The Lower Cretaceous succession of the northwestern Barents Shelf: Onshore and offshore correlations     

《Marine and Petroleum Geology》2017

The Lower Cretaceous succession in the Barents Sea is listed as a potential play model by the Norwegian Petroleum Directorate. Reservoirs may occur in deep to shallow marine clastic wedges located in proximity to palaeo-highs and along basin margins. In addition, shelf-prism-scale clinoforms with high amplitude anomalies in their top- and bottomsets have been reported from reflection seismic but they have never been drilled. In Svalbard, the exposed northwestern corner of the Barents Shelf, Lower Cretaceous strata of shelfal to paralic origin occur, and includes the Rurikfjellet (Valanginian–Hauterivian/lowermost Barremian), Helvetiafjellet (lower Barremian–lower Aptian) and Carolinefjellet formations (lower Aptian–middle Albian). By combining sedimentological outcrop studies and dinocyst analyses with offshore seismic and well ties, this study investigate the link between the onshore strata and the offshore clinoforms. Age-vise, only three (S1–S3) of the seismic sequences defined in the offshore areas correlate to the onshore strata; S1 correspond to the Rurikfjellet Formation, S2 to the Helvetiafjellet Formation and the lower Carolinefjellet Formation, and S3 to the upper Carolinefjellet Formation. Offshore, all three sequences contain generally southward prograding shelf-prism-scale clinoforms. A lower Barremian subaerial unconformity defines the base of the Helvetiafjellet Formation, and its extent indicates that most of the Svalbard platform was exposed and acted as a bypass zone in the early Barremian. Onshore palaeo-current directions is generally towards the SE, roughly consistent with the clinoform accretion-direction towards the S. The local occurrence of a 150 m thick succession of gravity flow deposits transitionally overlain by prodelta slope to delta front deposits in the Rurikfjellet Formation, may indicate that shelf-edges also developed in Svalbard. The late Hauterivian age of theses deposits potentially highlights the inferred offlapping nature of the Lower Cretaceous strata as they predate the lower Barremian unconformity, and thus record a hitherto unknown regression in Svalbard. The presence of the lower Barremian subaerial unconformity in Svalbard, the general southeastward palaeo-current directions, and the age-equivalent clinoform-packages south of Svalbard, suggests that the onshore and offshore strata is genetically linked and was part of the same palaeo-drainage system.  相似文献   

A new biostratigraphic correlation for Late Cretaceous–Paleocene strata of the Gulf of Guinea: Evidence from dinoflagellate cysts     

Raquel Sánchez-Pellicer  Edwige Masure  Loïc Villier 《Comptes Rendus Geoscience》2017,349(1):32-41

A new biostratigraphic correlation for Late Cretaceous and Palaeocene strata of the Côte d’Ivoire–Ghana continental margin has been developed from the identification of significant dinoflagellate cyst events in ODP Hole 959D. The Late Cretaceous stage boundaries are mostly consistent with previous studies. However, the Maastrichtian/Danian boundary is placed much lower than previously recognized on the basis of the first occurrences of Carpatella cornuta and Damassadinium californicum. The base of the Selandian is recognized from the last occurrence of Cerodinium diebelii and the first occurrence of Adnatosphaeridium multispinosum. The base of the Thanetian is recognized from the first occurrence of Areoligera gippingensis. The rarity of the age-marker taxa is the main reason for different age determinations among studies of the same section.  相似文献   

Occurrence of PSP-producing dinoflagellate Alexandrium tamiyavanichii in Bingo-Nada, the central coastal water of the Seto Inland Sea, Hiroshima Prefecture, Japan     

Beppu R  Nojima K  Tsuruda S  Gomez-Delan G  Barte-Quilantang M  Taniyama S  Sagara T  Nishio S  Takayama H  Miyazawa K  Asakawa M 《Marine pollution bulletin》2008,56(4):758-763

During surveillance of the distribution of the paralytic shellfish poison (PSP)-producing dinoflagellate in 2003, 2004 and 2005 along the coastlines of the Seto Inland Sea, Hiroshima Prefecture, Japan, some species of toxic phytoplankton were isolated from the eastern coasts, Bingo-Nada, the central regions of the Seto Inland Sea. It was rather unexpectedly revealed from the basis of the morphological characteristics that they were unambiguously identified as Alexandrium tamiyavanichii and Alexandrium catenella. Two strains (ATY041106, ATY051018) of A. tamiyavanichii showed a specific toxicity of 38.7 x 10(-6) and 111.5 x 10(-6)MU/cell, respectively. These values seemed to be several times or much higher than that of A. catenella (AC030816, AC040614), having a specific toxicity of 4.5 x 10(-6) and 4.1 x 10(-6)MU/cell, respectively, isolated in the same area. From the results of HPLC-furuorometric analysis, it revealed that the toxins in ATY041106 exist almost exclusively as beta-epimers (C2, GTX3, GTX4), which accounted for 72.7 mol%. The toxin profiles of this strain are featured by the presence of a large amount of GTX3 (59.1 mol%) and a small amount (20.6%) of C1 and 2 in comparison with the PSP compositions of A. tamarense, which is isolated as the main responsible species in Hiroshima Bay, a western part of coastal sea in Hiroshima Prefecture. On the other hand, it revealed that the toxin profiles of two strains (AC030816, AC040614) of A. catenella exist almost exclusively as beta-epimers (C2, GTX3, GTX4), which accounted for 81.8 and 56.5 mol%, as the same manner. The toxin profiles of these two strains are featured by the presence of a large amount of C2 (80.5 and 46.3 mol%) in comparison with the PSP compositions of A. tamiyavanichii. To our knowledge, this is the first record to show the distribution and harmful influence of A. tamiyavanichii and A. catenella in Bingo-Nada in Hiroshima Prefecture. Though contamination of bivalves with these PSP-producing planktons in this area has not occurred yet so far, attention should be paid to this species as well as the other causative dinoflagellate from the stand point of public health and food hygiene.  相似文献   

长江口甲藻孢囊的初步研究   总被引：13，自引：2，他引：11  

顾海峰  方琦  李瑞香  蓝东兆  朱明远 《海洋与湖沼》2004,35(5):413-423

休眠孢囊在甲藻生活史中扮演着重要的角色 ,它们可以在沉积物中保留很长一段时间 ,因此能够提供水体中浮游植物多样性的综合记录。作者选择了长江口孢囊种类最多的一个站位 ( 1 2 2° 30 .64′E ,2 9° 0 .0 1′N) ,在 2 0 0 2年 1 1月、2 0 0 3年 2月和 5月采集了 3次样品 ,首次通过萌发试验对长江口沉积物中的甲藻孢囊进行了研究 ,根据孢囊和藻类的形态学特征鉴定了其中的 2 8种。这 2 8种孢囊均出现在 2 0 0 2年 1 1月的样品中 ,2 0 0 3年 2月和 5月的样品中分别发现了 5种和 1 7种。 9种甲藻孢囊在中国沿海首次被记录 ,它们是Alexandriumsp .,Scrippsiellaramonii,S .sp .1 ,Protoperidiniumsp .1 ,P .sp .2 ,P .sp .3,Diplopsalopsisorbicu laris,Diplopsalislebourae,Gyrodiniumsp .,并发现了A .tamarense,A .catenella和Lingulo diniumpolyedra等 3种有毒甲藻的孢囊。Protoperidiniumspp .中除了P .americanum萌发孔都是六角形的 ,而作者记录的P .sp .3萌发孔是裂开状 ,是一个特殊的现象。S .trochoidea和A .tamarense是研究站位的优势种 ,在 2 0 0 2年 1 1月的样品中分别占到 2 9.5 %和 1 1 .4%。长江口A .tamarense孢囊的丰度由于萌发可能被低估。孢囊的密度与其它海区相比较大 ,部分反映了该  相似文献   

Distribution and characterization of Chilean populations of the brine shrimp Artemia (Crustacea, Branchiopoda, Anostraca)     

Oscar Zuñiga  Rodolfo Wilson  Francisco Amat  Francisco Hontoria 《International Journal of Salt Lake Research》1999,8(1):23-40

Hypersaline habitats in Chile, from marine solar salt pans to saline lagoons and pools in Andean salars, were prospected in search of Artemia populations. These saline ecosystems were characterized through physico-chemical parameters and ionic composition of their brines. Biometrics of cysts and nauplii, as well as morphometrics by using multivariate discriminant analysis for adult specimens evidenced that the Chilean populations of brine shrimp belong to A. franciscana. Cross-breeding results supported the former hypothesis of conspecific Chilean populations, and their differences with A. persimilis, also endemic to the New World, but restricted to Argentinean sites.  相似文献   

1998年春季珠江口海域大规模赤潮原因生物的形态分类和生物学特征I   总被引：9，自引：4，他引：5  

黄长江  董巧香 《海洋与湖沼》2000,31(2):197-204

对１９９８年４月１５日采集于广东珠江口万山群岛桂山岛网箱养殖区的赤潮活体水样 和福尔马林固定样品进行优势种的形态分类和生物学特征的研究。结果发现,三宅裸甲藻 （Ｇｙｍｎｏｄｉｎｉｕｍ ｍｉｋｉｍｏｔｏｉ）是此次赤潮的最优势种,最高密度达到 ７．６ × １０６ｃｅｌｌｓ／Ｌ。另两种优 势种为斯氏多沟藻（Ｐｏｌｙｋｒｉｋｏｓ　ｓｃｈｗａｒｔｚｉｉ）和螺旋螺沟藻（Ｇｙｒｏｄｉｎｉｕｍ ｓｐｉｒａｌｅ）,其最高密度分 别达到 １．１× １０５ｃｅｌｌｓ／Ｌ和 １０４－１０５ｃｅｌｌｓ／Ｌ。此次赤潮的原因生物都属于裸甲藻类,死后或用 福尔马林固定后细胞要么立即裂解,要么变形缩小。有些种类如螺旋螺沟藻在固定样品中找 不到其踪迹,因而无法精确计数。本文描述的３种赤潮藻在细胞、色素体、核、上锥沟和链状群 体等形态构造及外观上与国外学者所描述的几乎完全一致,只是细胞比日本海域产的稍小。 这可能与珠江口海域纬度较日本低有关。电镜照片显示三宅裸甲藻有一明显的上锥沟,斯氏 多沟藻则营养细胞和孢囊同时存在。  相似文献   

Diversity and geographical distribution of resting stages of eukaryotic algae in the surface sediments from the southern Chinese coastline based on metabarcoding partial 18S rDNA sequences     

Lei Liu  Zhaohui Wang  Songhui Lu 《Marine Ecology》2020,41(3):1-17

Surface sediment samples were collected from sixteen sites of the southern Chinese coastline in this study. Diversity of eukaryotic microalgae was examined using high-throughput sequencing of 18S rDNA to understand the community structure and geological distribution of microalgal resting stages. A total of 218 operational taxonomic units (OTUs) were detected for eukaryotic algae, and only 75 OTUs (34.40%) were detected into species level. The algal communities were composed of sixty-four genera belonged to twelve classes of four phyla. Dinoflagellates were the most abundant and diversified group, which accounted for the average of 56.26% and 53.70% DNA reads and OTUs, respectively. Dinoflagellates were dominated by Protoperidinium, Euduboscquella, Amylax, and Paragymnodinium. Chaetoceros, Thalassiosira, and Skeletonema were abundant in diatoms, while Pedospumella and Paraphysomonas in Chrysophyceae were the most abundant genera due to their massive occurrence in some particular sites. The high abundance of Protoperidinium sequences suggested the high nutrient levels in the southern Chinese coastline. Nineteen of the detected OTUs were assigned to harmful and/or bloom-forming microalgae. The wide occurrence of the toxic dinoflagellate Azadinium poporum and high abundance of Alexandrium pacificum in some particular sites suggested the potential risk of human poisoning.  相似文献   

MSCT在邻关节骨囊肿诊断中的应用价值     

陈平有  仇俊华  陈文 《CT理论与应用研究》2011,20(3):363-369

目的：探讨邻关节骨囊肿的MSCT表现,提高对该病的术前诊断能力。方法：回顾性分析经手术病理证实的32例邻关节骨囊肿的临床及CT薄层扫描、多平面重组（MPR）表现。男20例,女12例,平均年龄42岁。结果：32例均为单发病变,共32个病灶,其中股骨头8个,胫骨近端8个,距骨6个,胫骨远端3个,腕月骨3个,股骨远端、髋臼、肱骨近端和腕舟骨各1个。病灶均位于骨内邻近关节面,病灶大小介于0.8cm×1.2cm～2.5cm×2.9cm之间。单房型26例,CT表现为圆形、类圆形或不规则形囊样低密度区,边缘清晰,均有薄层完整硬化边,相邻关节间隙无明显改变;多房型6例,病灶内有粗细不等的骨性间隔。病灶CT值20～60Hu,3个病灶内见细小气体密度影。穿透型18例,表现为病灶通过邻关节面裂隙与关节腔相通或病灶与关节旁软组织腱鞘囊肿相连;特发型14例,表现为骨内单一病灶,骨外结构正常。结论：邻关节骨囊肿有其特殊发病部位,CT表现典型,结合发病年龄和临床症状,可以作出正确的术前诊断。  相似文献   

光照及营养盐对3种赤潮甲藻吞噬营养行为的影响   总被引：3，自引：1，他引：2       下载免费PDF全文

张淑雯  欧林坚  吕颂辉  陈菊芳 《海洋科学》2011,35(4):94-99

通过在室内批量培养实验中添加活体藻类及荧光标记藻类(Fluorescent Labled Algae,FLA)的方式,研究不同光照及营养盐条件下3种赤潮甲藻米氏凯伦藻(Karenia mikimotoi)、链状亚历山大藻(alexandrium catenella)及东海原甲藻(Prorocentrum donghai...  相似文献   

Historical deposits of Alexandrium catenella resting cysts in the sediments of Queen Charlotte Sound,New Zealand     

AL MacKenzie  S Webber  AM Watts  A Tonks 《新西兰海洋与淡水研究杂志》2016,50(2):195-208

In 2011, a large repository of resting cysts of the toxic dinoflagellate Alexandrium catenella was discovered in the sediments of the Onapua/Opua inlet located off Tory Channel, Queen Charlotte Sound. The inlet is a potential source of infection for other areas, such as the major mussel-growing areas of Port Underwood and Pelorus Sound. This study aimed to establish whether the dinoflagellate was a new arrival in the Sounds or had existed unnoticed in this isolated embayment for some time. Alexandrium catenella cysts were identified to a depth of 20–21?cm within the sediment cores, corresponding to a date estimated by radioisotope (²¹⁰Pb and ¹³⁷Cs) and Pinus radiata pollen distribution to at least the mid 1970s. Over this time span, resident populations of A. catenella have not become established beyond the confines of Queen Charlotte Sound, suggesting it does not pose an imminent threat of doing so unless increasingly intense and prolonged blooms result in more widespread cyst dispersal.  相似文献