氧同位素：追踪陆架海沿岸水团变化的良好标志

对于陆架海而言除了冰体积效应,温度效应外,还有由于大陆淡水注入引起的,使δ＾１８Ｏ值负向偏移的效应,而且在低海平面时期,当沿岸水团盛行时,这种效应起主导作用。笔者将这种效应从广州的盐度效应中分离出来,称为陆架海的负值效应。     

Benthic foraminiferal δ~(13)C minimum events in the southeastern Okhotsk Sea over the last 180 ka

A total of six d13C minimum events,i.e.,VI,V,IV,III,II,and I,were observed via a stable carbon and oxygen isotope analysis of infaunal benthic foraminifera Uvigerina spp.in gravity core OS03-1 in the southeastern Okhotsk Sea over the last 180 ka.These events occurred at112–109,102–90,85–76,57–54,44–40,and 17–10 ka BP.The largest negative excursions reached 2.5%in event V and were greater than 1%in the other events.We proposed that all d13C minimum events were caused by the increase in sea surface water productivity,the weakened formation of Okhotsk Sea intermediate water,and the enhancement of the oxygen minimum zone.The negative excursions were unaffected by methane hydrate destabilization and subsequent methane release based on the results obtained by using archaeal lipid markers.     

Research on the disappearance causes of the Tenghualuo Site in Lianyungang,Jiangsu Province, China

With brilliant civilization during the transitional period from a original clan society to a state society in prehistory,the Neolithic Tenghualuo Site in Lianyungang was discovered by archaeological survey in 1989,which was titled as‘one of the nation’s ten great archeological discoveries in 2000’.However,the transgression and the anthropogenic environment deterioration have ever been employed to explain the abandonment of the site.Based on a dynasty framework established by the 14 C dating,and using the experimental methods such as micro-paleontology identification in foraminifera and charophytes, the content test of Rb and Sr,susceptibility analysis as well as granularity and sedimentary facies analysis,some researches on the sediments from the two exploration layers at Tenghualuo Site were conducted,and the following new findings have been gained:Firstly,foraminifera which are relevant to the marine environment were not found in the sediment layer,however,25 charales,which usually live in the freshwater environment,in 07LTT1 exploration samples were found.Among them,3 charales were found in the samples from the forth sediment layer below the late Longshan Cultural layer and 22 charates were from the second sediment layer above the late Longshan Cultural layer.Furthermore,5 plant seeds and 41 fungal spores,together with many carbonation holes,plant seed shells,as well as their roots and stems were also found in the second sediment layer above the late Longshan Cultural layer.Secondly,the cumulative probability curves of the sediments’granularity in both the last and its overlying culture intermittent layers have characteristics of three-phase river sediment curve,and the ratios between Rb and Sr are both quite high in samples from two layers sedimented during the disappearing time of the site.All above-mentioned evidences indicate that disappearance of the Tenghualuo Site was not related to the transgression.The late Longshan Culture of the site could be completely abandoned after a relatively long-ter     

北海外沙泻湖全新世硅藻、有孔虫组合与沉积相演化

系统分析北海外沙泻湖ＣＫ１０钻孔岩芯的硅藻、有孔虫、介形虫化石, 并进行１４Ｃ年代测定, 探讨硅藻、有孔虫组合特征、沉积相演化和地层年代。该孔全新世地层硅藻化石群自下而上划分为： Ⅰ． 波缘曲壳藻（Ａｔｈｎａｎｔｈｅｓｃｒｅｎｕｌａｔａ）—亲缘桥弯藻（Ｃｙｍ ｂｅｌｌａ ａｆｆｉｎｉｓ） —披针桥弯藻（Ｃｙｍ ． ｌａｎｃｅｏｌａｔａ） ,Ⅱ．亲缘桥弯藻—波缘曲壳藻—卵形菱形藻（Ｎｉｔｚｓｃｈｉａ ｃｏｃｃｏｎｅｉｆｏｒｍｉｓ） , Ⅲ． 亲缘桥弯藻—波缘曲壳藻—史密斯双壁藻（Ｄｉｐｌｏｎｅｉｓｓｍ ｉｔｈｉｉ）,Ⅳ． 波缘曲壳藻—亲缘桥弯藻—条纹小环藻（Ｃｙｃｌｏｔｅｌｌａ ｓｔｒｉａｔａ）, Ⅴ．卵形菱形藻—具槽直链藻（Ｍｅｌｏｓｉｒａ ｓｕｌａｔａ）—柱状小环藻（Ｃｙｃ． ｓｔｙｔｏｒｕｍ ）, Ⅵ．条纹小环藻—柱状小环藻, Ⅶ． 具槽直链藻—条纹小环藻—卵形菱形藻, Ⅷ． 柱状小环藻等８ 个硅藻组合带。有孔虫群自下而上划分为： Ⅰ． 毕克卷转虫变种（Ａｍ ｍ ｏｎｉａ ｂｅｃｃａｒｉｉ ｖａｒ．） —瘦瘪雅得虫（Ｊａｄａｍ ｍｉｎａ ｍ ａｃｒｅｓｃｅｎｓ） , Ⅱ． 毕克卷转虫变种—异地希望虫（Ｅｌｐｈｉｄｉｕｍ ａｄｖｅｎｕｍ ）—球室     

北海外沙泻湖全新世硅藻、有孔虫组合与沉积相演化

系统分析北海外沙泻湖ＣＫ１０钻孔岩芯的硅藻、有孔虫、介形虫化石,并进行＾１４℃年代测定,探讨硅藻、有孔虫组合特征、沉积相演化和地层年代。该孔全新世地层硅藻化石群自下而上划分为：Ｉ．波缘曲壳藻（Ａｔｈｎａｎｔｈｅｓ ｃｒｅｎｕｌａｔａ）－新缘桥弯藻（Ｃｙｍｂｅｌｌａ ａｆ ｆｉｎｉｓ）一披针桥弯藻（Ｃｙｍ．ｌａｎｃｅｏｌａｔａ）,Ⅱ．新缘桥弯藻一波缘曲壳藻一卵形菱形藻（Ｎｉｔｚｓｃｈｉａ ｃｏｃｏｎ     

西藏定日贡扎上白垩统的年代地层划分及评述

分别采用不同的地层学方法对西藏贡扎地区的两条相邻上白垩统剖面进行了年代地层划分.根据将建立在贡扎Ⅰ上白垩统剖面上的锶同位素演化曲线与W. H .Burke等的同时代锶同位素演化曲线对比,剖面上岗巴村口组顶界年龄值约为81.4 Ma;根据在贡扎Ⅱ剖面上划分出的12个浮游有孔虫化石带确定的岗巴村口组顶界年龄值约为67.0 Ma.作者认为岗巴村口组顶界年龄值存在明显差别是受诸多因素影响,在对地层进行年代地层研究中,要不断提高各种地层学方法的分辨率,并尽可能采用综合的地层学方法.     

Discovery of Late Cretaceous foraminifera in the Songliao Basin: Evidence from SK-1 and implications for identifying seawater incursions

The Songliao Basin is the largest oil-bearing basin in China.In the absence of sufficient evidence,the possibility of seawater incursion(s) into the Songliao Basin remains controversial.Recently,we discovered relatively abundant foraminifera fossils from units 1 and 2 of the Nenjiang Formation of borehole SK-1.Benthic foraminifera (Gavlinella sp.,Anomalinoides sp.,Pullenia sp.,Haplophragmoides sp.,Karrorulina hokkaidoana,Clavulinoides sp.),as well as planktonic foraminifera (Archaeoglobigerina blowi,Archaeoglobigerina cretacea and Hedbergella flandrini),were identified.These fossils were widely distributed in the marine Cretaceous.According to the global distribution of the above-mentioned planktonic foraminifera,the age of these fossil bearing strata appears to be Late Coniacian to Santonian.More importantly,these foraminifera provide direct evidence for marine water incursions into the Songliao Basin during deposition of the Lower Nenjiang Formation.     

Geological records of marine environmental changes in the southern Okinawa Trough

Indexes of sediment grain size,sedimentation rates,geochemical composition,heavy,minerals,benthic foraminiferal fauna,indicator species of the Kuroshio Current,paleo-SST and carbonate dissolution of core E017 conformably suggest a great marine environmental change occurring at about 10.1-9.2cal.kaBP in the southern Okinawa Trough,which may correspond to the strengthening of the Kuroshio Warm Current and re-entering the Okinawa Trough through the sea area off northeast Taiwan.The invasion of Kuroshio current has experienced a process of gradual strengthening and then weakening,and its intensity became more fluctuation during the last 5000 years.Compared to the transition of sediment grain size,geochemical composition and heavy minerals,the foraminiferal faunas show a 900-year lag,which may indicate that the invasion of Kuroshio Current and the consequent sea surface and deep-water environmental chanages is a gradual process,and fauna has an obvious lag compared to environment altering.The carbonate dissolution of the Okinawa Trough has had an apparent strengthening since 9.2cal.kaBP,and reached a maximum in the late 3000 years,which may be caued by the deep-water environmental changes due to the invasion of Kuroshio Current.