苏丹迈努特盆地油气成藏机理和成藏模式

苏丹迈努特盆地是中国石油天然气集团公司在海外最大的勘探项目．快速高效发现大油田是跨国勘探的主要目的。本文在过去三年的石油地质综合研究和勘探的基础上,系统总结盆地的独特石油地质特征和油气聚集规律。迈努特盆地三期裂谷的叠置．早白垩世是最主要的一期,形成了主力烃源岩;晚白垩世弱裂谷期,沉积了一套以砂岩为主的地层;古近纪又发育一期裂谷．是主力成藏组合发育时期。特定的构造—地层特征和演化史,决定了盆地独特的油气成藏机理和成藏模式——跨时代油气聚集模式。这一模式的建立为最终发明储量达5亿吨的大油田提供了理论基础。     

The Neogene Fohnsdorf Basin: basin formation and basin inversion during lateral extrusion in the Eastern Alps (Austria)

The evolution of the early/middle Miocene Fohnsdorf Basin has been studied using borehole data, reflection seismic lines, and vitrinite reflectance. The basin is located along the sinistral Mur-Mürz fault system and probably formed as an asymmetric pull-apart basin, which was subsequently modified by halfgraben tectonics, as a consequence of eastward lateral extrusion. Sedimentation started with the deposition of fluvio-deltaic sediments. Thick coal accumulated in the northwestern basin. Thereafter subsidence rates increased dramatically with the formation of a lake several hundred meters deep. The lake was filled mainly from the north with more than 1500?m of sediments showing a coarsening-upward trend due to southward prograding deltaic lobes. A sequence of more than 1000?m of boulder gravels (Blockschotter) in the southeastern part of the basin are interpreted as the upper part of a coarse-grained fan delta succession, which accumulated along a normal fault along the southern basin margin. Fan deltas reached the central basin only during the early stages of sedimentation and during the late stages of basin formation. Miocene heat flow was approximately 65–70?mW/m², which is significantly lower than in other basins along the Mur-Mürz fault system. The present-day southwestern basin margin is a recent feature, which is related to transpression along the dextral Pöls-Lavanttal fault system. It is formed by reverse faults constituting the northeastern part of a flower structure. Miocene sediments in the Feeberg valley are preserved along its southwestern part. Uplift of the central part of the flower structure was at least 2.4?km. North–south compression resulted in the deformation of the basin fill, uplift of the E/W-trending basement ridge separating the Fohnsdorf and Seckau basins, and in the erosion of 1750?m of sediments along the northern basin margin.     

Variability of the metal content of flood deposits

Fresh flood deposits were sampled in the flood-plains of two river systems, the River Meuse, with a catchment area of 33,000 km² and the River Geul, with a catchment area of 3,000 km². As a result of industrial and mining activities, both rivers have a history of severe metal pollution, especially with zinc, lead, and cadmium. The flood deposits of both rivers are heterogeneous mixtures of contaminated bottom sediments (with relatively long residence times in the river) and clean sediments derived from soil erosion on agricultural cropland (with very short residence times). An additional source of sediment is formed by erosion of older, locally highly contaminated streambank deposits. These older sediments are polluted as a result of solid waste disposal containing metalliferous ore and tailings in the sand fraction. This is especially the case in the River Geul, which drains an old zinc and lead mining area. The metal content of the Meuse sediments, however, originates largely from liquid industrial wastes and occurs mainly in the clay fraction. For this reason, the positive correlation between textural composition, organic matter content, and heavy metal concentration, which is often reported, was not observed, and normalization of the metal content was not possible. Nevertheless, a clear decrease of contamination was noticed along the River Geul; this trend was absent along the River Meuse. An attempt has been made to model the longitudinal decay pattern for each of the investigated havey metals.     

Cenozoic volcanism,tectonism and stream derangement in the Snowy Mountains and northern Monaro of New South Wales

Studies of Cenozoic lavas and associated sediments in the Kiandra‐Cabramurra and Adaminaby‐Cooma areas identify and date tectonic deformations responsible for differential uplift and drainage development of the region. Volcanic activity on the northern Monaro was mainly Eocene‐Oligocene but in the extreme north there are Early Miocene sediments and lavas. Volcanic activity and folding began to rearrange the drainage in the Eocene‐Oligocene. The headwaters of the Murrumbidgee River originally flowed south into the Eucumbene River but Early Miocene folding and faulting uplifted the Monaro Range and created a large lake near Adaminaby. Lake overtopping rerouted the drainage east and then south along the basalt‐filled valley of an old north‐flowing tributary, the ‘Adaminaby River’, forming the present‐day Murrumbidgee River. The folding also produced a 300 m height difference between the Berridale and Adaminaby Plateaus and formed a section of the Great Divide. This fold displacement ranks with the largest Cenozoic fault displacements. In the Kiandra area tectonism associated with Early Miocene volcanism rearranged the drainage and tilted the Kiandra area and Kosciuszko Block to the north.     

Submerged caves of Croatia: distribution,classification and origin

Presently, 235 submerged caves and pits have been recorded along the Croatian coast and islands, partly or completely submerged by sea water. Contrary to the inland situation, recorded submerged features are predominantly horizontal (60%), though there are indications that the real situation is similar to that of the continental part where 69% are vertical pits. Completely marine conditions are established in 126 caves and the rest are anchihaline caves and submarine springs. Speleothems are found in more than 140 caves. By their origin, the investigated caves are all continental features formed in Mesozoic and Palaeogene carbonates, subsequently submerged owing to sea transgression. Due to the relatively low wave energy, rapid sea level rise and maturity of the host rock, they do not fit into concepts of a sea cave or a flank margin cave development, but they fulfil several conditions for being the blue holes. Since the term ‘blue hole’ is mainly associated with the Bahamian karst, our attempt is only to show the possible similarities with no intention of ascribing that term to the Croatian caves. Beside karstological issues, Croatian submerged caves are unique environmental, archaeological and tourism assets.     

Lithification of some modern carbonate sediments in a hypersaline lake adjacent to the Black Sea

In the hypersaline Techirghiol Lake adjacent to the Black Sea, sporadically formed lithified blocks and grapestone are found which are the result of cementation of carbonate sediments with aragonite and possibly kutnahorite (manganesian calcite). The lithified blocks are characterized by a central cavity bordered by a lithified envelope. The formation of the carbonate cement is due to subaquatic bacterial processes of calcium sulfate reduction and the synthesis of calcium carbonate at the expense of gypsum concretions derived from Pleistocene red clays cropping out along the shore of the lake. These lithified blocks have geological significance as they may be usable as criteria for the recognition of sediments deposited in the past near to the shores of hypersaline lakes.     

弧陆碰撞背景下沉积物轴向与横向搬运转换*

板块俯冲碰撞拼合带是盆山相互作用最为强烈的地区,发育有弧前、弧间及弧后多种类型的盆地,沉积物的剥蚀搬运作用极为活跃。证据显示,沉积物搬运充填过程在构造—古地理控制型盆地中具有一定的演变规律,伴随盆地演化,沉积物轴向搬运与横向搬运呈此消彼长的互动关系。南海南北两侧均发育了大型板块俯冲拼合带及相关的沉积盆地,在盆地发育早期沉积物沿盆地长轴方向分别形成昆莺琼古河和巽他古河,以轴向搬运的方式分别把越南中部及马来半岛沉积物由西向东输送到南海,形成大型三角洲及前三角洲深水扇沉积,河流发育位置均在板块拼合转折地段。在盆地发育的成熟阶段,沉积物以横向搬运的方式进入盆地,与轴向搬运沉积物形成混合堆积。轴向搬运是洋陆碰撞拼合盆地中一种重要的沉积物搬运途径,主要受盆地形成时的构造古地理控制。     

弧陆碰撞背景下沉积物轴向与横向搬运转换*

板块俯冲碰撞拼合带是盆山相互作用最为强烈的地区,发育有弧前、弧间及弧后多种类型的盆地,沉积物的剥蚀搬运作用极为活跃。证据显示,沉积物搬运充填过程在构造—古地理控制型盆地中具有一定的演变规律,伴随盆地演化,沉积物轴向搬运与横向搬运呈此消彼长的互动关系。南海南北两侧均发育了大型板块俯冲拼合带及相关的沉积盆地,在盆地发育早期沉积物沿盆地长轴方向分别形成昆莺琼古河和巽他古河,以轴向搬运的方式分别把越南中部及马来半岛沉积物由西向东输送到南海,形成大型三角洲及前三角洲深水扇沉积,河流发育位置均在板块拼合转折地段。在盆地发育的成熟阶段,沉积物以横向搬运的方式进入盆地,与轴向搬运沉积物形成混合堆积。轴向搬运是洋陆碰撞拼合盆地中一种重要的沉积物搬运途径,主要受盆地形成时的构造古地理控制。     

Flow properties of turbidity currents in Bute Inlet, British Columbia

Bute Inlet, a fiord along the southwestern coast of British Columbia, Canada, includes a sea-floor sedimentation system 70 km in length which resembles those developed on some large submarine fans. Turbidity currents originate at the head of the flord on the submerged delta fronts of the Homathko and Southgate rivers. They move downslope for about 30 km within a single large incised channel, spill onto a depositional area termed the channel lobe complex, and finally spread out over a low-relief distal splay area that passes 55 km downslope into a flat basin floor. During the present study, turbidity currents in Bute Inlet were studied using sea-floor morphology, bottom sediment distribution, and in-situ instrument packages. The mean velocities of the most recent flows, estimated from surface sediment grain size, has varied between 100–120 cm s^–1 in the incised channel, 20–50 cms^–1 in the channel lobe complex, and < 5 cm s^–1 on the basin floor. Velocities based on channel morphology are poorly constrained but are in the range of 160-425 cm s^–1 in the upper part of the incised channel and 66 cm s^–1 in the lower channel. Calculated flow densities range from 1.049 to 1.028g cm^–3. Turbidity flows monitored in 1986 using submerged instrument packages exceeded 32 m in thickness in the upper part of the incised channel, where the maximum measured velocity was 330 cm s^–1. At the head of the channel lobe complex the maximum velocity had declined to 75 cm s^–1. The density of the monitored flows is estimated at 1.025-1.03g cm^–3. The cored sediments and channel morphology yield estimates of mean flow velocities that are generally greater than those measured by the in-situ instrument packages and estimated from modern surface sediments. The former suggest past flow velocities up to 500 cm s^–1 in the incised channel, about 20 cm s^–1 in spillover deposits along the lower part of the incised channel, and 100-140 cm s^–1 in the distal splay. The contrast between the velocities of modern and past flows suggests that past flows may have been considerably larger and more energetic than those presently occurring in Bute Inlet. The size properties of sediments in the monitored turbidity flows suggest a strong vertical size gradient in the suspended load during transport. The surface and cored sediments fine downslope from the channel lobe complex to distal splay area. Distinctive sedimentary sequences are recognized in cores from the spillover lobes, channel lobe complex, distal splay, and basin floor depositional areas. Many individual turbidites grade downslope from massive T_a divisions in the channel lobe complex and probably in the incised channel to T_a divisions overlain by slurried divisions on the distal splay and largely slurried beds on the basin floor. These facies suggest that individual currents commonly evolve from largely cohesionless suspensions in the incised channel and channel lobe complex to dilute cohesive slurries downslope on the distal splay and basin floor. Many flows in Bute Inlet fail to develop a traction state of sedimentation and the resulting turbidites lack well-developed T_b. T_c, and T_d divisions.     

Neotectonics and recent uplift at Kamchatka and Aleutian arc junction, Kamchatka Cape area, NE Russia

The tectonic position of the Kamchatka Cape Peninsula at the junction of the active Kuril–Kamchatka and Aleutian arcs exposes the coastline of the peninsula to strong neotectonic activities. Fracture zones have variable influence on uplift of the Kamchatka Cape Peninsula. Relevant morphologic indicators of neotectonic activity are multilevel, highly uplifted marine terraces and terraces displaced along active faults. Recent uplift rates of coastal sediments are determined by remote sensing via ASTER and SRTM DEM combined with optically stimulated luminescence dating (OSL). On the Kamchatka Cape Peninsula, terraces from the same generation are mapped at different elevations by remote sensing methods. After defining different areas of uplifted terraces, four neotectonic blocks are identified. According to apatite fission track data, the mean differential exhumation rates range from 0.2 to 1.2 mm year^?1 across the blocks since Late Miocene. The OSL data presented point to significant higher uplift rates of up to 3 ± 0.5 and 4.3 ± 1 mm year^?1, which indicates an acceleration of the vertical movement along the coast of Kamchatka Cape Peninsula in Upper Pleistocene and Holocene times.     

珠江口盆地白云凹陷恩平组物源转换及沉积充填演化

为了阐明白云凹陷古近系恩平组的物源供给方式及沉积充填演化规律,以古地貌-古生物分析、LA-ICPMS锆石U-Pb定年、地震属性分析及典型地震相识别为主要技术手段,对白云凹陷恩平组不同沉积时期的沉积环境、古地貌特征、锆石形态及年代组成、砂体发育特征等进行分析,认为恩平组沉积时期其物源供给方式及沉积充填特征发生了明显的变化.恩平组SQ1~SQ2时期陆相断陷湖盆特征明显,沉积时期沉积范围较小,以盆内短程物源（中生代火成岩基底母岩）供给为主:南部陡坡带主要发育近源快速堆积而成的扇三角洲;北部缓坡带发育充填结构典型的辫状河三角洲及上倾尖灭明显的滩坝砂体.恩平组SQ3时期主要为半封闭的海湾沉积环境,沉积范围较大,以盆外远程物源（华南褶皱带前寒武纪-古生代变质岩基底母岩）供给为主:南部陡坡带断裂活动减弱,发育规模较小的扇三角洲;北部缓坡带发育沿北西-南东方向展布的三期前积反射并不断向盆地中心进积的典型大型辫状河三角洲.      

中国西北干旱区湖泊沉积物中有机质碳同位素组成的环境意义--以民勤盆地三角城古湖泊为例

通过对中国西北干旱区石羊河流域民勤盆地三角城古湖泊沉积物有机质碳同位素组成(^δ13Corg)分析,表明末次冰期与全新世时气候和植被有明显的差异,末次冰期^δ13Corg总体偏轻(-30‰～-25‰),而全新世碳同位素组成则有较大的变化,在早全新世碳同位素组成有多次短期快速变重(-10‰左右)的变化,中全新世碳同位素组成总体偏重(-20‰～-10‰),晚全新世碳同位素组成偏轻(-25‰左右)。分析表明湖泊沉积物有机质碳同位素组成反映了陆生C₃植物和湖泊内源水生植物变化的关系,末次冰期以来西北干旱区C₄植物不发育,偏重的有机质碳同位素值与C₄植物无关。从沉积物中有机质组分、元素等分析表明,末次冰期时主要以河流相沉积为主,湖泊中有机质主要来源于上游祁连山的陆生C₃植物,有机碳含量较低,表明当时的上游的陆生植被不繁盛,区域气候较干冷;从全新世开始,三角城古湖泊开始形成,沉积物中碳同位素组成偏重的有机质主要来源于湖泊中的沉水植物,此时湖泊水体较大,湖泊生产力较高。而沉积物中有机质碳同位素组成偏轻时期的有机质主要来源于挺水植物、陆生C₃植物,较低的有机碳含量说明该时期陆生植被不发育,气候较干冷,湖泊水体较小     

P–T path of high-pressure/low-temperature rocks and tectonic implications in the western Tianshan Mountains, NW China

The Chinese western Tianshan high-pressure/low-temperature (HP–LT) metamorphic belt, which extends for about 200 km along the South Central Tianshan suture zone, is composed of mainly metabasic blueschists, eclogites and greenschist facies rocks. The metabasic blueschists occur as small discrete blocks, lenses, bands, laminae or thick beds in meta-sedimentary greenschist facies country rocks. Eclogites are intercalated within blueschist layers as lenses, laminae, thick beds or large massive blocks (up to 2 km² in plan view). Metabasic blueschists consist of mainly garnet, sodic amphibole, phengite, paragonite, clinozoisite, epidote, chlorite, albite, accessory titanite and ilmenite. Eclogites are predominantly composed of garnet, omphacite, sodic–calcic amphibole, clinozoisite, phengite, paragonite, quartz with accessory minerals such as rutile, titanite, ilmenite, calcite and apatite. Garnet in eclogite has a composition of 53–79 mol% almandine, 8.5–30 mol% grossular, 5–24 mol% pyrope and 0.6–13 mol% spessartine. Garnet in blueschists shows similar composition. Sodic amphiboles include glaucophane, ferro-glaucophane and crossite, whereas the sodic–calcic amphiboles mainly comprise barroisite and winchite. The jadeite content of omphacite varies from 35–54 mol%. Peak eclogite facies temperatures are estimated as 480–580 °C for a pressure range of 14–21 kbar. The conditions of pre-peak, epidote–blueschist facies metamorphism are estimated to be 350–450 °C and 8–12 kbar. All rock types have experienced a clockwise P–T path through pre-peak lawsonite/epidote-blueschist to eclogite facies conditions. The retrograde part of the P–T path is represented by the transition of epidote-blueschist to greenschist facies conditions. The P–T path indicates that the high-pressure rocks formed in a B-type subduction zone along the northern margin of the Palaeozoic South Tianshan ocean between the Tarim and Yili-central Tianshan plates.     

Sr-Isotope record of Quaternary marine terraces on the California coast and off Hawaii

Strontium-isotopic ratios of dated corals have been obtained from submerged reefs formed during Quaternary glacial periods off the Hawaiian islands. These data, combined with data from deep-sea sediments, tightly constrain the secular variation of marine ⁸⁷Sr/⁸⁶Sr for the past 800,000 yr. Although long-term trends are apparent, no significant (>0.02‰), rapid (<100,000 yr) excursions in ⁸⁷Sr/⁸⁶Sr were resolved nor did we observe any samples with ⁸⁷Sr/⁸⁶Sr greater than that of modern seawater. Strontium in mollusks from elevated marine terraces formed during interglacial periods on the southern California coast show resolvable and consistent variations in ⁸⁷Sr/⁸⁶Sr which, when compared to the trend of Quaternary marine ⁸⁷Sr/⁸⁶Sr, can be used to infer uplift rates and define approximate ages for the higher terraces. The Sr-isotope age estimates indicate that uplift rates vary among crustal blocks and were not necessarily constant with time. No contrast in Sr-isotopic ratios between similar-age Hawaiian and California fossils was observed, confirming that any change in marine ⁸⁷Sr/⁸⁶Sr from glacial to interglacial periods must be small. A realistic appraisal of the potential of Sr-isotope stratigraphy for chronometric applications in the Quaternary suggests that the technique will be limited to relatively coarse distinctions in age.     

琼东南盆地松南低凸起花岗岩年代学、地球化学特征及构造环境

为了探讨琼东南盆地松南低凸起花岗岩的岩石成因及构造环境,本文对其进行了岩相学、锆石年代学与地球化学研究。研究结果显示：潜山岩性主要为花岗闪长岩和二长花岗岩;花岗闪长岩和二长花岗岩LAICPMS锆石UPb定年结果分别为228.6和243.7 Ma,为三叠纪岩浆活动产物;岩体属于高钾钙碱性系列,具有高硅（w（SiO2)为54.94%~79.71%）,中等质量分数的碱（w（K2O+Na2O）为3.53%~6.43%）、铝（w（Al2O3）为9.82%~18.23%）、钙（w（CaO）为1.24%~9.55%）和镁（w（MgO）为0.37%~2.28%）的特征;铝饱和指数（A/CNK）为1.09~2.13,兼有准铝质和过铝质花岗岩;岩石整体富集K、Rb、Th等大离子亲石元素,亏损 Ta、Nb、Ti 等高场强元素,中等—弱的Eu负异常（δEu为0.50~0.85）。岩相学和地球化学特征显示花岗闪长岩为准铝质I型花岗岩、二长花岗岩为过铝质S型花岗岩,形成于壳内沉积物的部分熔融。综合分析认为该花岗岩具有后碰撞花岗岩的特征,形成于伸展构造环境,与华南、印支块体碰撞后的反向伸展作用有关。     

Seismogeological analysis of the pre-Jurassic sediment complexes of the South Kara syneclise in connection with the tectonic zoning of the sedimentary cover

We present new data on the structure of deep horizons of the sedimentary cover of the South Kara syneclise, based on an integrated interpretation of data from modern seismic prospecting and data on the geologic structure of the adjacent folded areas. A network of seismic base profiles reprocessed with up-to-date programs is used to determine the structure of the wave fields of the pre-Jurassic sediments of the South Kara syneclise. The interpretation of the wave fields with the use of the network of seismic base profiles shows that the wave fields of the Pai-Khoi-Novaya Zemlya monoclise and the Novaya Zemlya-Taimyr terrace are fundamentally different from those of the South Kara central area of depressions and uplifts. We substantiate a new structural and tectonic zonation of the northern West Siberian Plate, with areas of Hercynian and Early Cimmerian consolidation. The geologic evolution of the South Kara syneclise and adjacent areas in the Late Paleozoic-Early Jurassic is considered. The studies show that the Hercynides of the northern Taimyr Peninsula occupy the deepest central part of the South Kara syneclise, including the North Siberian step. They are separated from the coeval sediments of the surface part of the northern West Siberian Plate by the Early Cimmerian folded area of the Yamal-Pai-Khoi saddle, which joins the Early Cimmerian West Taimyr folded area to the Early Cimmerides of Pai-Khoi and Novaya Zemlya.The Permo-Triassic rifts distinguished in central West Siberia have no shelf extension. Areal structural studies along the surface of the acoustic basement and analysis of wave fields showed that the structures of the South Kara syneclise were semiconcentric and concentric intermontane depressions and troughs in the Permian and Lower-Middle Triassic. They formed at the orogenic stage of evolution of the Hercynides. In the Devonian-Carboniferous, the South Kara syneclise was an intracontinental block structure. It is presumed that elevated blocks consist of carbonate sediments, whereas the separating troughs consist of bathyal terrigenous sediments. The Hercynian folding, which affected mainly deep-water sediment complexes, was followed by an inversion of the troughs, their uplifting and disintegration. The intermontane depressions which formed instead of carbonate shelf in the Permian were filled with sediments from the uplifts which formed instead of the troughs.A well-grounded conclusion is made about the hydrocarbon potential of the pre-Jurassic basement of the South Kara syneclise. The layered seismic record of the pre-Jurassic sediments suggests their heterogeneous composition, i.e., the presence of sand and clay series (reservoirs and caps). The pools might be of the arch-bedded and lithologic (traps which formed in the case of the toplap of beds onto the eroded surface) types or be localized along the line of pinching-out of the Triassic sediments. The largest number of Paleozoic structures is concentrated on the Rogozinskii and Vilkitsky arches, in the Monskaya and Matusevich saddles, and in the northern Rusanov-Skuratov arch.© 2014, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.     

四川攀枝花昔格达组下伏砾石层成因和时代探讨与古金沙江河谷发育

本文主要描述和讨论了四川省攀枝花市沿金沙江分布、并以炳草岗地龙箐剖面为代表的昔格达组湖相沉积下伏的砾石层的沉积特征及其河流相成因.根据前人对昔格达组湖相沉积的磁性地层学研究结果,为4.2/3.28～2.6/2.12/1.78 MaBP的上新世中、晚期或至早更新世早期,表明其下伏厚达50 m的砾石层的形成时代约为4.2～4.5/5 MaBP的上新世早期.早上新世金沙江河流相砾石层在接近金沙江谷底位置的发现,表明金沙江很早就已经从青藏高原主夷平面下切了2000 m以上、已在接近其现今谷底的位置上存在.这对于探讨古金沙江的河谷发育及其与青藏高原隆升的关系,具有重要的指示意义.     

Geochemical Characteristics and Tectonic Setting of the Laohushan Basalts, North Qilian Mountains

The Ordovician Laohushan ophiolite, located in the eastern part of the North Qilian Mountains, is mainly composed of meta-peridotites, gabbros and basalts alternating with sediments. The sediments are mainly turbidites, including sandstones, siltstones, cherts etc. Major elements show that the basalts are subalkaline tholeiites and may be analogous to ocean-floor basalts. Except a few N-MORBs, most of the basalts are E-MORBs as indicated by incompatible element ratios such as (La/Ce)N, La/Sm, Ce/Zr, Zr/Y and Zr/Nb. Negative Nb anomaly is common but negative Zr, Hf and Ti anomalies are quite rare. Based on the geochemical characteristics, it is suggested that the Laohushan basalts were formed in a back-arc basin. εNd (t) of the basalts ranges between +3.0 and +8.9 and (87Sr/86Sr), ranges between 0.7030 and 0.7060, indicating a depleted mantle source which was mixed with more or less enriched mantle components. Furthermore, the petrography of the sandstones and geochemistry of the cherts suggest that the     

埕岛—桩海地区潜山滑脱构造与油气聚集

运用三维地震、钻井资料,揭示了埕岛-桩海地区古生界与太古宇接触面滑脱构造基本特征及形成机理,剖析了其在油气勘探中的作用。主滑脱面为下古生界与太古宇之间的不整合面,表现为沿不整合面发育多条叠瓦状排列上陡下缓的低角度滑脱断层,倾末端收敛于不整合面,并未切穿下伏太古宇地层,致使滑脱断层切割形成的不同块体地层发生明显的翘倾旋转或缺失。平面上自西向东,滑脱强度、滑脱距离存在明显差异,西部滑脱作用强度最大,滑脱距离最远,导致下古生界地层严重缺失,中生界地层直接不整合覆盖于太古宇基底之上;中部滑脱作用活动强烈,滑脱距离较远,古生界潜山表现为一系列类似“飞来峰”的三角形残丘形态;东段滑脱作用活动较弱,古生界潜山被分割成一系列反向断块,各个断块地层保存相对较完整。综合分析表明,研究区潜山滑脱运动主要发生在郯庐断裂左旋走滑向右旋走滑的转换时期;滑脱作用改善了潜山储层物性,主滑脱面、滑脱断层与主油源断层共同构成了本区立体输导网络,为该区整体含油连片提供了有利条件。     

Middle and late Pleistocene glaciations in the Campo Felice Basin (central Apennines, Italy)

The present paper refers to research conducted in the tectonic-karst depression of Campo Felice in the central Apennines (Italy), in which glacial, alluvial and lacustrine sediments have been preserved. Stratigraphic interpretations of sediments underlying the Campo Felice Plain are based on evidence obtained from nine continuous-core boreholes. The boreholes reach a depth of 120 m and provide evidence of five sedimentation cycles separated by erosion surfaces. Each cycle is interpreted as an initial response to a mainly warm stage, characterized by low-energy alluvial and colluvial deposition, pedogenesis, and limited episodes of marsh formation. In turn, a mainly cold stage follows during which a lake formed, and glaciers developed and expanded, leading to deposition of glacial and fluvioglacial deposits. The chronological framework is established by eleven accelerator mass spectrometer ¹⁴C ages and three ³⁹Ar-⁴⁰Ar ages on leucites from interbedded tephra layers. These age determinations indicate five glacial advances that respectively occurred during marine oxygen isotope stages 2, 3-4, 6, 10 and 14.