Cretaceous Oceanic Red Beds: Distribution, Lithostratigraphy and Paleoenvironments

Cretaceous oceanic red beds (CORBs) represented by red shales and marls, were deposited during the Cretaceous and early Paleocene, predominantly in the Tethyan realm, in lower slope and abyssal basin environments. Detailed studies of CORBs are rare; therefore, we compiled CORBs data from deep sea ocean drilling cores and outcrops of Cretaceous rocks subaerially exposed in southern Europe, northwestern Germany, Asia and New Zealand. In the Tethyan realm, CORBs mainly consist of reddish or pink shales, limestones and marlstones. By contrast, marlstones and chalks are rare in deep-ocean drilling cores. Upper Cretaceous marine sediments in cores from the Atlantic Ocean are predominantly various shades of brown, reddish brown, yellowish brown and pale brown in color. A few red, pink, yellow and orange Cretaceous sediments are also present. The commonest age of CORBs is early Campanian to Maastrichtian, with the onset mostly of oxic deposition often after Oceanic Anoxic Events (OAEs), during the early Aptian, late Albian-early Turonian and Campanian. This suggests an indicated and previously not recognized relationship between OAEs, black shales deposition and CORBs. CORBs even though globally distributed, are most common in the North Atlantic and Tethyan realms, in low to mid latitudes of the northern hemisphere; in the South Atlantic and Indian Ocean in the mid to high latitudes of the southern hemisphere; and are less frequent in the central Pacific Ocean. Their widespread occurrence during the late Cretaceous might have been the result of establishing a connection for deep oceanic current circulation between the Pacific and the evolving connection between South and North Atlantic and changes in oceanic basins ventilation.     

深海锰结核—核形石的新类型

对东太平洋深海锰结核用偏光显微镜、扫描电镜和透射电镜进行了研究。结果表明其由核心和叠层石包壳组成,具有核形石特有的结构和构造。因此,深海锰结核是一种锰质核形石。根据包壳中叠层石的种类,东太平洋锰质核形石可分为两种类型:一种表面光滑,内部致密,包壳主要由微小叠层石组成;另一种表面呈瘤状,内部疏松,包壳主要由奇异叠层石组成。透射电镜研究表明,锰质核形石的建造者是纳米级超微生物。其中微小叠层石(Minima)是由中华微放线菌(Miniactinomyces chinensis sp.nov.)建造的;奇异叠层石(Admirabilis)是由太平洋螺球孢菌(Spirisosphaerospora pacifica sp.nov.)建造的。     

Pelagic Nitrogen Cycling in Jiaozhou Bay, a Model Study I： the Conceptual Model

A zero-dimensional box model (PNCMjzb) with six state variables (ammonium, nitrate, dissolved organic nitrogen, phytoplankton, zooplankton and detritus) was developed to study nitrogen cycling in the Jiaozhou Bay pelagic ecosystem. The dominant processes within these compartments are considered with nitrogen as flow currency. Phytoplankton and zooplankton are treated as separate state variables, assuming that the species composition was dominated by two or three species the dynamic constants of which are similar and that they represent the entire plankton community. The microbial loop has not been integrated explicitly in the model. The turnover of bacteria is included implicitly in processes such as detritus decomposition, DON remineralization, pelagic nitrification and denitrification. The model is driven by two forcing variables, viz. water temperature and light intensity. Historical data from the1980s and 1990s were compiled and used for model calibration. In this paper (part Ⅰ), the consideration of every main compartment in the model is interpreted in detail. And the applied equations and parameters are presented. The main results from the simulations together with discussion about phytoplankton dynamics and primary production in Jiaozhou Bay are presented in the next paper (part Ⅱ).     

Scaeurgus unicirrhus (Orbigny, 1840) (Cephalopoda,Octopodidae): first record from the South-East Atlantic

The first recorded specimens of Scaeurgus unicirrhus from the South-East Atlantic are described. Five males and two females were captured on the Valdivia Bank, Walvis Ridge, between 24 and 27°S, 400 miles off the Namibian coast. They are compared with specimens caught from other areas, and historical and geographic surveys of the species are made.     

St Helena Bay (southern Benguela) then and now: muted climate signals,large human impact

The development of suitable reference states for ecosystem-based management requires documentation of changes in structure and functioning of marine ecosystems, including assessment of the relative importance of bottom-up and top-down processes as drivers of change. We used monitoring data available from St Helena Bay, the most productive bay and an important nursery area situated on the west coast of South Africa, during 1950–2010 to reveal changes in the abiotic and biotic components. St Helena Bay in the 1950s showed similarities to 2000–2010 in terms of wind patterns, hydrology and phytoplankton. Upwelling, oxygen and nutrient concentrations in subthermocline water displayed pronounced decadal-scale variability. Primary production in St Helena Bay is variable, but consistently higher than that on the adjacent Namaqua shelf. Zooplankton size composition and biomass in August have changed markedly since the 1950s. During 2001–2010, mesozooplankton biomass in autumn was considerably lower than in summer, probably due to predation by small pelagic fish. Pelagic fish catch patterns and distributions have altered dramatically. Conservation measures, implemented to reverse past negative human impact, have benefitted marine mammals, the abundance of which has increased in the area, but additional conservation measures are necessary to reverse the decline in African penguins Spheniscus demersus. St Helena Bay shows a muted response to long-term change in the southern Benguela, with marked decadal variability but no clear long-term trend in oceanography and biogeochemistry. Changes in ecosystem boundary conditions and fishing pressure cannot be ignored as important drivers of change in the southern Benguela since the 1950s.     

Surviving off junk: low-energy prey dominates the diet of African penguins Spheniscus demersus at Mercury Island,Namibia, between 1996 and 2009

The diet of African penguins Spheniscus demersus in Namibia consisted mainly of sardine Sardinops sagax in the 1950s. Since the collapse of pelagic fish stocks in the 1970s, birds fed mainly on bearded (pelagic) goby Sufflogobius bibarbatus, a low-energy prey species. We present diet data for African penguins breeding at Mercury Island, the largest colony for this species in Namibia, between 1996 and 2009. Bearded goby was the main prey item throughout the study period, both in terms of frequency of occurrence (67.8%; SD 31.2) and in terms of mass (59.2%; SD 31.5). Diet composition varied throughout the year as well as between years; birds occasionally fed on a variety of fish species other than bearded goby. In Namibia, poor prey abundance is considered as a major factor contributing to the decline of penguin numbers after the collapse of the sardine stocks. However, bearded goby appears to be relatively abundant along Namibia's southern coast and low prey quality rather than low abundance appears to be a key factor influencing population dynamics of African penguins and other marine top predators in southern Namibia.     

Evolution of Cambrian to Ordovician trace fossils in pelagic deep-sea chert,Australia

Cambrian to Ordovician pelagic radiolarian cherts in the Lachlan Fold Belt in southeastern Australia contain trace fossils demonstrating the faunal diversification that occurred during the Ordovician on the deep-sea floor. The Cambro-Ordovician Howqua Chert has a very low degree of bioturbation, and the trace fossils are small and shallow. In contrast, the late Middle to Late Ordovician cherts are strongly bioturbated with larger, deeper burrows, and contain more morphologically diverse trace fossils. This records a substantial increase in the size, abundance and activity of deep-ocean benthic animals living on the floor of the ocean bordering Australia.     

Curie Temperature Analyses of Upper Jurassic and Lower Cretaceous Pelagic Limestones

Summary. Magnetic extracts were prepared from samples of Upper Jurassic and Lower Cretaceous pelagic limestones from France and Spain. Thermomagnetic analysis of the magnetic extracts using a microbalance required careful monitoring of base weight changes during heating. Heating in argon gas atmosphere induced production of magnetite during heating while slight oxidation occurred during heating in air. the dominant Curie temperature detected by the thermomagnetic analyses was the 585°C Curie temperature of magnetite. the 680°C Curie temperature of haematite was only detected when isothermal remanent magnetism (IRM) data indicated large concentrations of haematite. Even when IRM data indicated its presence, the thermomagnetic analyses did not detect the Neel temperature of goethite. Although thermomagnetic analyses of magnetic extracts provide more direct identification of the dominant, strongly ferromagnetic minerals, IRM acquisition and subsequent thermal demagnetization is a superior technique in detecting high coercivity, weakly ferromagnetic minerals such as goethite and haematite.     

东经90°海岭的远洋沉积记录与晚新生代重大构造-环境事件

东经 90°海岭的北部远洋型沉积记录是青藏高原隆升的远程监视器。文章应用有孔虫组合分析和壳体微量元素分析 ,结合相关的沉积学、地球化学、古地磁学和微体古生物学工作 ,对以ODP75 8钻孔为代表的 9Ma以来的沉积记录综合研讨 ,识别出对应于高原阶段隆升 (3 7～ 3 2Ma、0 .8～ 0 .6Ma、0 .17～ 0 .16Ma)的重大环境变化信号。文章还提出印度冬季季风强度是反映高原构造活动关键标志的观点。按照这种观点 ,海岭远洋记录提供的晚新生代最大环境转折时段位于 3.7～ 3.2Ma间。