Braid-Delta Deposits from a Broad Shallow-Marine Setting: the Middle Member of the Kalpingtag Formation in the Central Tarim Basin

During the early Silurian, a transgressive and vast shallow sea with flat sea-floor covered the central Tarim Basin (the Tazhong area). The depositional environment of the middle member of the Kalpingtag Formation is controversial. In order to provide a basis for the prediction of reservoir sand, the sedimentary facies are recognized according to abundant core observations and de- scriptions combined with well-log analysis, isograms, seismic interpretations and regional sedimentary background. The middle member of the Kalpingtag Formation, which shows a retrograding sequence, is interpreted as braid-delta deposits influenced by mi- nor tidal reworking. The sources of clasts are from the southern uplift. The subaqueous braid-delta deposits in the study area have some characteristics quite different from the common deltas that generally deposit in marginal seas. Four facies grouped to a delta front association are recognized, ranging from distributary-channel (Facies A), front bar (Facies B), sand sheet (Facies C) and inter- distributary bay (Facies D). The distributary channels construct the sandbody framework of the delta front. Front bar deposits, which are fine-grained with low depositional dips, display a near-continuous sand strip around the entire periphery of the delta. Sand sheet deposits are mainly found in front of Facies B, gradationally contacting with the prodelta. The interdistributary bay is essentially the uppermost unit capping the channel sequence and generally made up of laminated and massive mudstones. The delta front deposits display extensive sheet-like bodies contrasting with the characteristic wedge shapes of common subaqueous delta bodies. The bi- modal cross-stratification and mud drapes in the fine- to medium-grained sandstone in the distal area are inferred to reflect high-energy tidal processes.

Effects of Reclamation on Soil Carbon and Nitrogen in Coastal Wetlands of Liaohe River Delta,China

To evaluate the influence of wetland reclamation on vertical distribution of carbon and nitrogen in coastal wetland soils, we measured the soil organic carbon(SOC), soil total nitrogen(STN) and selected soil properties at five sampling plots(reed marsh, paddy field, corn field, forest land and oil-polluted wetland) in the Liaohe River estuary in September 2013. The results showed that reclamation significantly changed the contents of SOC and STN in the Liaohe River estuary(P < 0.001). The SOC concentrations were in the order: oil-polluted wetland > corn field > paddy field > forest land > reed marsh, with mean values of 52.17, 13.14, 11.46, 6.44 and 6.16 g/kg, respectively. STN followed a similar order as SOC, with mean values of 1351.14, 741.04, 632.32, 496.17 and 390.90 mg/kg, respectively. Interaction of reclamation types and soil depth had significant effects on SOC and STN, while soil depth had significant effects on SOC, but not on STN. The contents of SOC and STN were negatively correlated with pH and redox potential(Eh) in reed marsh and corn field, while the SOC and STN in paddy field had positive correlations with electrical conductivity(EC). Dissolved organic carbon(DOC), ammonium nitrogen(NH_4^+-N) and nitrate nitrogen(NO_3~–-N) were also significantly changed by human activities. NH_4^+-N and NO_3~–-N increased to different degrees, and forest land had the highest NO_3~–-N concentration and lowest DOC concentration, which could have been caused by differences in soil aeration and fertilization. Overall, the results indicate that reed harvest increased soil carbon and nitrogen release in the Liaohe River Estuary, while oil pollution significantly increased the SOC and STN; however, these cannot be used as indicators of soil fertility and quality because of the serious oil pollution.

Phosphorus Behavior at Sediment-Water Interface in Coastal Wetland

[Objective] The aim was to explore the role of coastal wetlands in phosphorus fixation in the Yellow River Delta.[Method] The research analyzed phosphorus behavior at sediment-water interface by static water column test. [Result] The research concluded that phosphorus concentration was in the range of 0.051-0.322 mg/L in overlying water, and phosphorus was effectively removed by degradation and adsorption. The static water column test has demonstrated that phosphorus concentration of coastal wetlands plays the role of accumulation when phosphorus concentration is lower than 7 mg/L in overlying water of coastal wetlands. It is notable that substrates of overlying water all perform well in adsorption, and the adsorption reaches saturation if the concentration goes up to 10 mg/L. [Conclusion] Coastal wetlands would significantly adsorb and degrade phosphorus in overlying water, controlling phosphorus within a lower range.

乡村走出的巨人——杜桑·卢维都尔

18世纪末到19世纪初,位于加勒比海大安的列斯群岛中的海地岛上的人民揭竿而起,反对殖民统治和奴隶制度,经过十几年的艰苦斗争,终于赢得了海地的独立和奴隶的解放,为争取独立和自由的拉丁美洲各族人民树立了光辉的榜样。领导海地革命的黑人奴隶杜桑·卢维都尔的英名传遍了五洲四海。 1743年5月20日,杜桑在海地北部的一个种植园降生。该种植园座落在群山之中,拥有上千黑人奴隶,是海地最大的种植园之一。

Crustal structure of the northwestern sub-basin, South China Sea: Results from a wide-angle seismic experiment

The crustal structure of the northwestern sub-basin area of the South China Sea was modeled by inverting a wide-angle seismic survey line across the entire region and on both sides of its bounding continental margins. The survey line extended over 484 km. A total of 14 Ocean Bottom Seismometers (OBS) were deployed at intervals of 30 km to record air-gun array sources with a combined volume of 5160 in 3 . The crustal velocity structure of the northwestern sub-basin area was acquired through the integration of multi-channel seismic data. OBS data were processed and modeled initially using ray tracing inversion techniques. Results indicate that crustal thickness under the continental slope decreases from 21 to 11 km, crustal thickness of the northwestern sub-basin is 7.7 km, and the depth to the Moho ascends from 21 km under the upper continental slope to 11 km under the middle basin. The crust of the northwestern sub-basin is similar to that of the eastern sub-basin in its oceanic crustal structure. This structure has a thicker layer 1 (sedimentary layer) and a thinner layer 2. These characteristics are especially clear in the eastern sub-basin, which differs somewhat from typical oceanic crust. The tectonic geometry and velocity structure of the northwestern sub-basin and its margins comprise a symmetrical conjugate and indicate a pure shear mode with regard to the continental margin rifting mechanism. We did not find clear seismic signals from high velocity layers under the lower crust of the continental margin in the northern part of the northwestern sub-basin, which provides new evidence for the idea that the western part of the northern continental margin of the South China Sea constitutes nonvolcanic crust. Because the seafloor spreading period of the northwestern sub-basin was short, layer 2 might have experienced asymmetrical basalt magma flows, which may have blurred the magnetic anomaly lineations of the northwestern sub-basin.

On the geo-basis of river regulation in the lower reaches of the Yellow River

This paper investigates the important scientific problem of river regulation strategies in the lower reaches of the Yellow River, and discusses the "geo-basis" of river regulation. The concept of a geo-basis to river regulation in the lower Yellow River was discussed in terms of subsidence and sedimentation features of the fiver plain; channel features, erosion characteristics of the Loess Plateau and storm-flood features of the middle and lower reaches. The geographic features of the lower Yellow River have gradually changed since the Holocene but there has been no fundamental change. Based on an analysis of the geo-attributes of the lower reaches of the Yellow River, several conclusions on its river regulation were made. The release of sediment should be the first measure of river regulation because of deposition in the lower reaches. The fiver channels should be provided with adequate space for wandering in the lower reaches. The tail river should be also provided with necessary wandering space because of weak marine dynamics in the estuary area and changes in the delta. Because the erosion environ- ment of the Loess Plateau will not fundamentally change, river harnessing of the middle reaches should focus on improving the plateau morphology, which can be done by reducing the fragmentation of terrain and building a planation surface. Eco- remediation should focus on converting farmland to grassland. There may be extreme floods in the future, as has occurred pre- viously, thus an extreme flood defense system should be considered for the lower reaches. A periodic law for regulation in the Yellow River is discussed. We also discuss how the current use of the lower reaches of the Yellow River is unsustainable and it is urgent to research artificial rechanneling and the creation of new flow paths for the lower reaches.

Export Competition in China： Evidence from Data at Provincial Level

Through an analysis of the effects of Guangdong on exports from other provinces, this paper examines China＇s interregional relationships regarding exports. We utilize provincial level data from 1998 to 2008 and apply the system GMM to estimate an empirical model derived from the gravity equation. The results indicate that Guangdong significantly crowds out exports from other provinces. Coastal provinces are less affected than their non-coastal counterparts. In coastal areas, the displacement effect on the Yangtze River Delta is less than that on the Pan Bohai Rim. Further research reveals that the improvements in service industries, labor productivity, capital-labor ratio, and agglomeration of manufacturing industries have significantly reduced export competition. Additionally, a province with a larger market potential or a lower degree of market disintegration is less affected by Guangdong＇s export competition.