Seismic profiles across the middle Tan-Lu fault zone in Laizhou Bay, Bohai Sea, eastern China

The stratigraphic architecture, structure and Cenozoic tectonic evolution of the Tan-Lu fault zone in Laizhou Bay, eastern China, are analyzed based on interpretations of 31 new 2D seismic lines across Laizhou Bay. Cenozoic strata in the study area are divided into two layers separated by a prominent and widespread unconformity. The upper sedimentary layer is made up of Neogene and Quaternary fluvial and marine sediments, while the lower layer consists of Paleogene lacustrine and fluvial facies. In terms of tectonics, the sediments beneath the unconformity can be divided into four main structural units: the west depression, central uplift, east depression and Ludong uplift. The two branches of the middle Tan-Lu fault zone differ in their geometry and offset: the east branch fault is a steeply dipping S-shaped strike-slip fault that cuts acoustic basement at depths greater than 8 km, whereas the west branch fault is a relatively shallow normal fault. The Tan-Lu fault zone is the key fault in the study area, having controlled its Cenozoic evolution. Based on balanced cross-sections constructed along transverse seismic line 99.8 and longitudinal seismic line 699.0, the Cenozoic evolution of the middle Tan-Lu fault zone is divided into three stages: Paleocene-Eocene transtension, Oligocene-Early Miocene transpression and Middle Miocene to present-day stable subsidence. The reasons for the contrasting tectonic features of the two branch faults and the timing of the change from transtension to transpression are discussed. Crown Copyright (C) 2008 Published by Elsevier Ltd. All rights reserved.

Carbonate cycle and its control factors in Kuroshio source region during the last 190ka BP

Two deep sea cores (Ph05-5, 16.05 degrees N, 124.34 degrees E, water depth 3382m and WP3: 22.15 degrees N, 122.95 degrees E, water depth 2700m) retrieved from the Kuroshio source region of the western Philippine Sea were selected to carry out the CaCO3 and calcareous nannofossil faunas study. Based on AMS(14)C data and comparing tire oxygen isotope curve with SPECMAP delta O-18 (Martinson et al., 1987) a stratigraphy was established. And, combining the changes of primary productivity and dissolution index of carbonate, the carbonate cycle and its control factors were analyzed in this region during the last 190ka BP. The carbonate contents showed higher values in the glacial periods and lower values during the interglacial and Holocene periods, which characteristics was similar to the tendency of "Pacific Type" carbonate cycle. However, there were high carbonate contents in the warm period and low values during the cold interval, which displayed the same tendency with the "Atlantic Type" carbonate cycle during the last glacial period (MIS4-2) in the east of Phillipines. The variations of primary productivity and carbonate dissolution index indicated that the carbonate dissolution was a major factor controlling the carbonate content in tire cast of Philippines, and the variations in carbonate contents were mainly affected by the productivity of calcareous organism in the Southeast of Taiwan. The "Atlantic Type" carbonate cycle in the cast of Phillipines during the last glacial period (MIS4-2) was an effect of the process of dissolution combined with the change of primary productivity.

The variation of upper ocean structure and paleoproductivity in the Kuroshio source region during the last 200 kyr

A core from the source region of the Kuroshio warm current (east of the Luzon Island) was analyzed using several proxies in order to study the variability of the Western Pacific Warm Pool (WPWP) during the last two glacial-interglacial cycles. Primary productivity (PP) variations were deduced from variations in the coccolith flora. Primary productivity was higher during glacial periods (the end of Marine Isotope Stage [MIS] 3, some periods in MIS 2 and 6), and decreased during interglacial periods (MIS 7, MIS Se and probably MIS 5c-5d), with the lowest PP in MIS 5e. variations in the delta C-13 difference in benthic and bulk carbonate, thus in the vertical gradient of delta C-13 in dissolved inorganic carbon (Delta delta C-13(c). (wuellerstorfi-N. dutertrei) and Delta delta C-13(c.) (wuellerstorfi-coccolith)) Coincided With the PP Changes, showing that export productivity was low during interglacial periods (MIS 7, MIS 5e and Holocene) and high during glacial periods (MIS 6, probably MIS 5c-5d, late MIS 4 and late MIS 3). Comparison of foraminiferal carbonate dissolution indicators and PP changes reveals that nannofossil assemblage in core Ph05-5 is not sensitive to carbonate dissolution intensity. The depth of the thermocline (DOT) was estimated from planktonic forminiferal assemblages, and was relatively greater during interglacial periods (MIS 7, MIS 5e, probably MIS 5c and Holocene) than during glacials (middle MIS 6, probably MIS 5b and 5d, some periods in MIS 4, MIS 3 and MIS 2). Good coherence between the paleoproductivity records and the DOT suggests that the DOT changes could be the primary control factor in changes of paleoproductivity, and the glacial high productivity in the Kuroshio source region could be associated with a global increase of nutrient concentration in the intermediate waters that upwelled into the photic zone. The low CO2 values derived for intervals of high productivity and a relatively shallow DOT suggest that the changes in biological productivity and DOT in the equatorial Pacific could have modified atmospheric CO2 concentrations. High Sea Surface Temperatures (SSTs) during the warm MIS 5e in combination with intensified monsoonal rain fall could have resulted in a more intense stratification of the upper waters, resulting in low nutrient supply to the surface waters and a resulting decrease in productivity. (C) 2010 Elsevier B.V. All rights reserved.

Improvement of different source function expressions in SWAN model for the Bohai Sea

The simulating wave nearshore (SWAN) wave model has been widely used in coastal areas, lakes and estuaries. However, we found a poor agreement between modeling results and measurements in analyzing the chosen four typical cases when we used the default parameters of the source function formulas of the SWAN to make wave simulation for the Bohai Sea. Also, it was found that at the same wind process the simulated results of two wind generation expressions (Komen, Janssen) demonstrated a large difference. Further study showed that the proportionality coefficient alpha in linear growth term of wave growth source function plays an unperceived role in the process of wave development. Based on experiments and analysis, we thought that the coefficient alpha should change rather than be a constant. Therefore, the coefficient alpha changing with the variation of friction velocity U (*) was introduced into the linear growth term of wave growth source function. Four weather processes were adopted to validate the improvement in the linear growth term. The results from the improved coefficient alpha agree much better with the measurements than those from the default constant coefficient alpha. Furthermore, the large differences of results between Komen wind generation expression and Janssen wind generation expression were eliminated. We also experimented with the four weather processes to test the new white-capping mechanisms based on the cumulative steepness method. It was found that the parameters of the new white-capping mechanisms are not suitable for the Bohai Sea, but Alkyon's white-capping mechanisms can be applicable to the Bohai Sea after amendments, demonstrating that this improvement of parameter alpha can improve the simulated results of the Bohai Sea.

渤海湾盆地济阳坳陷东部走滑构造特征及其对油气成藏的影响研究

研究区位于郯庐断裂中段与济阳坳陷的构造结合部，区内走滑构造广泛发育，主要的走滑断裂有7条，分别是郯庐断裂带的东西两支、垦东断层、孤东断层、长堤断层、埕东断层和发育于垦东凸起中部的浅层走滑构造带。走滑构造带与油气富集带有着明显的对应关系。 通过对研究区内二维、三维地震测线和平面构造图的精细解释和分析，分别揭示了各走滑断裂在平面、剖面和三维空间上的构造形态。根据走滑断裂及其伴生构造的平面和剖面上的几何学特征，将研究区内的走滑断裂划分为三种类型：成熟型走滑断裂、隐伏型走滑断裂、不连续型的走滑断裂。 从理论模式研究入手，推导了拉分盆地中盆地的走滑速率与沉降速率之间的关系，证实了走滑速率同盆地的几何形状参数、最大沉降深度和盆地的沉降速率存在着稳定的数值关系。通过对莱州湾地区潍北凹陷基底沉降历史的分析，建立了潍北凹陷沉降速率与郯庐断裂中段走滑速率之间的经验关系式，进而求出郯庐断裂中段新生代右行走滑位移量的大小为40km。 运用2DMove软件，对研究区内四条典型剖面进行构造复原，计算出了各条剖面每个时期的伸展参数，对研究区构造活动强度进行了定量分析，揭示了研究区的构造演化规律。通过运用Ansys软件进行有限元模拟，恢复了晚白垩世晚期-古近纪早期研究区内的构造应力场和应变场，揭示了扭张作用是研究区内走滑断层开始走滑的主要原因。 通过上述分析，结合对究区内近几年勘探开发成功和失败的实例分析，全面探讨了走滑活动对于油气成藏“生”、“储”、“盖”、“圈”、“运”、“保”各因素的影响。

Organic carbon source and burial during the past one hundred years in Jiaozhou Bay, North China

Organic carbon (OC), total nitrogen (TN), and Pb-210 in core sediment were measured to quantify the burial of organic carbon and the relative importance of allochthonous and autochthonous contributions during the past one hundred years in Jiaozhou Bay, North China. The core sediment was dated using Pb-210 chronology, which is the most promising method for estimation of sedimentation rate on a time scale of 100-150 years. The variation of the burial flux of organic carbon in the past one hundred years can be divided into the following three stages: (1) relatively steady before 1980s; (2) increasing rapidly from the 1980s to a peak in the 1990s, and (3) decreasing from the 1990s to the present. The change is consistent with the amount of solid waste and sewage emptied into the bay. The OC:TN ratio was used to evaluate the source of organic carbon in the Jiaozhou Bay sediment. In the inner bay and bay mouth, the organic carbon was the main contributor from terrestrial sources, whereas only about half of organic carbon was contributed from terrestrial source in the outer bay. In the inner bay, the terrestrial source of organic carbon showed a steady change with an increase in the range of 69%-77% before 1990 to 93% in 2000, and then decreased from 2000 because of the decrease in the terrestrial input. In the bay mouth, the percentage of organic carbon from land reached the highest value with 94% in 1994. In the outer bay, the sediment source maintained steady for the past one hundred years.

Role of the Jiaozhon Bay as a source/sink of CO2 over a seasonal cycle

The seasonal evolution of dissolved inorganic carbon (DIC) and CO2 air-sea fluxes in the Jiaozhou Bay was investigated by means of a data set from four cruises covering a seasonal cycle during 2003 and 2004. The results revealed that DIC had no obvious seasonal variation, with an average concentration of 2035 mu mol kg(-1) C in surface water. However, the sea surface partial pressure of CO2 changed with the season. pCO(2) was 695 mu atm in July and 317 mu atm in February. Using the gas exchange coefficient calculated with Wanninkhof's model, it was concluded that the Jiaozhou Bay was a source of atmospheric CO, in spring, summer, and autumn, whereas it was a sink in winter. The Jiaozhou Bay released 2.60 x 10(11) mmol C to the atmosphere in spring, 6.18 x 10(11) mmol C in summer, and 3.01 x 10(11) mmol C in autumn, whereas it absorbed 5.32 x 10(10) mmol C from the atmosphere in winter. A total of 1.13 x 10(11) mmol C was released to the atmosphere over one year. The behaviour as a carbon source/sink obviously varied in the different regions of the Jiaozhou Bay. In February, the inner bay was a carbon sink, while the bay mouth and the Outer bay were carbon sources. In June and July, the inner and Outer bay were carbon sources, but the strength was different, increasing from the inner to the outer bay. In November, the inner bay was a carbon source, but the bay Mouth was a carbon sink. The outer bay was a weaker CO2 Source. These changes are controlled by many factors, the most important being temperature and phytoplankton. Water temperature in particular was the main factor controlling the carbon dioxide system and the behaviour of the Jiaozhou Bay as a carbon source/sink. The Jiaozhou Bay is a carbon dioxide source when the water temperature is higher than 6.6 degrees C. Otherwise, it is a carbon sink. Phytoplankton is another controlling factor that may play an important role in behaviour as a carbon source or sink in regions where the source or sink nature is weaker.

The distribution, enrichment and source of potential harmful elements in surface sediments of Bohai Bay, North China

A geochemical study of Bohai Bay surface sediments was carried out to analyze the potential harmful element (PHE: Ge, Mo, In, Sn, Sb,Te, Tl, Bi and V) concentrations, transportation and deposition, enrichment factors and sources. Germanium, Mo, In, Sn, Sb, Te, Tl, Bi and V concentrations in the surface sediments were: 1.43-1.71, 0.52-1.43, 0.04-0.12, 2.77-4.14, 1.14-2.29, 0.027-0.085, 0.506-0.770, 0.27-0.63 and 70.35-115.90 mu g/g, respectively. The distributions of total PHE concentrations, together with sequential extraction analyses, showed that the PHEs were mainly due to natural inputs from the continental weathering delivered to the bay by rivers and atmospheric transportation and deposition. However, high Mo, Sb, Te, Bi and V occurred in non-residual fractions, suggesting some anthropogenic inputs in addition to the natural inputs. Besides sources, the distributions of PHEs were influenced by the coupling of physical, chemical and biological processes. Enrichment factor (EF) was computed for each site for each element in order to assess the polluting elements and the degree of pollution at each site. Results revealed that the EFs were generally lower than 1.0, particularly for Ge, Mo, In, Sn, Tl and V; however, the EFs were higher (>1.5), particularly for Sb, Te and Bi, revealing moderate contamination. (C) 2010 Elsevier B.V. All rights reserved.

Effects of nitrogen source and concentration on growth rate and fatty acid composition of Ellipsoidion sp (Eustigmatophyta)

In order to study the effects of different nitrogen source and concentration on the growth rate and fatty acid composition, a marine microalga Ellipsoidion sp. with a high content of eicosapentaenoic acid (EPA) was cultured in media with different nitrogen sources and concentrations. During the pre-logarithmic phase, the alga grew faster with ammonium as N source than with nitrate, but the reverse applied during the post-logarithmic phase. The alga grew poorly in N-free medium or medium with urea as the sole N source. In the same growth phase, ammonium medium resulted in higher yield of total lipid, but the EPA yield did not differ significantly different from that using nitrate medium. The maximum growth rate occurred in medium containing 1.28 mmol L-1 sodium nitrate, while maximum EPA and total lipid contents were reached at 1.92 mmol L-1, when EPA accounted for 27.9% total fatty acids. The growth rate kept stable when NH4Cl ranged from 0.64 to 2.56 mmol L-1, and the maximum content of total lipid and EPA occurred in the medium with 2.56 mmol L-1 NH4Cl. The EPA content was higher in the pre- than post-logarithmic phase, though the total lipid content was lower. The highest EPA content expressed as percent total fatty acid was 27.9% in nitrate medium and and 39.0% in ammonium medium.

Berberine as a natural source inhibitor for mild steel in 1 M H2SO4

Berberine was abstracted from coptis chinensis and its inhibition efficiency on corrosion of mild steel in 1 M H2SO4 was investigated through weight loss experiment, electrochemical techniques and scanning electronic microscope (SEM) with energy disperse spectrometer (EDS). The weight loss results showed that berbefine is an excellent corrosion inhibitor for mild steel immersed in 1M H2SO4. Potentiodynamic curves suggested that berbefine suppressed both cathodic and anodic processes for its concentrations higher than 1.0 x 10(-4) M and mainly cathodic reaction was suppressed for lower concentrations. The Nyquist diagrams of impedance for mild steel in 1 M H2SO4 containing berbefine with different concentrations showed one capacitive loop, and the polarization resistance increased with the inhibitor concentration rising. A good fit to Flory-Huggins isotherm was obtained between surface coverage degree and inhibitor concentration. The surface morphology and EDS analysis for mild steel specimens in sulfuric acid in the absence and presence of the inhibitor also proved the results obtained by the weight loss and electrochemical experiments. The correlation of inhibition effect and molecular structure of berberine was then discussed by quantum chemistry study. (c) 2005 Elsevier B.V. All rights reserved.

Stable Carbon Isotopic Composition in Soil Organic Carbon and C3/C4 Source Variations at the Haibei Alpine Meadow

Stable carbon isotopes of organic matter originated from different soil layers (0～5 cm, 5～15 cm, 15～25 cm, 25～35 cm, 35～50 cm, 50～65 cm) were investigated in the Haibei Alpine Meadow Ecosystem Research Station of the Chinese Academy of Sciences. The preliminary results indicated that δ13C values of soil organic matter increased with increased soil depth. δ13C of soil organic carbon in 0～5 cm layer showed the lowest value, -25.09‰; while 50～65 cm soil layer possessed the lowerδ13C value, -13.87‰. Based on mass balance model of stable isotopes, it was proposed that the percentage of C4 carbon source tend to increase with increased soil depth. The preliminary study indicated that alpine meadow might have undergone a successive process from C4-dominated community to C3-dominated one. However, changing δ13C values in atmospheric CO2 overtime and different processes of soil organic carbon formation (or eluviation) might somewhat contribute to increasing δ13C values. In this case, mass balance model would underestimate C3 community and overestimate C4 community.

天山南北山前盆地中-新生代沉积记录及其动力学分析

It has been long known that intense multiple Mesozoic-Cenozoic intracontinental deformations have controlled the grand scale basin-range structural evolution of the Tianshan and its adjacent basins. So it is important to study the sedimentary records of the piedmont basins along the two sides of the Tianshan synthetically for the continental geodynamic research.We carried out a magnetostratigraphy study on Cretaceous- Tertiary succession and U-Pb dating analysis of detrital zircons from the representative sandstone samples of the Mesozoic-Cenozoic deposits in Kuqa Subbasin, northern Tarim Basin, combining our previous results of multiple depositional records from different profiles including paleocurrent data, conglomerate clast, sandstone framswork grains, detrital heavy minerals and geochemistry analysis, so the multiple intracontinental tectonic processes of Tianshan and their depositional response in the Kuqa Subbasin can be revealed. The results show that the tectonic evolution of the Tianshan Orogen and the sedimentary processes of the Kuqa Subbasin can be divided into four periods: early Triassic(active period), from middle Triassic to late Jurassic(placid period), from early Cretaceous to Tertiary Paleocene(active period) and from Neogene to present (intensely active period). Simultaneously，the depositional records reveal the provenance types and tectonic attributes in different periods. As follows, the lower Triassic with a dominant age ranging from 250 to 290Ma of the Zircons, which were principally derived from alkali feldspar granites and alkaline intrusion obviously, relative to the magma activity in Permian. In middle Triassic-late Jurassic, the two samples collected from the Taliqike formation and the Qiakemake formation respectively show the age peak at 350～450Ma, which was relative to the subduction of the Tarim Block to Yili-Central Tianshan Plate. In this period the provenance of the Kuqa deposits was the Central Tianshan arc orogenic belts distantly with little height predominance.During early Cretaceous-Paleogene, two major zircons age spectra at 240~330Ma and 370~480Ma have been acquired, with some other not dominant age ranges, indicating complicated provenance types. In Neogene, the detrital zircons age dating ranges from 460 to 390 Ma primarily. What’s more, the newer chronology of the stratigraphy and the older source age, indicating that Tianshan was uplifted and exhumated further strongly. Further study on the heavy mineral and the detrital zircons age dating of the Mesozoic-Paleogene representative profiles in southern Junggar Basin, combined with the published results of the sandstone framework grains, we consider that it occurred obvious sedimentary and tectonic changes occurred in the inside of Jurassic, from late Jurassic to early Cretaceous and form early Cretaceous to late Cretaceous. On this faces, there are remarkable changes of the steady minerals and unstable minerals, the sandstone maturity and the age spectra of the detrital zircons. Compared the sedimentary records from the two sides of the Tianshan, We find that they are different obviously since Middle Jurassic. It can be concluded that Tianshan have uplifted highly enough to influence the paleo-climatic. According to the current strata division, the structural activity apparently showed a migration from north to south. That is to say, the South Tianshan uplift later than the north, especially from late Jurassic to early Cretaceous , but it was uplifted and exhumated more strongly. Furthermore, correlating the depositional records and tectonic styles in the Kuqa-South Tianshan basin-range conjugation site in the east with the west, the obvious differentiation between the west and the east from the Cretaceous especially in Tertiary along the Tianshan-Kuqa belt was revealed, probably showing earlier uplifting in the east while greater exhumation depth and sediment rates in the west. In addition, the contacting style of Kuqa subbasin to the Tianshan Orogenic belts and the basement structure are also inconsistent at different basin-range conjugation sites. It is probably controlled by a series of N-S strike adjusting belts within the Kuqa subbasin, or probably correlated with the material difference at the complicated basin-range boundary. The research on the Mesozoic-Cenozoic tectonic-depositional response in the piedmont basins along the two sides of the Tianshan shows that the basin-filling process was controlled by the intracontinental multicyclic basin-range interactions, especially affected by the intense tectonic differentiations of basin-range system, which can’t be illuminated using a single evolutionary model.