South China Block, Qingdao, China显示文摘A sequence of terrigenous siliciclastic rocks crop out at Baxiandun, Qingdao, near the Mesozoic collisional boundary between North China block(NCB) and South China block(SCB). These low-grade metamorphosed siliciclastic rocks are dominated by greywacke with shale, manganiferous fine-grained sandstone, arkose and conglomerate layers. There are two basic interpretations about the formation of these rocks. One considered that this sequence was formed within NCB, and is part of the Cretaceous Laiyang Group and Qingshan Group fluvial facies and volcanic debris facies, as shown on the Shandong Regional Geological Map. Another opinion suggested that these rocks represent turbidity depositional systems in the slope and the basin facies was mainly deposited in Ordovician. Based on field observation, petrological analysis, and most importantly, geochemical results in this study, the sedimentary strata at Baxiandun Section mainly consist of siltstone, sandstone and mudstone lithologies. They are dominated by deepwater debris and turbidity deposits in the slope and base of a lake. The U-Pb detrital zircon dating of the rocks at the Baxiandun Section indicates that the source rocks are very complex and their ages are varied from Archean to Early Cretaceous. The youngest age of the terrigenous detritus could represent the age of the sedimentary strata. Therefore, we infer that the sedimentary rocks belong to Early Cretaceous deepwater lacustrine sedimentary sequences and have multiple sources origined from the erosion of the Sulu UHP orogen and South China block margin. | Tuoyu Wu Yongtao Fu | 2014 | Journal of Earth Science2014，25，2： | 6 |
| 2 | Sediment Compaction and Pore Pressure Prediction in Deepwater Basin of the South China Sea: Estimation from ODP and IODP Drilling Well Data显示文摘Overpressure in deepwater basins not only causes serious soft sediment deformation, but also significantly affects the safety of drilling operations. Therefore, prediction of overpressure in sediments has become an important task in deepwater oil exploration and development. In this study, we analyze the drilling data from ODP Leg 184 Sites 1144, 1146, and 1148, and IODP Leg 349 Sites U1431, U1432, U1433, and U1435 to study the sediment compaction and controls in the northern South China Sea. Sedimentation rate, sediment content, distribution area, and buried depth are the factors that influence sediment compaction in the deepwater basin of the South China Sea. Among these factors, the sediment content is the most important. The fitted normal compacted coefficients and mudline porosity for an interval of 50 m shows disciplinary variation versus depth. The pore pressure predicted from different fitted results shows varying overpressure situations. The normal compaction trend from Site 1144 reflects the porosity variation trend in stable deposition basins in the northern South China Sea. The predicted pore pressure shows overpressure at Site 1144, which is attributed to compaction disequilibrium. Nevertheless, the mixed lithology column may influence the predicted overpressure at Site 1148, which is responsible for the confusing result. Above all, we find that sediment compaction should serve as a proxy for pore pressure in the deepwater basin of the South China Sea. | XIE Yangbing WU Tuoyu SUN Jin ZHANG Hanyu WANG Jiliang GAO Jinwei CHEN Chuanxu | 2018 | Journal of Ocean University of China2018，17，1： | 2 |
| 3 | Petrology and geochemistry of serpentinized peridotites from Hahajima Seamount in Izu-Bonin forearc region显示文摘Serpentinites,which contain up to 13 wt%of water,are important reservoirs for chemical recycling in subduction zones.In the past two decades,forearc mantle serpentinites were identified in different locations around the world.Here,we present petrology and whole rock chemistry of ultramafic and mafic rocks dredged from the Hahajima Seamount,which is located 24–40 km west to the junction of the Izu-Bonin Trench and the Mariana Trench.Nearly all the collected samples are extensively hydrated,and olivine grains in ultramafic rocks are replaced by serpentine minerals,with only one sample preserving remaining trace of orthopyroxene.Our new results show that the Hahajima serpentinized peridotite samples are all MgO-rich(~42 wt%),but have low contents in Al2O3,CaO,rare earth and high field strength elements,which is consistent with the overall depleted character of their mantle protoliths.Model calculations indicate that these Hahajima peridotite samples were derived from 10%–25%partial melting of the presumed fertile mantle source,which is generally lower than those of peridotites from Torishima Forearc Seamount,Conical Seamount and South Chamorro Seamount(mostly>25%).All the serpentinites from these four forearc seamounts show strong enrichment in fluid-mobile and lithophile elements(Li,Sr,Pb and U).In details,Hahajima Seamount serpentinites do not have obvious enrichment in Cs and Rb,and display remarkably high abundances of U.These observations indicate that the serpentinization of Hahajima peridotites occurred by addition of seawater or low temperature seawater-derived hydrothermal fluid,without or with little contribution from slab-derived fluids.The geochemical signature of serpentinites from Hahajima Seamount could be interpreted as the result of the combination of extensive partial melting and subsequent percolation of seawater through the mantle wedge. | Tuoyu Wu Liyan Tian Jinwei Gao Yanhui Dong | 2019 | Acta Oceanologica Sinica2019，38，11： | 0 |
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