Macrofauna Communities in the Eastern Mediterranean Deep Sea

Abstract. During two expeditions with RV ‘Meteor’ in summer 1993 and winter 1997/98 the structural and functional diversity of the benthic system of the highly oligotrophic eastern Mediterranean deep sea was investigated. The macrofauna communities were dominated by polychaetes even at the deepest stations. The fauna at shallow stations was dominated by surface deposit feeders, whereas subsurface deposit feeders and predators generally increased with depth. A high percentage of suspension‐feeding Porifera was found in the Levantine Basin. Mean abundance and number of taxa of both expeditions were significantly correlated to depth and distance to the nearest coast as well as to the total organic carbon (TOC) content in sediments. Numbers of taxa and abundance decreased generally with depth, although lowest numbers were not found at the deepest stations but in the extremely oligotrophic Levantine and Ierapetra Basin. Biomass measured during the second cruise was extremely low in the Ierapetra Basin and comparable to other extreme oligotrophic seas. The significant correlations found for TOC contents and macrofauna with distance to coast during both expeditions apparently reflect the role of hydrographically governed transport of organic matter produced in coastal regions into greater and extreme depths of the Mediterranean Sea. Seasonal differences in macrofauna communities due to seasonal differences in food supply were not found. However, recent large‐scale hydrographic changes (Eastern Mediterranean Transient, EMT) might change the oligotrophy and, thus, the structure of the benthic communities in the Eastern Mediterranean deep sea.     

The mapping methods and division of tectonic units of the regional tectonic map in the eastern China seas and adjacent regions

The geological-geophysical map series of the eastern China seas and adjacent region (1:1 000 000) will be published in the late half year of 2009. The regional tectonic map is one of the main professional maps. The Mapping methods, the division method of geological tectonic units and the main geological tectonic units are mainly discussed. The strata from Pliocene to Holocene are peeled off so as to display the Pre-Pliocene structures. In basins, isopaches are drawn for the Cenozoic deposits. The plate tectonic theory and present tectonic pattern are adopted as the priorities in tectonic division. As to the division of intraplate tectonic units, it is a revision, complement and improvement of previous dividing systems, and the nomenclature for each tectonic unit follows the current system in China. The first-order tectonic unit is plate (Pacific Plate, Eurasian Plate and Philippine Sea Plate). The second-order tectonic unit is tectonic domain (East Asian continental tectonic domain,East Asian continental margin tectonic domain and west Pacific tectonic domain). The Philippine Sea Plate and the west part of the Pacific Plate are called the West Pacific tectonic domain. The part of the Eurasian Plate involved in this study area can be further divided into East Asian continental tectonic domain and East Asian continental margin tectonic domain. The East Asian continental margin domain is composed of the Ryukyu island arc, the Okinawa Trough back-arc basin and the back-arc basin of Sea of Japan. The East Asian continental tectonic domain in this study area is composed of the Sino-Korea Massif, the Changjiang River (Yangtze) Massif and South China Massif. In turn, these massifs consist of basins, folded belts or uplift zones. The basins,the folded belts or the uplift zones are further divided into uplifts and depressions made up of sags and swells.     

南海东部深海沉积中的孢粉研究及其古环境意义

通过对南海东部 149 站深海柱状剖面的孢粉、藻类研究,根据孢粉成分的变化将该孔沉积层从下至上划分为 4 个孢粉组合带.1 带:Pinus-Quercus(常绿)-Umbellferae-Gramineae-Pteris 孢粉带(407～270cm);2 带:Dacrydium-Quercus-Cyathea-Pinus-Polypodiaceae 孢粉带(270～105 cm);3 带:Pinus-Polypodiaceae-Quercus(常绿)-Pteridium 孢粉带(105～30 cm);4 带:Gleditsia-Cyathea-Pinus-Polypodiaceae 孢粉带(30～0 cm).并相应恢复了南海东部 7.5 万 a 以来 4 个植被、气候、古环境演替阶段:热带北缘半常绿季雨林、热带季雨林、热带北缘半常绿季雨林和热带季雨林.结合氧同位素测年资料,对 149 站柱状地层时代作了划分.     

冀西安妥岭斑岩型钼矿成矿地质条件浅析

安妥岭钼矿位于燕辽钼（铜）成矿带南端,与附近的野弧斑岩型钼矿等具有相同的地质背景和成矿条件。文章阐述了古结晶基底、中生代岩体以及NNE、NW和近EW向构造与成矿的关系,提出安妥岭钼矿是在斑岩型矿床基础上,叠加了主要沿NW向构造发育的岩浆热液成矿作用所形成的具有复杂成矿系列的非典型斑岩钼矿床。     

20世纪90年代中国东西部土地利用变化时空特征分析

在覆盖全国的1km栅格土地利用本底与动态成分数据时空信息平台支持下,应用土地利用动态度模型,分别计算了全国及东西部地区土地利用一级类型的单一和综合动态度,并分析了土地利用动态度的空间格局。通过分析东西部土地利用类型变化特征和土地利用类型转换特征,对20世纪90年代中国东西部土地利用变化过程的时空特征进行了全面分析,揭示了东西部地区土地利用变化的时空规律。并对主要土地利用类型变化的原因进行了分析。     

城市化进程中平原河网地区河流结构特征及其分类方法探讨

平原河网地区河流结构发育受到自然条件和城市化的双重影响。依据遥感解译数据,围绕城市化水平、河流形态、河流结构和河流调蓄功能四个维度,就建成区面积比例、河流长宽分布、河系分维、河流调蓄能力等具体指标,分析了城市化水平和土地利用特征不同区域的河流空间形态、结构特征和功能状态,探讨了城市化进程中平原河网地区河流结构的可能演化轨迹,尝试建立了城市化影响下平原河网地区河流结构分类方法,提出了城市河流综合整治过程中应充分重视保护自然河流结构,注重发挥河流综合功能等观点。     

东昆仑山小南川岩体裂变径迹年代与中新世晚期以来的构造地貌演化

对昆仑垭口地区小南川岩体7件样品进行磷灰石裂变径迹年代学测试, 分析了岩体的冷却过程及岩体的剥露与构造地貌演化的关系.结果表明东昆仑山区中新世晚期视剥蚀速率极为缓慢, 为0.020~0.035mm/a, 反映的是构造隆升作用微弱、地貌缓和的地质环境, 因而构造隆升速率与低的视剥蚀速率相当.上新世以来小南川岩体突发性快速隆升冷却, 造成超过3km的物质揭顶, 这不是由单纯的剥蚀过程导致, 而是反映了昆仑山上新世以来的强烈构造隆升驱动下的成山作用过程.岩体上新世的裂变径迹年龄与近东西向的昆仑河-野牛沟谷地断裂断陷、昆仑垭口盆地断陷以及后期西大滩谷地断陷的综合构造地貌演化有密切的成因联系.此外裂变径迹年龄的空间分布格局反映了区域性的差异隆升作用, 由南向北、由西向东, 隆升和剥蚀作用逐渐衰减, 这与东昆仑山南北向以及东、西昆仑山之间地貌发育的差异性以及新生代火山作用分布是吻合的.      

基于印度洋海温信号的我国西北地区东部夏季降水组合降尺度预测方法研究

利用国家气候中心第二代气候模式预测业务系统(BCC-CPSv2)预测产品,引入印度洋海温信号,采用组合降尺度方法建立了西北地区东部汛期降水预测模型。该预测模型对1991—2017年西北地区东部夏季降水的回报技巧较BCC-CPSv2预测技巧显著提高,空间相关系数由0.42提高到0.75,均方根误差明显减小,最多下降达80%。预测模型对降水空间分布型的预测能力较好,很好地回报了典型年份（1987年和2010年）夏季的降水距平百分率分布。通过抓住气象变量的空间分布特征,组合降尺度方法可以修正动力模式产品的预测误差,为西北地区东部夏季降水预测提供科学依据和技术支持,具有较好的应用前景。     

Refining accretionary orogen models for the Tasmanides of eastern Australia

The well-known southwest-to-northeast younging of stratigraphy over a present-day cross strike distance of >1500 km in the southern Tasmanides of eastern Australia has been used to argue for models of accretionary orogenesis behind a continually eastwards-rolling paleo-Pacific plate. However, these accretionary models need modification, since the oldest (ca 530 Ma) outcrops of Cambrian supra-subduction zone rocks occur in the outboard New England Orogen, now ～900 km east of the next oldest (520–510 Ma) supra-subduction zone rocks. This is not consistent with simple, continuous easterly rollback. Instead, the southern Tasmanides contain an early history characterised by a westwards-migrating margin between ca 530 and ca 520 Ma, followed by rapid eastwards rollback of the paleo-Pacific plate from 520 to 502 Ma that opened a vast backarc basin ～2000 km across that has never been closed. From the Ordovician through to the end of the Carboniferous, the almost vertical stacking of continental margin arcs (within a hundred kilometres of each other) in the New England Orogen indicates a constant west-dipping plate boundary in a Gondwana reference frame. Although the actual position of the boundary is inferred to have undergone contraction-related advances and extension-related retreats, these movements are estimated to be ～250 km or less. Rollback in the early Permian was never completely reversed, so that late Permian–Triassic to Cretaceous arcs lie farther east, in the very eastern part of eastern Australia, with rifted fragments occurring in the Lord Howe Rise and in New Zealand. The northern Tasmanides are even more anomalous, since they missed out on the middle Cambrian plate boundary retreat seen in the south. As a result, their Cambrian-to-Devonian history is concentrated in a ～300 km wide strip immediately west of Precambrian cratonic Australia and above Precambrian basement. The presence in this narrow region of Ordovician to Carboniferous continental margin arcs and backarc basins also implies a virtually stationary plate boundary in a Gondwana frame of reference. This bipolar character of the Tasmanides suggests the presence of a segmented paleo-Pacific Plate, with major transform faults propagating into the Tasmanides as tear faults that were favourably oriented for the formation of local supra-subduction zone systems and for subsequent intraplate north–south shortening. In this interpretation of the Tasmanides, Lower–Middle Ordovician quartz-rich turbidites accumulated as submarine fan sequences, and do not represent multiple subduction complexes developed above subduction zones lying behind the plate boundary. Indeed, the Tasmanides are characterised by the general absence of material accreted from the paleo-Pacific plate and by the dominance of craton-derived, recycled sedimentary rocks.     

Gas generation and expulsion characteristics of Middle–Upper Triassic source rocks,eastern Kuqa Depression,Tarim Basin,China: implications for shale gas resource potential

Frontier exploration in the Kuqa Depression, western China, has identified the continuous tight-sand gas accumulation in the Lower Cretaceous and Lower Jurassic as a major unconventional gas pool. However, assessment of the shale gas resource in the Kuqa Depression is new. The shale succession in the Middle–Upper Triassic comprises the Taliqike Formation (T₃t), the Huangshanjie Formation (T₃h) and the middle–upper Karamay Formation (T_2–3k), with an average accumulated thickness of 260 m. The high-quality shale is dominated by type III kerogen with high maturity and an average original total organic carbon (TOC) of about 2.68 wt%. An improved hydrocarbon generation and expulsion model was applied to this self-contained source–reservoir system to reveal the gas generation and expulsion (intensity, efficiency and volume) characteristics of Middle–Upper Triassic source rocks. The maximum volume of shale gas in the source rocks was obtained by determining the difference between generation and expulsion volumes. The results indicate that source rocks reached the hydrocarbon expulsion threshold of 1.1% VR and the hydrocarbon generation and expulsion reached their peak at 1.0% VR and 1.28% VR, with the maximum rate of 56 mg HC/0.1% TOC and 62.8 mg HC/0.1% TOC, respectively. The volumes of gas generation and expulsion from Middle–Upper Triassic source rocks were 12.02 × 10¹² m³ and 5.98 × 10¹² m³, respectively, with the residual volume of 6.04 × 10¹² m³, giving an average gas expulsion efficiency of 44.38% and retention efficiency of 55.62%. Based on the gas generation and expulsion characteristics, the predicted shale gas potential volume is 6.04 × 10¹² m³, indicating a significant shale gas resource in the Middle–Upper Triassic in the eastern Kuqa Depression.