琼西南 NE向韧性剪切带构造特征及其40Ar-39Ar年代学约束

野外构造解析和显微构造分析表明,琼西南戈枕和冲卒岭两条近NE向韧性剪切带具NW向SE推覆兼NE向左旋剪切特征。采自戈枕和冲卒岭韧性剪切带内糜棱岩样品中的单矿物的40Ar-39Ar年代学研究表明,戈枕韧性剪切带04HN04样品中黑云母的40Ar-39Ar坪年龄为(227.4±0.2)Ma,冲卒岭韧性剪切带04HN24样品中的白云母给出了(229.6±0.3)Ma的坪年龄,均为印支期变形产物。上述两条剪切带的变形运动学和变形时序与华南内陆主要韧性剪切带(如雪峰山地区)具有很好的一致性,这为理解琼西南地区早中生代构造演化和华南印支块体拼合历史及其效应提供了新的信息。     

Lithostratigraphical correlation of micromammal sites and biostratigraphy of the Upper Pliocene to Lower Pleistocene in the Northeast Guadix‐Baza Basin (southern Spain)

The Plio‐Pleistocene non‐marine sequence in the northeast Guadix–Baza Basin (southern Spain) comprises alluvial and lacustrine deposits (Baza Formation). The results of a revised lithostratigraphical correlation between sections from the middle and upper members of the Baza Formation in the northeast part of the basin, supported by detailed mapping, is presented. The position of micromammal sites in the lithostratigraphical scheme, together with the results of intensive palaeontological sampling for small mammal remains, has allowed us to develop a high‐resolution biostratigraphical framework for the area. This provides an opportunity to refine the biozonation for the Plio‐Pleistocene micromammal faunas, and to define faunal events from the late Villanyian (late Pliocene) to the early Pleistocene. On the basis of the lithostratigraphical and biostratigraphical approaches we obtain the following sequence of biozones for the late Pliocene to early Pleistocene: Kislangia gusii, Mimomys cf. reidi, M. oswaldoreigi, Allophaiomys pliocaenicus and A. burgondiae. Copyright © 2000 John Wiley & Sons, Ltd.     

A 130 year record of pollution in the Suances estuary (southern Bay of Biscay): implications for environmental management

Geochemical composition (Al, Zn, Pb, Cd, Cu, Ni, Cr and As) and foraminiferal assemblages in surface and core sediments were determined to assess the current situation and the recent environmental transformation of the Suances estuary (southern Bay of Biscay, Spain). Dating of the historical record has been achieved using isotopic analysis (²¹⁰Pb, ¹³⁷Cs) and two benchmark events such as the beginning of the mineral exploitation in the Reocín Pb-Zn deposits and the evolution of the chlor-alkali industry (inputs of Hg). Concentrations of Zn, Pb and Cd in both surface and core samples are remarkably higher than background values, reflecting the existence of significant amounts of polluted materials. The dramatic environmental impact of this pollution is clearly recorded by the change of the foraminiferal assemblages that even reach an afaunal stage during recent decades. Application of two different sets of Sediment Quality Guidelines confirm that they exert potential risk to the environment, and therefore if dredged they should need specific management measures.The results provide a reference database to monitor future environmental changes in the Suances estuary, particularly as regards the contaminated sediment storage and the re-colonization by autochtonous meiofauna.     

Plankton pulses in a temperate coastal embayment during the Winter-Spring transition

Hydrographical parameters, phytoplankton productivity and plankton composition were determined over a five-month period in the Bay of Plencia, a coastal area located in the mouth of the river Butron in Biscay, Basque Country. The water column was moderately mixed during most of the study period, which lasted from February to June 1985. Nutrient levels showed high temporal variability and were affected by both river runoff and seasonal biological processes. Nutrients were present most of the time in relatively high concentrations and most of them decreased in late spring. Phytoplankton size structure analysis showed that nanoplankton had the higher chlorophyll content and was responsible for most of the primary production. The phytoplankton showed changes in community composition resulting from the normal progression of the winter-spring conditions. Short-lived peaks of diatom concentration in the spring were followed by periods of low abundance, when maxima of Cladocera and Appendicularia occurred. Total zooplankton showed two peaks of abundance in mid-winter and mid-spring, respectively. Nauplii of Copepoda, juvenile stages of Calanoida and nauplii of Cirripedia were responsible for the two peaks, together with highly seasonal groups (Cladocera, Appendicularia and Cnidaria) in the spring maxima.Primary production seems to be driven by physical processes (temperature, short photoperiod and storms) in winter, whereas depletion of nutrients and grazing by zooplankton are responsible for phytoplankton minima between peaks of abundance in the growing season. Two temporal phases were apparent when the data were analysed by a principal component analysis.     

Factors determining subsidence in urbanized floodplains: evidence from MT‐InSAR in Seville (southern Spain)

Major rivers have traditionally been linked with important human settlements throughout history. The growth of cities over recent river deposits makes necessary the use of multidisciplinary approaches to characterize the evolution of drainage networks in urbanized areas. Since under‐consolidated fluvial sediments are especially sensitive to compaction, their spatial distribution, thickness, and mechanical behavior must be studied. Here, we report on subsidence in the city of Seville (Southern Spain) between 2003 and 2010, through the analysis of the results obtained with the Multi‐Temporal InSAR (MT‐InSAR) technique. In addition, the temporal evolution of the subsidence is correlated with the rainfall, the river water column and the piezometric level. Finally, we characterize the geotechnical parameters of the fluvial sediments and calculate the theoretical settlement in the most representative sectors. Deformation maps clearly indicate that the spatial extent of subsidence is controlled by the distribution of under‐consolidated fine‐grained fluvial sediments at heights comprised in the range of river level variation. This is clearly evident at the western margin of the river and the surroundings of its tributaries, and differs from rainfall results as consequence of the anthropic regulation of the river. On the other hand, this influence is not detected at the eastern margin due to the shallow presence of coarse‐grain consolidated sediments of different terrace levels. The derived results prove valuable for implementing urban planning strategies, and the InSAR technique can therefore be considered as a complementary tool to help unravel the subsidence tendency of cities located over under‐consolidated fluvial deposits. Copyright © 2017 John Wiley & Sons, Ltd.     

东北深震与我国大陆地震活动的关系

研究了东北深震与华北、黄海和中国大陆地震活动关系,分析了中国大陆地震期幕活动的特点,认为：中国大陆第五轮回的强震活跃幕还将处这续3－5a的时间,今后几年我国大陆仍然存在发生7级以上大震的危险性,之后华北黄海的6级地震活动也将相应增强。     

银根-额济纳旗盆地航磁反映的构造特征

根据航磁资料,分析和研究银根-额济纳旗盆地的区域构造特征及其演化,同时确定了该区北东向断裂的存在,并探讨该组断裂的发生发展对区域构造的作用.     

Aptian bio-events—an integrated biostratigraphic analysis of the Almadich Formation, Inner Prebetic Domain, SE Spain

The Upper Barremian to Aptian Almadich Formation (Inner Prebetic Domain of the Betic Cordillera) is composed of hemipelagic sediments deposited on a distal carbonate ramp in the southern Iberian Palaeomargin. Within this facies we have found a thick interval of blue to black shales and marls that is interpreted as deposited under oxygen-depleted conditions. We think that this interval, dated as early Aptian, represents the local record of Ocean Anoxic Event 1a. The integrated biostratigraphic analysis of a section in the Almadich Formation, by means of planktonic foraminifera, calcareous nannofossils and ammonites, enables us to recognize most of the biostratigraphic units based on these three fossil groups and to correlate between them. The Sartousiana, Sarasini, Weissi, Deshayesi and Furcata (ammonite) Zones were identified for the Upper Barremian–Lower Aptian interval. By means of calcareous nannofossil biostratigraphy the Micrantholithus hoschulzii, Hayesites irregularis and Rhagodiscus angustus Zones, plus several additional biohorizons, were identified. A quantitative study performed on a set of 27 Lower Aptian samples has enabled the precise identification of the ‘nannoconid crisis’, the lower limit of which clearly precedes the main anoxic event, and its correlation with other bioevents. Planktonic foraminifera occur consistently throughout the Lower to Upper Aptian of the Cau section and are moderately well preserved. This fact allows us to use the most recent taxonomic framework, based on wall texture, to identify the Blowiella blowi, Schackoina cabri, Globigerinelloides ferreolensis, Globigerinelloides algerianus, Hedbergella trocoidea andTicinella bejaouaensis Zones. Coincident with the anoxic episode, the planktonic foraminiferal assemblages are composed of a significant number of forms with elongated chambers and/or tubulospines assigned to the genera Claviblowiella,Lilliputianella , Leupoldina and Schackoina. Most of the planktonic foraminiferal and nannofossil taxa are illustrated.     

Effects of preservatives on stable isotope analyses of four marine species

The aim of the present study is to quantify the effect of formalin–ethanol preservation on the carbon and nitrogen stable isotope signatures of four taxonomical groups of marine species (Himanthalia elongata, Anemonia sulcata, Mytilus galloprovincialis and Patella vulgata). To examine temporal changes in the effects of preservation and to determine if preservation induced predictable shifts in δ¹³C and δ¹⁵N signatures, repeated analyses were carried out after 6, 12 and 24 months of preservation. Data from our study showed highly variable effects of the formalin–ethanol preservation on carbon and nitrogen isotope signatures between species. The use of a general correction factor was not possible, or else it should be species-specific. Differences in nitrogen isotopic values between preserved and unpreserved samples were minor compared to the assumed enrichment between trophic levels. The combined use of data from preserved and unpreserved samples could lead to biases in the estimation of the trophic level of organisms. Changes that preservatives caused in carbon values were variable between species and not always small enough to be ignored. So the use of data from preserved samples could change the interpretation of the mixing models used to determine the importance of multiple sources of carbon. In order to elucidate the effects that preservatives have in other species, further studies will be necessary.