Li X.,Wuhan University |
Li X.,CAS Qingdao Institute of Oceanology |
Li X.,Key Laboratory of Submarine Geosciences |
Fairweather L.,University of Aberdeen |
And 9 more authors.
Journal of Asian Earth Sciences | Year: 2013
The large Miocene-aged palaeo canyon that extents through the Qiongdongnan basin (QDNB) and Yinggehai basin (YGHB) of Northern South China Sea has been of considerable interest both economically and scientifically over the past decade. Stemmed from this, significant research has been employed into understanding the mechanism for its existence, incision, and sedimentary fill, yet debate remains. In the first case the canyon itself is actually quite anomalous. Alone from the size (over 570. km in length and more than 8. km in width (Yuan et al., 2009)), which is considerably more than most ancient deep-water channels (REFS), the canyon's sedimentary fill is also distinctly different. Some explanations have been given to explain the canyon's origin and existence, these include increased sediment supply from the Red River which is genetically linked to uplift of the Tibetan Plateau, lowstand turbidite and mass-transport activity, reactivation and dextral displacement of the Red River Fault zone inducing erosive gravity-flows, regional tilt of the QDNB and YGHB, paleo-seafloor morphology and seal-level fluctuations. With the application of new data obtained from interpretations of a large number of 2D seismic profiles, core and well log data, and tectonic and sedimentary analysis this contribution aims to: (1) Present models to explain the Canyon's sedimentary fill and basin plain deposits, which provided significant understanding of processes pre-, syn- and post-incision and; (2) review the plausibility and likelihood of each of the controlling mechanisms, hoping to shed light on this controversial aspect. We conclude that the final erosive event that shaped the canyon is dated at 5.5. Ma. The Canyon's unusual fill is a product of variation in the interaction between turbidity currents and MTD that blocked the canyon's axis, and the reduction in gravity flow energy through time; and therefore the complete succession represents one major erosive and cut event at 5.5. Ma and thereafter multi-gravity currents fills unlike in most slope channel-fills. © 2012 Elsevier Ltd.
Zhao J.,State Oceanic Administration |
Zhao J.,CAS Qingdao Institute of Oceanology |
Feng X.,State Oceanic Administration |
Shi X.,State Oceanic Administration |
And 9 more authors.
Marine Pollution Bulletin | Year: 2015
Organic and inorganic sedimentary parameters in and off the Changjiang Estuary have been analyzed to reconstruct historical trends in eutrophication and hypoxia over the last century. The lipid biomarker concentrations in the Changjiang Estuary mud area (CEMA) indicated eutrophication accelerated after the 1970s. Meanwhile, Mo/Al indicated hypoxia has increased since 1960s. Eutrophication and hypoxia in the CEMA are primarily a result of the dramatically increased load of terrestrial nutrients from the Changjiang to the East China Sea. The lipid biomarker concentrations in the southwest Cheju Island mud area (SCIMA) showed primary production is controlled mainly by changes in regional climate and marine current. No significant hypoxia occurred in the SCIMA over the past century as indicated by Mo/Al. Therefore, geochemical indicators of eutrophication and hypoxia revealed different patterns between the CEMA and SCIMA, suggesting the role of river-derived nutrients in sustaining eutrophication and hypoxia in the CEMA since the 1960s. © 2015 Elsevier Ltd.
Ge Q.,Wuhan University |
Ge Q.,Key Laboratory of Submarine Geosciences |
Chu F.,Key Laboratory of Submarine Geosciences |
Xue Z.,North Carolina State University |
And 3 more authors.
Acta Oceanologica Sinica | Year: 2010
Core ZHS-176 contains the paleoenvironmental records from the northern South China Sea (NSCS) since the Last Glacial Maximum (LGM). A coupled approach based on clay mineral assemblages, planktonic foraminiferal oxygen and carbon isotopes, and calcium carbonate content is used to trace the sources of the fine-grained sediment and to investigate the paleoenviornmental evolution in this area. Clay mineral assemblages are dominated by illite (average about 39%) and chlorite (about 27%), which comes mainly from Taiwan and the East China Sea. Kaolinite, which accounts for about 13%, comes mainly from the Zhujiang (Pearl) River, and Luzon Island is the main source for smectite (about 21%). The planktonic foraminiferal oxygen isotopic oscillations during the last glacial period are coeval with climate variations recorded in the Greenland ice core and Western Pacific sediment. These variations include the LGM, Heinrich event 1, Bφlling-Allerφd (B/A), and Younger Dryas. For the Holocene, three periods of strong precipitation (S1-S3) and three periods of weak precipitation (W1-W3) are identified. The oxygen isotopic record exhibits correlation with climate records from distant regions, including the high-latitude Northern Hemisphere, providing evidence for global tele-connection among regional climate. A brief, negative planktonic foraminiferal carbon isotopic excursion during B/A reflects increased methane released from marine gas hydrate due to the rapid warming of the water. By comparing calcium carbonate content curves of the core ZHS-176 with these of other five boreholes lying above the lysocline, a remarkable low calcium carbonate event is found during the early Holocene in NSCS. © The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2010.
Dong Y.P.,Zhejiang University |
Dong Y.P.,Research Center for Structures in Oil and Gas Bearing Basins |
Shen Z.Y.,Zhejiang University |
Shen Z.Y.,Research Center for Structures in Oil and Gas Bearing Basins |
And 9 more authors.
Acta Petrologica Sinica | Year: 2011
The Daba Shan thrust belt has very complex structures, and could be divided into two parts by the Chengkou-Fangxian fault. The north part (North Daba Shan) is regarded as the conjunction between the Soulh Qinling Orogen and the Upper Yangtze block, while the south part (the South Daba Shan) is a typical thrust-fold belt. In this paper, we focus on the structures of the South Daba Shan thrust-fold belt. The result indicates that it has multi-level and multi-stages deformation. The upper system is controlled by detachment along the gypsum layers in the limestone of the lower Triassic Jialingjiang Formation, and nearly all the Mesozoic strata are involved into the deformation. While the lower system is confined between two detachment surfaces; The gypsum layers in the lower Triassic Jialingjiang Formation and the shale in the Sinian. We accomplish three comprehensive regional geological sections, as well as their balance restoration sections, across the South Daba Shan based on geophysical data and Field investigation. According to them, we study in detail the structure and distribution of the upper and the lower thrust systems, their geometric and kinematic characteristics, and the spatial relationship between the Daba Shan and the Chuandong thrust-fold belts. We conclude that the South Daba Shan thrust belt is a complex multi-level thin-skinned thrust system with strong deformation and shortening.
Han X.,Key Laboratory of Submarine Geosciences |
Han X.,State Oceanic Administration |
Shi J.,Ocean University of China |
Zheng M.,State Oceanic Administration |
And 8 more authors.
OCEANS 2013 MTS/IEEE - San Diego: An Ocean in Common | Year: 2013
During Younger Dryas period (12.9∼11.6 cal. ka), the sea level oscillates at about -66m depth contour in the continental shelf seas in eastern China and the seawater gets into the south of present North Yellow Sea. So Yellow Sea became a long narrow channel gulf. To simulate the tidal current of this special gulf, Environmental Fluid Dynamics Computer Code (EFDC) was used in this paper. The calculation combines curvilinear orthogonal coordinates in the horizontal direction with Sigma mapping coordinates in the vertical direction, and it uses a method which transforms a problem from three-dimensional into two-dimensional. The results show that the tidal current is still very strong in Yellow Sea during Younger Dryas period, entering the special gulf along the right side entrance. From shallow both sides to deep centre, rotating flow changes reciprocating flow. Under the effect of reciprocating flow, the floor is eroded and the mud and sand are carried away. Progressive wave turns into rotating wave and two ateliotic amphidromic points appear on the western side of the gulf after tidal wave coming into Yellow Sea. At the same time, the tidal residual current flows towards southeast and east at relatively high velocity while at the west and interior gulf and it becomes weak near the entrance. The current may carry the bottom sediment and discharges them at the location of present mud sediment zone in north East China Sea. But at eastern Yellow Sea the tidal residual current flows to north and forms an anticlockwise circulation at centre of the eastern gulf which is corresponding to the eddy mud zone in Southeast Yellow Sea. The anticlockwise circulation captures suspended sediment and may gestate the present mud sediment zone. The extension direction of tidal sand ridges and the size composition of the tidal current sand in East South Yellow Sea have a close relationship with the tidal current field of the ancient Yellow Sea, so the fluctuating lesser sea level changing and the relative stable tidal current field are the favorable factors for the tidal sand ridges during Younger Dryas Episode in ancient Yellow Sea. It can be said that the ocean current, tidal current and tidal residual current figure the pattern of present Yellow Sea during Younger Dryas Period. © 2013 MTS.
Zhao J.,Key Laboratory of Submarine Geosciences |
Zhao J.,State Oceanic Administration |
Chu F.,Key Laboratory of Submarine Geosciences |
Chu F.,State Oceanic Administration |
And 5 more authors.
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2015
A factorial kriging analysis was conducted on seven heavy metal elements, Cd, Ni, Cu, Zn, Pb, Cr, As, of 388 surface samples collected from western Pearl River Estuary to study the spatial structure characteristics of the heavy metal elements, identify and separate spatial principal components at different spatial scales, and discuss the provenance of heavy metal elements and the influencing factors. The results show that the heavy metals exist spatially in three scales: nugget scale, spherical structure with a range of 60 km (local scale), and spherical structure with a range of 160 km (regional scale). According to the distribution of the regional factor(F1 and F2) score, high-value areas of F1(Zn, Cr, Ni, Cu)and F2(As) at local scale reflect “bull-eye like” distribution in estuary and harbor of coastal land. This suggests the potential anthropogenic pollution area of Zn, Cr, Ni, Cu and As. The eastern coast of Leizhou Peninsula is most likely the area of heavy metal pollution. The spatial distribution of the heavy metal elements at local scale is dominated by the local terrain or current; and their different spatial distribution between As and Zn, Cr, Ni, Cu is due to their different element geochemical behavior. The regional factors F1 (Zn, Cr, Ni) and F2(As) at regional scale indicate the influence of terrigenous parent rock, in which Zn, Cr, Ni are derived primarily from the parent rock from the mainland of South China; while As is derived primarily from the parent rock of Hainan Island. The high-value areas of F1 and F2 at regional scale show “slice-like” distribution extending from coast towards deeper sea overall in NNE direction; which is due to sea-level changes and the regional ocean circulation in NNE direction. © 2015, Jilin University Press. All right reserved.
Bian G.,Troops 91550 |
Bian G.,Key Laboratory of Submarine Geosciences |
Bian G.,Dalian Naval Academy |
Zhai G.,Naval Institute of Hydrographic Surveying and Charting |
And 5 more authors.
Cehui Xuebao/Acta Geodaetica et Cartographica Sinica | Year: 2014
The properties of harmonic function are studied, and it is proved that Bm is a pseudo-harmonic function. Based on the use of stable vertical derivatives, a stable algorithm is presented to perform downward continuation applying improved Taylor series approximation. Furthermore, the problem of edge effects could be settled out using grid extension to the four directions with half a cosine function before the vertical derivative calculation. The effectiveness of the suggested algorithm has been illustrated by real magnetic data from an airborne and seaborne magnetic survey. The conclusion shows that the presented technique can be employed to perform stable downward continuation of total field magnetic data and provide better results than other techniques based on fast Fourier transformation (FFT) or on normal Talor's series or integral-iteration method when the data is noise-free, and almost the same as integral-iteration method if the data contains certain noise.
Liang Y.-Y.,State Oceanic Administration |
Liang Y.-Y.,Key Laboratory of Submarine Geosciences |
Li J.-B.,State Oceanic Administration |
Li J.-B.,Key Laboratory of Submarine Geosciences |
And 6 more authors.
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2014
Based on the analysis of the full-coverage and high-resolution multibeam data of 49-51°E located between the Indomed and Gallieni fault zone of the Southwest Indian Ridge (SWIR), together with regional topography and other geophysical data, we discuss the magmato-tectonic dynamic model of this area segmentedly using the method of morphotectonics, then attempt to deduce the evolution of the entire Indomed-Gallieni segment since about 10 Ma ago further. It is concluded that segments 28 and 29 now follow a typical magma supply model of ultraslow spreading ridges, and have a low magma supply. As a result, they are under an asymmetric spreading by the control of large deep axial asymmetric faults. The volcanic constructions formed at the axis mainly accreted towards the north, and produced volcanic morphology there, while at the south flank hosts numerous large blocks due to the strong extension, and detachment faults may develop commonly there. Segment 27 has a shallow water depth, densely distributed volcanoes, without an axial valley, showing a robust magmatism in spite of an ultraslow spreading rate. The Indomed-Gallieni high terrain is resulted from a magma increase event, but we do not think it is because of the effect of the Crozet hotspot as mentioned in some literature. At present, however, segments 28 and 29 and other part of the Indomed-Gallieni segment have no longer been affected by this magma increase event, and has restored to normal ultraslow spreading evolution evidenced by its topography, while segment 27 is the only area still being affected, whereas its intensity and extent are decreasing. Segments 28, 29 and 27 are all experiencing a similar magma supply variation, during which ridge-shaped volcanic construction formed at the axis while magma supply was high, which was disrupted when magma supply became low. However, as with much larger magma flux, segment 27 behaved quite differently from segments 28 and 29 in the splitting pattern, period length and intensity of tectonic activity.
Luo X.,State Oceanic Administration |
Luo X.,Key Laboratory of Submarine Geosciences |
Gao J.,State Oceanic Administration |
Gao J.,Key Laboratory of Submarine Geosciences |
And 8 more authors.
23rd International Technical Meeting of the Satellite Division of the Institute of Navigation 2010, ION GNSS 2010 | Year: 2010
Nowadays, using kinematic PPP to determine tidal level is a hotspot in the field of marine surveying. This paper studies kinematic PPP positioning method and how to determine the tidal height use PPP and satellite altimeter data. In our experiments, degree of compliance of tidal height, which obtained from measurements and from model, increases in sequence as distance apart from seashore increases. The result dictated that combination of PPP and altimeter data is a feasible method to determine tidal height.