Spatiotemporal distribution of sea-island prehistoric dune sites,Holocene sea levels,and aeolian sand activities in Fujian Province,China

The lower reaches of the Minjiang River and its adjacent areas were among the most active prehistoric archaeological areas in Fujian Province. The accumulation types of Neolithic archaeological strata are roughly divided into dune sites and dune/shell mound sites. The sites can also be roughly divided into estuarine, coastal, and sea-island sites based on their geomorphic features. The cultural development of these prehistoric sites is of great significance for understanding the migration and spread of Austronesian civilization. Based on luminescence dating of typical Neolithic sites on Haitan Island, their quartz-OSL (optically stimulated luminecesence) burial ages were determined. Synthesizing previously published results, the temporospatial distribution characteristics of the sea-island sites on Haitan Island are discussed, and the relationship between Neolithic human activities and regional geomorphic processes is analyzed. The results show that: (1) the spatial and temporal distribution of the Haitan Island Neolithic sites are closely related to small-scale geomorphic features and are controlled by mesoscale geomorphic processes. The sites were mainly distributed in the foothills of two high hills along an NNE-SSW trend. With an increase in altitude, the features were distributed as “single site (I) - superimposed site - single site (II)” and appear successively. Single type sites (I) mainly appeared at low sea level, whereas single type sites (II) mainly appeared at high sea level. Superimposed sites were not subject to sea level changes. The relative elevation of the superimposed sites in the study area indicates the optimal residential area for human activities in the region. The single site with an elevation lower than the optimal residential area was mainly restricted by the lowest residential area, whereas the single site at a higher elevation than the optimal residential area was mainly affected by livelihood patterns. (2) High sea level caused by the “backwater effect” in low latitude areas in the southern hemisphere, and coastal aeolian sand activity influenced by sea level fluctuations in the middle Holocene correspond well with human activities recorded in the cultural stratigraphy of sea-island type sites. The altitude of coastal aeolian sand accumulation can be used as an indirect index to estimate the age of coastal dunes.     

The earliest well-dated archeological site in the hyper-arid Tarim Basin and its implications for prehistoric human migration and climatic change

The routes and timing of human occupation of the Tibetan Plateau (TP) are crucial for understanding the evolution of Tibetan populations and associated paleoclimatic conditions. Many archeological sites have been found in/around the Tarim Basin, on the northern margin of the Tibetan Plateau. Unfortunately, most of these sites are surface sites and cannot be directly dated. Their ages can only be estimated based on imprecise artifact comparisons. We recently found and dated an archeological site on a terrace along the Keriya River. Our ages indicate that the site was occupied at ~ 7.0–7.6 ka, making it the earliest well-dated archeological site yet identified in the Tarim Basin. This suggests that early human foragers migrated into this region prior to ~ 7.0–7.6 ka during the early to mid-Holocene climatic optimum, which may have provided the impetus for populating the region. We hypothesize that the Keriya River, together with the other rivers originating from the TP, may have served as access routes onto the TP for early human foragers. These rivers may also have served as stepping stones for migration further west into the now hyper-arid regions of the Tarim Basin, leading ultimately to the development of the Silk Road.     

琼东南盆地北礁凹陷梅山组顶部丘形反射特征及成因分析

南海琼东南盆地北礁凹陷中中新统梅山组顶部丘形反射目前引起广泛关注,前人推测为生物礁、重力蠕动与底流叠加成因、等深积丘等。本文通过钻井资料、二维、三维地震资料精细刻画丘形反射（残丘）和丘间水道特征及其成因。残丘及水道在北礁凸起不发育,在边缘斜坡中部和高地较发育,且有向高地两边规模减小趋势,不具对称性,残丘和水道呈平行-亚平行近E-W向展布,局部有合并分叉现象,与北礁凸起走向呈一小角度;丘宽562~1 223 m,丘高29~87 m,丘长10 km左右,存在丘翼削蚀,水道底蚀现象。地震属性分析表明三维工区西南部残丘间水道由砂泥岩互层充填,形成长条形强振幅,而残丘为中-低振幅;地震、钻井资料分析表明丘形反射（残丘）由钙质泥岩和泥岩组成,属于半深海沉积,且残丘内部波阻抗为5.0×106~6.5×106kg/m3·m/s,低于火山岩、灰岩波阻抗,属于砂泥岩地层范畴;根据梅山组下段水道由西向东强振幅变弱、分叉、前积反射和海山附近底流（等深流）沉积剥蚀特征综合判定底流古流向自西向东,根据海山两翼地震反射特征推测底流可追溯至晚中新世早期（11.6 Ma BP）,综合分析认为,研究区中中新统梅山组丘形反射是晚中新世早期底流切割梅山组地层形成的残丘。     

Thérèse Mound: a case study of coral bank development in the Belgica Mound Province,Porcupine Seabight

High-resolution seismic profiles, swath bathymetry, side-scan sonar data and video imageries are analysed in this detailed study of five carbonate mounds from the Belgica mound province with special emphasis on the well-surveyed Thérèse Mound. The selected mounds are located in the deepest part of the Belgica mound province at water depths of 950 m. Seismic data illustrate that the underlying geology is characterised by drift sedimentation in a general northerly flowing current regime. Sigmoidal sediment bodies create local slope breaks on the most recent local erosional surface, which act as the mound base. No preferential mound substratum is observed, neither is there any indication for deep geological controls on coral bank development. Seismic evidence suggests that the start-up of the coral bank development was shortly after a major erosional event of Late Pliocene–Quaternary age. The coral bank geometry has been clearly affected by the local topography of this erosional base and the prevailing current regime. The summits of the coral banks are relatively flat and the flanks are steepest on their upper slopes. Deposition of the encased drift sequence has been influenced by the coral bank topography. Sediment waves are formed besides the coral banks and are the most pronounced bedforms. These seabed structures are probably induced by bottom current up to 1 m/s. Large sediment waves are colonised by living corals and might represent the initial phase of coral bank development. The biological facies distribution of the coral banks illustrate a living coral cap on the summit and upper slope and a decline of living coral populations toward the lower flanks. The data suggest that the development of the coral banks in this area is clearly an interaction between biological growth processes and drift deposition both influenced by the local topography and current regime.     

塔中I号断裂带顺6井上奥陶统取芯段古生物群落演化及其古生态意义

本文研究了塔中I号断裂带西北端顺6井上奥陶统地层第一次取芯段的古生物群落,共划分出5种类型:分别为隐蓝细菌群落、海德菌-疑源类-四分珊瑚群落、四分珊瑚-海得菌群落、四分珊瑚-红藻类稀群落、棘皮类稀群落,各群落的生物组成均不同。确定礁群落有3种:隐蓝细菌群落、海德菌-疑源类-四分珊瑚群落和四分珊瑚-海得菌群落。隐蓝细菌群落发育于台地边缘较深水的灰泥丘,海德菌-疑源类-四分珊瑚和四分珊瑚-海德菌群落发育于台地边缘较浅水的生物礁,红藻类稀群落和棘皮类稀群落发育于台地边缘滩。灰泥丘、四分珊瑚骨架礁和海德菌障积礁地层溶蚀孔洞很发育,但是均被亮晶方解石充填。生屑砂屑滩中的溶孔具有残余孔隙,可能构成油气的储集空间。     

巴西桑托斯盆地湖相微生物碳酸盐岩储层内幕刻画及定量表征方法

微生物碳酸盐岩研究是近年来国内外关注的热点,虽然已经取得了一定的成果和认识,但是在储层精细描述方面研究相对薄弱。以巴西桑托斯盆地盐下白垩系湖相微生物碳酸盐岩油田为例,利用露头、岩心、测井、地震等资料综合分析了研究区储层沉积特征、岩性、物性特征及其主控因素,并在此基础上对储集体内幕结构进行分类和描述,初步建立其定量表征方法。结果表明: ①研究区由3个独立的碳酸盐岩台地沉积组成,可细分为微生物灰岩丘、高能颗粒滩、丘间洼地和台间洼地4个亚相; ②微生物灰岩、生物碎屑颗粒灰岩、介壳颗粒灰岩、层纹岩等是主要的储层岩石类型; ③储层物性较好,孔隙度4%~27%,集中在5%~15%,平均12.5%; 渗透率为(0.01~3 000)×10-3 µm2,平均120×10-3 µm2; ④储层发育受沉积和成岩双重作用,古构造控制优势储层的发育,准同生期溶蚀作用对储层改造作用加强,周期性暴露溶蚀使生物碎屑颗粒填充至丘间洼地形成高孔高渗条带; ⑤研究区储层的内幕结构以微生物灰岩丘群为基础,细分为丘基、丘核、丘翼、丘间和丘间甜点。建立以沉积相和成岩相控制因素为基础的丘群组合模式定量表征方法,在应用中获得了较好的效果。