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1.
Numerous geophysical investigations in the western part of onshore Denmark constitute the basis for a delineation of buried Quaternary valleys. The geophysical methods comprise primarily Transient ElectroMagnetic (TEM) and reflection seismic surveys, and the geophysical data have been combined with lithological data from boreholes. Buried valleys appear both as single valleys and in dense networks. The internal structure of the valleys is typically complex due to repeated erosional and depositional events. Buried valleys are common geological structures in the region and they influence the distribution of Tertiary and Quaternary sediments greatly. A large number of buried valleys in the region contain important aquifers, whose natural protection varies depending on thickness and character of overlying clay layers. Many of these aquifers are deep-seated and well protected, but because of the prevailing heterogeneity of the valley infill and the erosional incisions created by different valley generations, preferential flow paths for downward transport of contaminated water from shallow aquifers may occur. 相似文献
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Buried Quaternary valleys in Denmark are complex structures filled with various deposits consisting primarily of glacio-lacustrine clay, till and meltwater sand, and gravel. The valleys are important geophysical targets, because they often contain significant volumes of groundwater used for public water supply. About 700 km of buried valley structures have been imaged in the western part of Denmark by the transient electromagnetic (TEM) method. The ability to map the valleys depends primarily on valley geometry, infill architecture and the resistivity of the fill sediments as well as the substratum. One-dimensional (1-D) inversion models of the TEM soundings have been used to construct contour maps of 20 m average resistivities and depth to a good conductor, which provide images for geological interpretation. Images of buried valley morphology, fill properties, infill architecture, such as cut-and-fill structures, valley distribution and valley generations, are characterized for case studies from Hornsyld, Holstebro and the Vonsild/Agtrup areas of Denmark. 相似文献
4.
Jane E. Denne Harold L. Yarger P. Allen Macfarlane Ralph W. Knapp Marios A. Sophocleous James R. Lucas Don W. Steeples 《Ground water》1984,22(1):56-65
Aquifers found in glacial buried valleys are a major source of good-quality ground water in northeastern Kansas. The extent and character of many of these deposits are not precisely known, so a detailed study of the buried valleys was undertaken. Test drilling, Landsat imagery, shallow-earth temperature measurements, seismic refraction, surface electrical resistivity, and gravity data were used to evaluate two sites in Nemaha and Jefferson Counties. Tonal patterns on springtime Landsat imagery and winter/summer anomalies in shallow-earth temperatures were quick and inexpensive methods for locating some glacial buried aquifers and suggested areas for more intensive field studies. Reversed seismic refraction and resistivity surveys were generally reliable indicators of the presence or absence of glacial buried valleys, with most depth determinations being within 25% of test-drilling results. The effectiveness of expensive test-hole drilling was greatly increased by integrating remote sensing, shallow-earth temperature, seismic, and resistivity techniques in the two buried valley test areas. A gravity profile allowed precise definition of the extent of one of the channels after the other techniques had been used for general information. 相似文献
5.
Geophysical investigation of buried Pleistocene subglacial valleys in Northern Germany 总被引：1，自引：0，他引：1
Gerald Gabriel Reinhard Kirsch Bernhard Siemon Helga Wiederhold 《Journal of Applied Geophysics》2003,53(4):159
Buried Pleistocene subglacial valleys are extensively used as groundwater reservoirs by waterworks in northern Germany, although little is known about the locations and size of these valleys and the internal structure of the sediment fill. This lack of knowledge about important groundwater reservoirs is a challenge for geophysics.This paper summarizes the geophysical investigation of two buried Pleistocene subglacial valleys in northern Germany—the Ellerbeker Rinne and the Bremerhaven–Cuxhavener Rinne—including seismic, gravity, and airborne electromagnetic (AEM) surveys. Seismic sections show the detailed structure of the paleovalleys. The reliability of interpretation is enhanced by vertical seismic profiles in wells. The maximum depths of the Ellerbeker Rinne and the Bremerhaven–Cuxhavener Rinne were found to be 360 and about 400 m, respectively. Gravity survey revealed Bouguer anomalies above the sediment fill of both buried valleys. The Ellerbeker Rinne produces a negative residual anomaly of −0.5 mGal, whereas the sediments of the Bremerhaven–Cuxhavener Rinne produce a positive anomaly. The latter one is superimposed by negative gravity anomalies due to near-surface structures. The Bremerhaven–Cuxhavener Rinne can be mapped by airborne electromagnetics at locations without saltwater intrusion, which would affect the measurements. The electrical conductivity of the clay layer at the top of the valley fill differs significantly from that of the surrounding sand. The combined use of these three geophysical methods, which measure different physical parameters, leads to a better understanding of the subsurface geology and the hydrogeology of the Pleistocene subglacial valleys. 相似文献
6.
《中国科学:地球科学(英文版)》2015,(6)
The Dongsha submarine canyon is a large canyon belonging to a group of canyons on the northeastern South China Sea margin. Investigation of the Dongsha canyon is important for understanding the origin of this canyon group as well as the transport mechanism of sediments on the margin, and the evolution of the Taixinan foreland basin and the associated Taiwan orogenic belt. In this study, the morphology, sedimentary characteristics, and origin of the Dongsha canyon were investigated by integrating high-resolution multi-channel seismic reflection profiles and high-precision multibeam bathymetric data. This is a slope-confined canyon that originates in the upper slope east of the Dongsha Islands, extends downslope in the SEE direction, and finally merges with the South Taiwan Shoal canyon at a water depth of 3000 m. The total length and average width of the canyon are around 190 and 10 km, respectively. Eleven seismic sequence boundaries within the canyon fills were identified and interpreted as incision surfaces of the canyon. In the canyon fills, four types of seismic facies were defined: parallel onlap fill, chaotic fill, mounded divergent facies, and migrated wavy facies. The parallel onlap fill facies is interpreted as alternating coarser turbidites or other gravity-flow deposits and fine hemipelagic sediments filling the canyon valley. The chaotic fill facies is presumed to be debrites and/or basal lag deposits filling the thalwegs. The mounded divergent and migrated wavy seismic facies can be explained as canyon levees consisting mainly of overspilled fine turbidites and sediment waves on the levees or on the canyon-mouth submarine fans. Age correlation between the sequence boundaries and the ODP Site 1144 data suggests that the Dongsha canyon was initiated at approximately 0.9 Ma in the middle Pleistocene. Mapping of the canyon indicates that the canyon originated at the upstream portion of the middle reach of the modern canyon, and has been continuously expanding both upstream and downstream by retrogressive erosion, incision, and deposition of turbidity currents and other gravity transport processes. The ages of the sequence boundaries representing major canyon incision events are in good agreement with those of global sea-level lowstands, indicating that sea-level changes may have played an important role in the canyon's development. The Dongsha canyon developed in a region with an active tectonic background characterized by the Taiwan uplifting and the development of the Taixinan foreland basin. However, no evidence suggests that the canyon formation is directly associated with local or regional faulting and magmatic activities. Turbidity currents and other gravity transport processes(including submarine slides and slumps) may have had an important influence on the formation and evolution of the canyon. 相似文献
7.
Radar surveys of Bench Glacier, Alaska, collected over five field seasons between 2002 and 2006 reveal a surface layer of radar transparent ice in this temperate valley glacier. The transparent layer covers the up‐glacier half of the ablation zone and is defined by a distinct lack of the radar scattering events considered typical of temperate ice. Radar scattering ice underlies the transparent zone, and extends to the surface elsewhere on the glacier. We observed the layering in constant offset radar surveys conducted with characteristic frequencies ranging from 5 MHz to 100 MHz. The radar transparent layer extends from the surface to 20 m depth on average, but up to 50 m in some places. Bench Glacier's transparent layer appears similar to the cold surface layer of polythermal glaciers, however, observations in over 50 boreholes on Bench Glacier suggest there is no cold ice corresponding to the radar transparent layer. We conclude that spatially extensive radar‐transparent layers normally used to identify cold ice in polythermal glaciers are present in some temperate glaciers. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
8.
Adnan Ahmad Khan Asam Farid Gulraiz Akhter Khyzer Munir James Small Zulfiqar Ahmad 《Surveys in Geophysics》2016,37(3):579-599
The study describes a methodology used to integrate legacy resistivity data with limited geological data in order to build three-dimensional models of the near subsurface. Variogram analysis and inversion techniques more typically found in the petroleum industry are applied to a set of 1D resistivity data taken from electrical surveys conducted in the 1980s. Through careful integration with limited geological data collected from boreholes and outcrops, the resultant model can be visualized in three dimensions to depict alluvium layers as lithological and structural units within the bedrock. By tuning the variogram parameters to account for directionality, it is possible to visualize the individual lithofacies and geomorphological features in the subsurface. In this study, an electrical resistivity data set collected as part of a groundwater study in an area of the Peshawar basin in Pakistan has been re-examined. Additional lithological logs from boreholes throughout the area have been combined with local outcrop information to calibrate the data. Tectonic activity during the Himalayan orogeny has caused uplift in the area and generated significant faulting in the bedrock resulting in the formation of depressions which are identified by low resistivity values representing clays. Paleo-streams have reworked these clays which have been eroded and replaced by gravel–sand facies along paleo-channels. It is concluded that the sediments have been deposited as prograding fan-shaped bodies and lacustrine deposits with interlayered gravel–sand and clay–silt facies. The Naranji area aquifer system has thus been formed as a result of local tectonic activity with fluvial erosion and deposition and is characterized by coarse sediments with high electrical resistivities. 相似文献
9.
The so called “valley effect” relates to the typical seismic response of basin shaped bedrock filled by quaternary sediments. It is an aspect of the renown “local seismic effect” that shall be taken into account when dealing with microzoning studies. Several experimental surveys and numerical simulations performed worldwide over the last 40 years, confirmed that valley responses under seismic excitations show common features in various geological contexts as far as the sedimentary valleys (e.g. alluvial and lacustrine plains), the intermountain valleys (e.g. alpine valleys) and graben shaped basins. Such features mainly depend on the basin geometry, referred to as the shape ratio SR, and the sediment and basin impedance contrast IC. Although researchers agree on the prominent role of local seismic effects for interpreting erratic damages caused by seismic shaking in urbanized areas, no fully shared strategies have been identified for taking into account valley effect within microzoning studies. In this paper, a numerical simulations on three models of trapezoidal shaped basins have been performed. These valley models relate to sediments and basins detected within the Tuscany Region territory during the VEL project. Results, in terms of the amplification index $\text{ F }_{\mathrm{A}}$ F A have been provided. Three “valley effect charts” for various SR and IC values have been propose for taking into account the local seismic effects due to the basin amplifications within microzoning maps. 相似文献
10.
Christopher F. Waythomas 《Bulletin of Volcanology》1999,61(3):141-161
Akutan Volcano is one of the most active volcanoes in the Aleutian arc, but until recently little was known about its history
and eruptive character. Following a brief but sustained period of intense seismic activity in March 1996, the Alaska Volcano
Observatory began investigating the geology of the volcano and evaluating potential volcanic hazards that could affect residents
of Akutan Island. During these studies new information was obtained about the Holocene eruptive history of the volcano on
the basis of stratigraphic studies of volcaniclastic deposits and radiocarbon dating of associated buried soils and peat.
A black, scoria-bearing, lapilli tephra, informally named the "Akutan tephra," is up to 2 m thick and is found over most of
the island, primarily east of the volcano summit. Six radiocarbon ages on the humic fraction of soil A-horizons beneath the
tephra indicate that the Akutan tephra was erupted approximately 1611 years B.P. At several locations the Akutan tephra is
within a conformable stratigraphic sequence of pyroclastic-flow and lahar deposits that are all part of the same eruptive
sequence. The thickness, widespread distribution, and conformable stratigraphic association with overlying pyroclastic-flow
and lahar deposits indicate that the Akutan tephra likely records a major eruption of Akutan Volcano that may have formed
the present summit caldera. Noncohesive lahar and pyroclastic-flow deposits that predate the Akutan tephra occur in the major
valleys that head on the volcano and are evidence for six to eight earlier Holocene eruptions. These eruptions were strombolian
to subplinian events that generated limited amounts of tephra and small pyroclastic flows that extended only a few kilometers
from the vent. The pyroclastic flows melted snow and ice on the volcano flanks and formed lahars that traveled several kilometers
down broad, formerly glaciated valleys, reaching the coast as thin, watery, hyperconcentrated flows or water floods. Slightly
cohesive lahars in Hot Springs valley and Long valley could have formed from minor flank collapses of hydrothermally altered
volcanic bedrock. These lahars may be unrelated to eruptive activity.
Received: 31 August 1998 / Accepted: 30 January 1999 相似文献
11.
Duricrusts are an important landscape component of the Kalahari region of central southern Africa. Their exposures within the dry valleys (mekgacha) of the Kalahari provide some of the most widespread surface outcrops of the terrestrial Jurassic to Holocene Kalahari Group sediments. Exposures have been extensively used in the construction of lithostrati-graphic sequences, on the assumption that valley systems have incised their courses through a pre-existing duricrust sequence. Recent work, however, has identified the role of groundwater erosion processes in valley development, which may have influenced duricrust formation. Studies of duricrusts from boreholes drilled within two mekgacha show that duricrust type is intrinsically related to the presence of a valley. Analyses of calcretes and silcretes in a series of profiles and thin sections from the Letlhakeng area of Botswana also indicate extensive alteration and diagenesis in association with former higher water tables. Sedimentary sequences within duricrust host materials can be identified but there is no evidence for correlation of duricrust cements between exposures. Profile studies from the Auob Valley in Namibia, however, suggest that this valley has incised through a sequence of duricrusts. Caution is advised in future attempts to correlate duricrust types on the basis of valley exposures, with the recommendation that where such exposures are used in a lithostratigraphic context, only duricrust host material characteristics and not cementing materials should be considered. 相似文献
12.
Modeling multiscale heterogeneity and aquifer interconnectivity 总被引：2，自引：0，他引：2
A number of methods involving indicator geostatistics were combined in a methodology for characterizing and modeling multiscale heterogeneity. The methodology circumvents sources of bias common in data from borehole logs. We applied this methodology to the complex heterogeneity within a regional system of buried valley aquifers, which occurs in the western glaciated plains of North America and includes the Spiritwood Aquifer. The region is conceptualized as having a hierarchical organization with three facies assemblage types (large-scale heterogeneity) and two facies types within each assemblage (small-scale heterogeneity). We statistically characterized the sedimentary architecture at both scales, formulated indicator correlation models from those characterizations, and used the models to simulate the architecture in a multiscale realization. We focused on the interconnectivity of units creating higher-permeability pathways. Higher-permeability pathways span the realization even though the proportion of higher-permeability facies is less than the percolation threshold. Thus, geologic structures as represented in the indicator correlation models create interconnectivity above that which would occur if the higher-permeability facies were randomly placed. This amount of interconnection among higher-permeability facies within the multiscale realization is consistent with that suggested in prior hydraulic and geochemical studies of the regional system. 相似文献
13.
Haim Gvirtzman 《Ground Water Monitoring & Remediation》2013,33(3):101-110
This study deals with the reliability of monitoring the transition zone between fresh and saline waters in coastal aquifers, considering the effect of tides in long‐perforated boreholes. Electric conductivity (EC) fluctuations in the coastal aquifer of Israel, as measured in long‐perforated borehole, were found to have the same periodicities as the sea tide, though some orders of magnitude larger than sea‐level or groundwater level fluctuations. Direct measurements in the aquifer through buried EC sensors demonstrate that EC measurements within the long‐perforated boreholes might be distorted due to vertical flow in the boreholes, whereas actual fluctuations of the transition zone within the aquifer are some orders of magnitude smaller. Considering these field data, we suggest that monitoring of the transition zone between fresh and saline water adjacent to the sea through long‐perforated boreholes is unreliable. EC fluctuations in short‐perforated boreholes (1 m perforation at the upper part of the transition zone) were somewhat larger than in the aquifer, but much smaller than those in the long‐perforated borehole. The short‐perforation diminishes the vertical flow and the distortion and therefore is more reliable for monitoring the transition zone in the shoreline vicinity. 相似文献
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Oussama Abidi Mohamed Hédi Inoubli Kawthar Sebei Adnen Amiri Haifa Boussiga Imen Hamdi Nasr Abdelhamid Ben Salem Mahmoud Elabed 《Surveys in Geophysics》2017,38(3):617-649
The Maastrichtian–Paleocene El Haria formation was studied and defined in Tunisia on the basis of outcrops and borehole data; few studies were interested in its three-dimensional extent. In this paper, the El Haria formation is reviewed in the context of a tectono-stratigraphic interval using an integrated seismic stratigraphic analysis based on borehole lithology logs, electrical well logging, well shots, vertical seismic profiles and post-stack surface data. Seismic analysis benefits from appropriate calibration with borehole data, conventional interpretation, velocity mapping, seismic attributes and post-stack model-based inversion. The applied methodology proved to be powerful for charactering the marly Maastrichtian–Paleocene interval of the El Haria formation. Migrated seismic sections together with borehole measurements are used to detail the three-dimensional changes in thickness, facies and depositional environment in the Cap Bon and Gulf of Hammamet regions during the Maastrichtian–Paleocene time. Furthermore, dating based on their microfossil content divulges local and multiple internal hiatuses within the El Haria formation which are related to the geodynamic evolution of the depositional floor since the Campanian stage. Interpreted seismic sections display concordance, unconformities, pinchouts, sedimentary gaps, incised valleys and syn-sedimentary normal faulting. Based on the seismic reflection geometry and terminations, seven sequences are delineated. These sequences are related to base-level changes as the combination of depositional floor paleo-topography, tectonic forces, subsidence and the developed accommodation space. These factors controlled the occurrence of the various parts of the Maastrichtian–Paleocene interval. Detailed examinations of these deposits together with the analysis of the structural deformation at different time periods allowed us to obtain a better understanding of the sediment architecture in depth and the delineation of the geodynamic evolution of the region. 相似文献
16.
文中采用钻探技术对南口-孙河断裂带进行了试验探测研究,并通过层序地层学、岩性岩相分析、磁化率分析与年代测定等方法建立了钻孔联合剖面,进而研究了断层距今60ka以来的多期活动特征,得出断裂带的3个活跃期是60～47kaBP、36～28kaBP与16kaBP以来,其余时段为相对平静期。断裂带的平均垂直位错速率,距今60～37ka之间约为0.35mm/a,37～32ka之间为0mm/a,32～12ka之间为0.78mm/a,12ka以来为0.35mm/a。研究认为,与传统的岩性、沉积相分析方法相比,层序地层学方法在钻孔地层对比与隐伏断层活动分期研究中有一定的优势 相似文献
17.
ALUN L. HUBBARD 《地球表面变化过程与地形》1997,22(1):79-92
A one-dimensional flowline model has been constructed, tested and applied to two formerly glaciated valley basins within the Chilean Lake District. The vertically integrated ice flow model is similar to those used to study historical fluctuations of European Alpine glaciers and includes terms for internal deformation and basal sliding. In addition, longitudinal deviatoric stresses are computed and velocity terms are correspondingly adjusted. The model is driven through a mass balance term forced by a stepped lowering of the equilibrium line altitude (ELA) through time. Experiments, based on generating equilibrium glacier surface profiles corresponding to various ELAs, indicate that a lowering of at least 1000 m of the ELA from its present-day position is required to simulate the glacial maximum. Furthermore, the specific geometry of the two valleys provides an important control on the extent of the two glaciers, effectively decoupling them from further climatic deterioration once they have advanced beyond the constraining influence of their valleys into the piedmont zone. The tight nesting of terminal moraine loops provides evidence for this topographical control on palaeoglacier extent. The modelled response and sensitivity of the two palaeoglaciers to climate change differ markedly as a result of contrasting valley geometry. Glaciers resting on steeper gradients tend to have thinner profiles, faster mass turnover times and correspondingly shorter volume time-scales. Puyehue glacier has a response time of c. 1000 years whereas the Rupanco glacier has a response time of c. 2000 years. Hence, Puyehue is more sensitive to climatic fluctuations occurring on a time-scale of 500–1000 years. Furthermore, the Rupanco glacier may lag or even fail to respond at all to climatic fluctuations at these time-scales, a conclusion substantiated by field evidence. © 1997 by John Wiley & Sons, Ltd. 相似文献
18.
《Earth and Planetary Science Letters》2006,241(3-4):663-671
Understanding spin orbital parameter-driven climate change on Mars prior to ∼ 20 Ma ago requires geological evidence because numerical solutions for that period are chaotic and non-unique. We show geological evidence that lineated valley fill at low mid-latitudes in the northern hemisphere of Mars (∼ 37.5° N) originated through regional snow and ice accumulation and underwent glacial-like flow. Breached upland craters and theater-headed valleys reveal features typical of erosion in association with terrestrial glaciers. Parallel, converging and chevron-like lineations in potentially ice-rich deposits on valley floors indicate that flow occurred through constrictions and converged from different directions at different velocities. Together, these Martian deposits and erosional landforms resemble those of intermontaine glacial systems on Earth, particularly in their major morphology, topographic shape, planform and detailed surface features. An inferred Late Amazonian age, combined with predictions of climate models, suggest that the obliquity of Mars exceeded a mean of 45° for a sustained period. During this time, significant transfer of ice occurred from ice-rich regions (e.g., the poles) to mid-latitudes, causing prolonged snow and ice accumulation there and forming an extensive system of valley glaciers. 相似文献
19.
A well‐preserved Eemian incised‐valley fill in the southern North Sea Basin,Belgian Continental Shelf ‐ Coastal Plain: Implications for northwest European landscape evolution 
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下载免费PDF全文 M. De Clercq T. Missiaen J. Wallinga O. Zurita Hurtado A. Versendaal M. Mathys M. De Batist 《地球表面变化过程与地形》2018,43(9):1913-1942
This paper demonstrates that the Belgian Continental Shelf and coastal plain occupy a key position between the depositional North Sea Basin and the erosional area of the Dover Strait as it is an area where erosional landforms and fragmented sedimentary sequences provide new evidence on northwest European landscape evolution. The study area hosts 20–30 m thick penultimate to last glacial sand‐dominated sequences that are preserved within the buried palaeo‐Scheldt Valley. Here, we build on the results of previous seismo‐ and lithostratigraphical studies, and present new evidence from biostratigraphical analysis, OSL dating and depth‐converted structure maps, together revealing a complex history of deposition and landscape evolution controlled by climate change, sea‐level fluctuations and glacio‐isostasy. This study presents strong new supportive evidence on the development of the incised palaeo‐Scheldt Valley landform that became established towards the end of the penultimate glacial period (MIS 6; Saalian) as a result of glacio‐isostatic forebulge updoming, proglacial lake drainage and subsequent collapse of a forebulge between East Anglia and Belgium following ice‐sheet growth, disintegration and retreat in areas to the north. The majority of the incised‐valley fill is of estuarine to shallow marine depositional context deposited during the transgression and high‐stand of the last interglacial (MIS 5e: Eemian). A thin upper part of the valley fill consists of last glacial (MIS 5d‐2: Weichselian) fluvial sediments that show a gradual decrease and retreat of fluvial activity to inland, upstream reaches of the valley system until finally the valley ceases to exist as the combined result of climate‐driven aeolian activity and possibly also glacio‐isostatic adjustment. Thus, strong contrasts exist between the palaeo‐Scheldt Valley and estuary systems of the penultimate glacial maximum to Last Interglacial (Saalian, Eemian), the beginning of the Last Glacial (Weichselian Early Glacial and Early‐Middle Pleniglacial), and the Last Glacial Maximum to Holocene. Copyright © 2018 John Wiley & Sons, Ltd. 相似文献
20.
M. M. ROKSANDI&#x; 《Geophysical Prospecting》1978,26(2):383-398
Seismic facies analysis makes use of different seismic parameters in order to get other than structural information. A review is given of possibilities and usefulness of seismic facies analysis in oil exploration. A seismic facies unit can be defined as a sedimentary unit which is different from adjacent units in its seismic characteristics. Parameters that should be taken into consideration in the seismic facies analysis are as follows: reflection amplitude, dominant reflection frequency, reflection polarity, interval velocity, reflection continuity, reflection configuration, abundance of reflections, geometry of seismic facies unit, and relationship with other units. Interpretation of seismic facies data may be either direct or indirect. The purpose of the direct interpretation is to find out geological causes responsible for the seismic signature of a seismic facies unit. So, the direct interpretation may be aimed at predicting lithology, fluid content, porosity, relative age, overpressured shales, type of stratification, geometry of the geological body corresponding to the seismic facies unit and its geological setting. The indirect interpretation is intended to reach some conclusions on depositional processes and environments, sediment transport direction, and some aspects of geological evolution (transgression, regression, subsidence, uplift, erosion). The results of the seismic facies analysis may be shown on seismic facies cross-sections and seismic facies maps. Depending on the available seismic data and geological conditions in the area under consideration, the seismic facies maps may be of different types such as general seismic facies maps showing distribution of different seismic facies units, sand-shale ratio maps, direction of cross-bedding and paleo-transport maps etc. Several kinds of seismic facies units and their geological interpretation are discussed as examples of seismic facies analysis. 相似文献