Reef exploration in the East Sengkang Basin,Sulawesi, Indonesia

Reconnaissance seismic shot in 1971/72 showed a number of well defined seismic anomalies within the East Sengkang Basin which were interpreted as buried reefs. Subsequent fieldwork revealed that Upper Miocene reefs outcropped along the southern margin of the basin. A drilling programme in 1975 and 1976 proved the presence of shallow, gas-bearing, Upper Miocene reefs in the northern part of the basin. Seismic acquisition and drilling during 1981 confirmed the economic significance of these discoveries, with four separate accumulations containing about 750 × 10⁹ cubic feet of dry gas in place at an average depth of 700 m. Kampung Baru is the largest field and contains over half the total, both reservoir quality and gas deliverability are excellent. Deposition in the East Sengkang Basin probably started during the Early Miocene. A sequence of Lower Miocene mudstones and limestones unconformably overlies acoustic basement which consists of Eocene volcanics. During the tectonically active Middle Miocene, deposition was interrupted by two periods of deformation and erosion. Carbonate deposition became established in the Late Miocene with widespread development of platform limestones throughout the East Sengkang Basin. Thick pinnacle reef complexes developed in the areas where reef growth could keep pace with the relative rise in sea level. Most reef growth ceased at the end of the Miocene and subsequent renewed clastic sedimentation covered the irregular limestone surface. Late Pliocene regression culminated in the Holocene with erosion. The Walanae fault zone, part of a major regional sinistral strike-slip system, separates the East and West Sengkang Basins. Both normal and reverse faulting are inferred from seismic data and post Late Pliocene reverse faulting is seen in outcrop.     

Diversity and abundance of mangrove fiddle crabs, genus Uca (Decapoda, Ocypodidae) at a mangrove in Kema, North Sulawesi, Indonesia

Mangrove ecosystems are sites with high biodiversity of benthic fauna, and fiddler crabs (genus Uca) are common benthic fauna in mangroves. The North Sulawesi in Indonesia has a good condition of mangrove while the information of the fiddler crabs is still limited. Manual samplings were conducted in wet, dry and transient seasons at a mangrove in Kema, North Sulawesi to investigate the species composition, density and distribution pattern of fiddler crabs. A total of 168 individuals, subjected to eight species of genus Uca crabs were collected at the mangrove, with U. triangularis having the highest abundance and U. annulipes having the lowest abundance. The densities of fiddle crabs were 27.56 ind./m², 32.89 ind./m² and 14.22 ind./m² at the seaward, middle and landward zones, respectively, and the density was higher in dry and wet seasons than in transient season.     

印度尼西亚北苏拉威西红树林生态系统碳库研究

近年来的研究指出红树林在海岸带碳固定和碳储存方面发挥着重要的作用。尽管印度尼西亚的红树林面积在全球占很大的比重,对于该地区红树林的有机碳储量和土壤有机碳来源的认识仍有限。本研究调查了印度尼西亚北苏拉威西海洋型的Wori红树林中生态系统有机碳储量及其空间分布特征,以及土壤有机碳的来源,以期加深该地区红树林“蓝碳”功能的认识。研究结果显示,Wori红树林0-50cm深度土壤中有机碳储量为15.4 kg/m²,占生态系统碳储量的主要部分（65%）。红树植物生物量和生态系统碳储量分别为8.3 kg/m²和23.7 kg/m²。土壤有机碳储量在不同离岸距离的采样站位中未表现出显著的空间分布差异,而生物量碳储量则在外滩最高。¹³C稳定同位素分析结果表明红树林土壤中蓄积的有机碳主要来源于红树林有机质,而潮水中的悬浮有机质和红树林外缘的海草并不构成红树林土壤有机碳的重要来源,它们的贡献者都低于20%。研究结果进一步证实了热带地区海洋型红树林湿地在碳储存以及红树植物对碳固定方面的重要性。     

Seismic geomorphology and depositional system of delta and terminal fan: A case study of the Neogene Shawan Formation in the Chepaizi Uplift,Junggar Basin,China

The mainpurpose of this article is to demonstrate the utility of stratal slice images for exploring the sequence stratigraphy and sedimentology of complex depositional systems. A seismic sedimentological study was performed to map sediment dispersal characteristics of the Neogene Shawan Formation in the Chepaizi Uplift of the Junggar Basin, China. The Chepaizi Uplift is developed on the Carboniferous igneous rock basement that lies at the western boundary of the Junggar Basin. The data sources primarily include lithology, well-logging and seismic data. In the main target strata, the Neogene Shawan Formation can be divided into three fourth-order sequences (SQN₁s₁, SQN₁s₂, and SQN₁s₃), and the sequence SQN₁s₁ is subdivided into three fifth-order sequences (SQN₁s₁¹, SQN₁s₁², and SQN₁s₁³). Based on the established fine-sequence stratigraphic framework, the sedimentary facies types have been identified, they are shallow braided-river deltas, fan deltas, littoral and sublittoral lakes, braided rivers, and terminal fans. Then, stratal slices have been used to clearly depict the boundaries of sedimentary facies. Accurate results have been obtained that characterize braided river channels, terminal fans, littoral and sublittoral lake beaches, and subaqueous distributary channels in the braided-river delta front. Additionally, this seismic sedimentology study reflects variations in source area and evolution history.     

新近纪深海大洋红层的分布分类及成因

新近纪大洋红层是一种在氧化条件下形成的红色-粉色-棕色海洋沉积物.白垩纪大洋红层研究成果众多,然而新近纪大洋红层研究缺乏系统的分析和总结.本文以新近纪大洋红层为研究对象,通过对全球大洋钻探井位资料的分析,发现39个钻井含有新近纪大洋红层.通过对不同大洋区域、不同钻井内93个红层离散样品的主量元素CaO,Al2O3和Si...     

基于Argo、XBT数据的苏拉威西海温盐特征分析

综合利用Argo温、盐度观测剖面资料,以及中国南极科学考察时沿途获取的XBT温度剖面,分析探讨了苏拉威西海域(117°E-127°E,0°-8°N)上表层温度和盐度的气候态分布和变化特征.结果 表明,苏拉威西海域的温度范围约为2.5℃～30℃,盐度约为33.2‰ ～ 35.1‰.与垂向变化相比,温、盐度水平梯度均较小,...     

渤海海域的上第三系油气研究

综述了渤海湾盆地沉积与构造活动在时间与空间上的迁移与演化、烃源岩与储盖层的空间分布规律，结合盆地内的勘探现状分析了渤海湾海域上第三系的油气远景。认为盆地内凸起、低凸起以上第三系为主体，伴有东营组和前第三系油气藏的复式油气聚集带是目前渤海油气勘探最现实的有利目标。     

Distribution of the Neogene Utsira Sand and the succeeding deposits in the Viking Graben area, North Sea

The sandy quartzose parts of the Utsira Formation, the Middle Miocene to mid Pliocene Utsira Sand, extends north–south along the Viking Graben near the UK/Norwegian median line for more than 450 km and 75–130 km east–west. The Utsira Sand is located in basin-restricted seismic depocentres, east of and below prograding sandy units from the Shetland Platform area with Hutton Sands. The Utsira Sand reaches thicknesses up to ca. 300 m in the southern depocentre and 200 m in the two northern depocentres with sedimentation rates up to 2–4 cm/ka. Succeeding Plio–Pleistocene is divided into seismic units, including Base Upper Pliocene, Shale Drape, Prograding Complex and Pleistocene. The units mainly consist of clay, but locally minor sands occur, especially at toes of prograding clinoforms (bottom-set sands) and in the Pleistocene parts, and the total thickness covering the Utsira Sand is in most places more than 800 m, but thins towards the margins.     

印度尼西亚北苏拉威西蓝碧海峡浮游动物种类组成及分布

Based on oceanographic survey data in June 2012 in the Lembeh Strait, the zooplankton ecological characteristics such as species composition, individual abundance, dominant species and distribution were analyzed. The results showed that 183 species(including 4 sp.) had been recognized, most of them belonged to copepoda.Cnidaria followed with 43 species(including 1 sp.) were identified. The average abundance of zooplankton was(150.47±58.91) ind./m~3. As to the horizontal distribution, the abundance of the zooplankton was higher in the southern waters than in the northern waters. The dominant species in the study area were Lensia subtiloides,Sagitta enflata, Lucifer intermedius, Oikopleura rufescens, Diphyes chamissoni, Creseis acicula, Subeucalanus subcrassus, Temora discaudata, Aglaura hemistoma, Doliolum denticulatum, Canthocalanus pauper, Oikopleura longicauda and Nanomia bijuga. Zooplankton biodiversity indexes were higher in study area than previous study in the other regions. The findings from this study provide important baseline information for future research and monitoring programs.     

印尼北苏拉威西海蓝碧海峡水团性质的南北差异

Two field observations were conducted around the Lembeh Strait in September 2015 and 2016, respectively.Evidences indicate that seawater around the Lembeh Strait is consisted of North Pacific Tropical Water(NPTW),North Pacific Intermediate Water(NPIW), North Pacific Tropical Intermediate Water(NPTIW) and Antarctic Intermediate Water(AAIW). Around the Lembeh Strait, there exist some north-south differences in terms of water mass properties. NPTIW is only found in the southern Lembeh Strait. Water mass with the salinity of 34.6 is only detected at 200–240 m between NPTW and NPTIW in the southern Lembeh Strait, and results from the process of mixing between the saltier water transported from the South Pacific Ocean and the lighter water from the North Pacific Ocean and Sulawesi Sea. According to the analysis on mixing layer depth, it is indicated that there exists an onshore surface current in the northern Lembeh Strait and the surface current in the Lembeh Strait is southward.These dramatic differences of water masses demonstrate that the less water exchange has been occurred between the north and south of Lembeh Strait. In 2015, the positive wind stress curl covering the northern Lembeh Strait induces the shoaling of thermocline and deepening of NPIW, which show that the north-south difference of airsea system is possible of inducing north-south differences of seawater properties.     

渤海湾盆地黄河口凹陷中洼断裂生长及其对新近系油气富集的控制作用

黄河口凹陷是渤海海域重要的富烃凹陷,区域主要的烃源岩沙三段在明化镇组沉积时期开始大规模生排烃,此时研究区内断裂发育,活动强度较高,因此,断裂有效性分析是确定区域油气输导体系、判断油气输导运移成藏的重要研究内容。通过三维地震数据及钻井分析,对黄河口凹陷中洼断裂分布、活动性及生长演化进行了系统的分析,结合区域烃源岩分布及钻井油气分布特征,总结断裂对新近系油气富集的控制作用。研究表明,黄河口凹陷中洼断裂活动生长具有“先变弱再变强”的特征−从沙河街组沉积时期到馆陶组沉积时期断裂活动强度逐渐减弱,断裂活动区域逐渐缩小;明化镇组沉积时,中洼断裂活动增强,区域内断裂全面活跃。研究区早期断裂多以长度短、断距小为特征;晚期洼陷中心联结组合形成大型断裂,油源断裂沟通源储,大部分油气沿着断裂运移至浅层馆陶及明化镇组砂体中,再向两侧砂体构造高部位运移,而南部缓坡带和北部陡坡带因为断裂活动速率不同而具有不同的油气聚集特征;南部缓坡带断裂晚期活动速率不高,能够对油气进行有效封堵,自深凹而来的油气沿着砂体构造脊在缓坡带馆陶及明化镇组砂体中聚集成藏;而北部陡坡带晚期断裂活动速率高,油气在断裂附近合适的明化镇组浅层圈闭中成藏。     

Structural styles and tectonic evolution of the Seram Trough, Indonesia

The Seram Trough is located in the northern part of the Banda Arc-Australian collision zone in eastern Indonesia and is currently the site of contraction between the Bird's Head of New Guinea and Seram Island. It has been interpreted as a subduction trench, an intra-continental thrust zone and foredeep, and a zone of strike-slip faulting. Recently acquired 2D seismic lines clarify its tectonic evolution and relationship to the Bird's Head. Folding in the Early Pliocene formed an anticlinorium running from Misool to the Onin Peninsula of Irian Jaya and produced a newly recognised angular unconformity. The unconformity truncates sediments as old as Middle Jurassic and is an ancient topographic surface with significant relief. It was later folded and now dips south towards the trough where it is covered by up to 3 km of sediments. Initial tilting of the unconformity surface was accompanied by deposition of a transgressive sequence which can be traced into the trough. This is overlain by two sequences which prograde towards the trough. These sequences show progressive rotation of the unconformity surface, gravitational displacement of sediments into the trough, and thrusting which continues to the present day. Contraction occurred in the trough after the Early Pliocene and is younger than the previously suggested Late Miocene age. Thrust faults in the trough deform sediments deposited above the unconformity and detach at the unconformity surface. On Seram thrust faults repeat Mesozoic–Miocene sequences and probably detach at their contact with metamorphic basement. The detachment surface must cut through the Mesozoic-Miocene sequence between Seram and the trough. This work suggests the Seram Trough is not a subduction trench but a foredeep produced in response to loading by the developing fold and thrust belt of Seram, with an associated peripheral bulge to the north. The Seram Trough is interpreted to be a very young zone of thrusting within the Australian continental margin.     

Hydrocarbon accumulation model for Neogene traps in the Chengdao area,Bohai Bay Basin,China

Chengdao is an offshore area in the Bohai Bay Basin that contains approximately 25.7 × 10⁸ bbl of oil and gas reserves within the sandstone reservoirs in Neogene strata. However, previous predictions of hydrocarbon accumulation in Neogene traps are inaccurate, resulting in a current failure rate of 50% when drilling for hydrocarbons in this area. To build an improved exploration model for Neogene traps, we select 92 traps from Neogene strata in the Chengdao area to quantify the filling degree, which is an indicator of hydrocarbon accumulation efficiency. The quantified filling degree is based on actual geological and exploration data and differs significantly among various trap types. The filling degree of traps also varies significantly with their structural locations and decreases generally from the northwest to the southeast along the Chengbei Fault zone. Vertically, the filling degree is highly heterogeneous, initially increasing from the bottom to the middle of Neogene strata and then decreasing towards the top of the strata. These Neogene hydrocarbon reservoirs are sourced from the Paleogene, and as they lay vertically away from the source rocks, their hydrocarbon enrichment is constrained largely by hydrocarbon migration distance and vertical migration pathways. The sealing capacity of faults and cap rocks, sandbody orientation and reservoir sedimentary facies determine the maximum column height, which in turn affects the amount of hydrocarbon accumulation within these traps. A scatter plot analysis of individual controls and volumetric filling for each trap type is compiled using multivariate linear regression analysis to quantify controls and the dominant control of hydrocarbon accumulation is determined.     

Beta diversity of tropical marine benthic assemblages in the Spermonde Archipelago, Indonesia

In order to preserve diversity it is essential to understand how assemblages change across space. Despite this fact, we still know very little about how marine diversity is spatially distributed, especially among lesser‐studied invertebrate taxa. In the present study beta‐diversity patterns of sea urchins, sponges, mushroom corals and larger foraminifera were assessed in the Spermonde Archipelago (Indonesia). Using ordinations we showed that the inshore zone (<5 km offshore), midshore zone (5 < x < 30 km offshore) and distance offshore zone (>30 km offshore) all contained distinct assemblages of sponges and corals, while only foraminifera assemblages from the inshore (<5 km offshore) zone were distinct. There was a significant spatial pattern of community similarity for all taxa surveyed, but this pattern proved to be wholly related to environmental variables for sponges and foraminifera, and primarily for mushroom corals and sea urchins. The lack of a pure spatial component suggests that these taxa may not be dispersal limited within the spatial scales of this study (c. 1600 km²). The analyses of the corals and foraminifera were additionally tested at two spatial scales of sampling. Both taxa were primarily associated with local‐scale environmental variables at the local scale and larger‐scale variables at the larger scale. Mean inter‐plot similarity was also higher and variation lower at the larger scale. The results suggest that substantial variation in similarity can be predicted using simple locally assessed environmental variables combined with remotely sensed parameters.     

Pockmark-like depressions near the Goliat hydrocarbon field,Barents Sea: Morphology and genesis

Pockmarks are observed worldwide along the continental margins and are inferred to be indicators of fluid expulsion. In the present study, we have analysed multibeam bathymetry and 2D/3D seismic data from the south-western Barents Sea, in relation to gas hydrate stability field and sediment type, to examine pockmark genesis. Seismic attributes of the sediments at and beneath the seafloor have been analysed to study the factors related to pockmark formation. The seabed depths in the study area are just outside the methane hydrate stability field, but the presence of higher order hydrocarbon gases such as ethane and/or propane in the expelled fluids may cause localised gas hydrate formation. The selective occurrence of pockmarks in regions of specific seabed sediment types indicates that their formation is more closely related to the type of seabed sediment than the source path of fluid venting such as faults. The presence of high acoustic backscatter amplitudes at the centre of the pockmarks indicates harder/coarser sediments, likely linked to removal of soft material. The pockmarks show high seismic reflection amplitudes along their fringes indicating deposition of carbonates precipitated from upwelling fluids. High seismic amplitude gas anomalies underlying the region away from the pockmarks indicate active fluid flow from hydrocarbon source rocks beneath, which is blocked by overlying less permeable formations. In areas of consolidated sediments, the upward flow is limited to open fault locations, while soft sediment areas allow diffused flow of fluids and hence formation of pockmarks over a wider region, through removal of fine-grained material.     

Change in coral reef benthic communities in the Lembeh Strait and Likupang, North Sulawesi, Indonesia

Anthropogenic impacts and natural disturbances have been intense recently in the global scale, affecting the composition of coral reef benthic communities from coral to algal dominated reefs. However, this condition does not always occur considering corals are able to recover when the stressors falter. This study aims to investigate the change in coral reef benthic communities and the relationship among benthic categories. The study was carried out in 2014 and 2016 at five sites, three sites in the Lembeh Strait and two sites in Likupang, North Sulawesi Province. Underwater Photo Transect(UPT) was used at depth of around 4–6 m in slope areas. The result indicated that the benthic communities were slightly changing: the percent covers of hard corals, sponges, soft corals, macroalgae and substrate categories were not significantly different between the years but category of others, particularly seasonally growing hydroid, increased significantly, occupying the available substrates and overtopping other benthos surrounding. The study also found that there was a significant relationship between the change in benthic gradient and the number of hard coral colonies: when the composition becomes less complex, the number of colony declines. In contrast, the hard coral diversity remained unchanged, suggesting the coral reefs apparently have an ecological resilience(sustainable species diversity) against the change although ecological complexity declines. In addition, the hard coral cover was significantly correlated with soft coral and sponge covers, which did not change significantly among the years. In general, the coral reefs in North Sulawesi might experience a temporary blip due to the increasing percent cover of others, and be predicted to recover as there was no indication of soft corals and sponges to increase significantly. However, it is necessary to investigate the dynamic of benthic communities in different depth gradients to gain a comprehensive understanding as the communities respond differently to the light intensity.     

Community structure of zooplankton in the Lembeh Strait, Bitung, and Wori Beach, Manado, North Sulawesi, Indonesia

The community structure of zooplankton has been conducted in the Lembeh Strait in Bitung and Wori Beach in Manado, North Sulawesi in October 2015. Sampling of this research was conducted in 22 sampling sites along the strait. Zooplankton samples were collected from 22 stations, by NORPAC 300 μm net that was vertically hauled from maximum 10 m depth up to the surface water. The samples were poured into the bottle with formalin of 4%as preservative. The results showed that there were 43 taxa of zooplankton. The abundance of zooplankton was between 21.216–4 193.776 ind./m~3. The dominant taxa were copepod, especially Calanoida. The composition of zooplankton was relatively similar in all stations. We showed the abundance, dominance, composition and distribution of zooplankton at this research. More extensive studies concerning zooplankton is required to understand zooplankton biodiversity as a whole especially on the geographical and spatial distribution to describe population and community dynamic in the Lembeh Strait and Wori Beach.     

Neogene stratigraphy and the sedimentary and oceanographic development of the NW European Atlantic margin

A regional correlation of Neogene stratigraphy has been attempted along and across the NW European Atlantic continental margin, between Mid-Norway and SW Ireland. Two unconformity-bounded successions are recognised. These are referred to as the lower and upper Neogene successions, and have been dated as Miocene–early Pliocene and early Pliocene–Holocene, respectively, in age. Their development is interpreted to reflect plate-wide, tectonically driven changes in the sedimentary, oceanographic and latterly climatic evolution of the NE Atlantic region. The lower Neogene succession mainly preserves a record of deep-water sedimentation that indicates an expansion of contourite sediment drifts above submarine unconformities, within this succession, on both sides of the eastern Greenland–Scotland Ridge from the mid-Miocene. This is interpreted to record enhanced deep-water exchange through the Faroe Conduit (deepest part of the Southern Gateway), and can be linked to compressive inversion of the Wyville–Thomson Ridge Complex. Thus, a pervasive, interconnected Arctic–North Atlantic deep-water circulation system is a Neogene phenomenon. The upper Neogene succession records a regional change, at about 4 Ma, in the patterns of contourite sedimentation (submarine erosion, new depocentres) coeval with the onset of rapid seaward-progradation of the continental margin by up to 100 km. This build-out of the shelf and slope is inferred to record a marked increase in sediment supply in response to uplift and tilting of the continental margin. Associated changes in deep-water circulation may be part of an Atlantic-wide reorganisation of ocean bottom currents. Glacial sediments form a major component of the prograding shelf margin (shelf-slope) sediment wedges, but stratigraphic data indicate that the onset of progradation pre-dates significant high-latitude glaciation by at least 1 Ma, and expansive Northern Hemisphere glaciation by at least 3 Ma.     

蓬莱19—3地区新近系物源分析及应用

鉴于蓬莱19—3地区物源存在一定的分歧,通过对蓬莱19—3地区新近系砂岩碎屑轻矿物、重矿物、粒度分析、砂岩展布特征、地震资料及动态资料的分析认为该地区物源主要来自于东边。结合物源及藻类分析认为蓬莱19—3以西存在一定的水体,明下段表现出浅水三角洲窄河道绫罗分布的特征,而馆陶组以辫状三角洲平原为主。建议在油田地质油藏研究过程中考虑物源及沉积相,完善产液结构,从而改善油田开发效果。