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1.
V. B. Kaplun 《Russian Journal of Pacific Geology》2013,7(3):151-166
The results of magnetotelluric sounding are analyzed along the Korfovo-Astashikha-Novosergeevka profile 200 km long in the south of the Amur-Zeya sedimentary basin. The Korfovo-Astashikha and Korfovo-Novosergeevka profiles were sounded in the AMT and AMT + MTS regimes with a step between the observation points of 1 and 5 km, respectively. The shape of the MTS curves, their variations along the profiles, the shape of the polar plots of the main and additional impedance, and the parameters of the heterogeneity (N) and asymmetry (skew) are characterized. The dimensions of the geological medium is estimated and methods of the interpretation of the magnetotelluric data are chosen. The geoelectric sections are constructed for the depths of 3 and 150 km. The structure and electric properties of the sedimentary cover, the Earth’s crust, and the upper mantle are characterized. The thickness of the sedimentary cover in the grabens of the basin attains 1.5–1.7 km. Blocks with various resistivities were identified in the basement. Based on the contrasting changing of the electric resistances, the thickness of the Earth’s crust was determined as 38–40 km, which agrees with that established by the seismic data. The geoelectric structure of the upper mantle of the basin is relatively simple. A layer of elevated resistivity from the first hundreds up to a thousand Ohm · m was identified in the background of the low electric resistivity (20–30 Ohm · m) of the mantle in the depth range of 50–80 km. This layer is discrete and divided on the blocks by the zones of the decreased resistivity penetrating to the middle part of the Earth’s crust and coinciding with faults of various origins. The petroleum prospectives are estimated for the individual grabens of the basin. 相似文献
2.
Heat flow increases northward along Intermontane Belt in the western Canadian Cordillera, as shown by geothermal differences
between Bowser and Nechako sedimentary basins, where geothermal gradients and heat flows are ∼30 mK/m and ∼90 mW/m2 compared to ∼32 mK/m and 70 –80 mW/m2, respectively. Sparse temperature profile data from these two sedimenatary basins are consistent with an isostatic model
of elevation and crustal parameters, which indicate that Bowser basin heat flow should be ∼20 mW/m2 greater than Nechako basin heat flow. Paleothermometric indicators record a significant northward increasing Eocene or older
erosional denudation, up to ∼7 km. None of the heat generation, tectonic reorganization at the plate margin, or erosional
denudation produce thermal effects of the type or magnitude that explain the north–south heat flow differences between Nechako
and Bowser basins. The more southerly Nechako basin, where heat flow is lower, has lower mean elevation, is less deeply eroded,
and lies opposite the active plate margin. In contrast, Bowser basin, where heat flow is higher, has higher mean elevation,
is more deeply eroded, and sits opposite a transform margin that succeeded the active margin ∼40 Ma. Differences between Bowser
and Nechako basins contrast with the tectonic history and erosion impacts on thermal state. Tectonic history and eroded sedimentary
thickness suggest that Bowser basin lithosphere is cooling and contracting relative to Nechako basin lithosphere. This effect
has reduced Bowser basin heat flow by ∼10–20 mW/m2 since ∼40 Ma. Neither can heat generation differences explain the northerly increasing Intermontane Belt heat flow. A lack
of extensional structures in the Bowser basin precludes basin and range-like extension. Therefore, another, yet an unspecified
mechanism perhaps associated with the Northern Cordilleran Volcanic Province, contributes additional heat. Bowser basin’s
paleogeothermal gradients were higher, ∼36 mK/m, before the Eocene and this might affect petroleum and metallogenic systems. 相似文献
3.
The Direct Current resistivity method was applied to the consolidated coastal Plioquaternary aquifer of Mamora plain, located on the Atlantic coast of Morocco. The aim is to determine the depth of the base of the saturated zone in the aquifer and to help in imaging lateral and vertical distribution of groundwater salinity. The geoelectric survey showed four geoelectric formations with the following electrical resistivities from top to bottom: 20–80, 200–2000, 200–300 and 5–70 Ohm m. The latter designates the basement of the aquifer constituted of marls and sandy marls. The mean resistivity of 250 Ohm m designates the aquifer formation. It decreases to less than 25% of its initial values for the soundings near the shore, reflecting the oceanic impact on the aquifer formation resistivity. The contour map shows that the basement of the saturated zone in the aquifer is deeper in the Northwest near the Sebou River estuary with values up to 70 m below sea level. This results in a larger thickness of the saturated zone of the aquifer leading to a consequent hydraulic potential. On the other hand, it has been deduced that the extent of marine intrusion inside the continent can be governed by human activities, natural properties and substratum geometry of the aquifer as well as by ecological factors. An optimal network of electrical soundings has been proposed for the monitoring of saltwater intrusion. 相似文献
4.
EH-4的应用效果受采集频段、地质及地球物理条件的影响。为了判断在地质物探工作中选择EH-4是否合理,分析了EH-4在连山关硬岩型铀矿勘查、二连盆地砂岩型铀矿勘查及新疆伊利盆地采空区工程勘查中的应用效果,认为在硬岩地区,EH-4的勘查深度普遍能达到1 000 m左右,且其对探测断裂和岩体接触带的走向和空间展布有较好的应用效果;在沉积盆地地区,EH-4受整体电阻率和地表电阻率的影响,其勘查深度少则二三百米,多则五六百米,变化较大,虽然勘查深度不大,但其对浅部地电性质的反映效果较好。 相似文献
5.
A. P. Sorokin Yu. F. Malyshev V. B. Kaplun A. T. Sorokina T. V. Artemenko 《Russian Journal of Pacific Geology》2013,7(2):77-91
The evolution and deep structure of the Songliao and Zeya-Bureya basins can be divided into the rift, platform (subsidence), and neotectonic phases. The rift phase (Middle Jurassic-Early Cretaceous) climaxed at the formation of a basin-wide near N-S-oriented rift system, which was followed (Late Cretaceous) by the deposition of the deep-water organic-rich lacustrine source facies with the maximum thickness identified in the Songliao basin (up to 1100 m). The neotectonic phase was marked by the pronounced differences in the basin’s development caused by the formation of a series of E-W-trending transverse structures, which eventually separated the basins, changed the drainage pattern, and blocked the rivers draining southwards from the Zeya-Bureya to the Songliao basin. The differences in the deep structure of the basins are also strongly pronounced. High heat flow values of more than 70 mW/m2 are typical of the Songliao basin, and its mantle heat flow component is higher than the crustal one, as compared to the Zeya-Bureya basin (below 50 mW/m2). The crustal thickness of the Zeya-Bureya basin is higher than that of the Songliao basin (38–42 km and 29–34 km) with a lithospheric thickness of 110–140 km and 50–75 km, respectively. The only exception is the southern Zeya-Bureya basin, which has an electrical structure similar to that of the Songliao basin. These differences have important implications for the evaluation of the hydrocarbon potential of the rift basins. It was suggested that the evaluation of the hydrocarbon potential of the sedimentary basins or parts of these basins should account for two factors: (1) the influence of the lithospheric motions and the related collisional processes and (2) the anomalies in the deep lithospheric structures (the high heat flow and the reduced crustal and lithospheric thickness). The results of this study indicate that the southern part of the Zeya-Bureya basin (in particular, the Lermontovka, Dmitrievka, Mikhailovka, Ekaterinoslavka, and Arkhara troughs) is interpreted to have a fairly high hydrocarbon potential. 相似文献
6.
Abdalla E. M. Elsheikh Khalid A. Elsayed Zeinelabdein Sami O. H. El Khidir Abdalla E. Ibrahim 《Arabian Journal of Geosciences》2014,7(2):789-797
Abu Deleig area is a transitional area between the Butana basement terrain to the east; and the Khartoum and Shendi sedimentary basins to the west and northwest directions, respectively. The existence of sedimentary basins within this region of Sudan was previously unknown. Landsat images have been used for delineation of lineaments and drainage system, followed by a structural analysis and geophysical investigations including gravity and resistivity methods. The interpretation of the remotely sensed data revealed that the drainage pattern is structurally controlled. The structural analysis defined the trends of the shear and tensional fractures. The structural analysis revealed that Wadi Al Hawad is the southern continuation of the Keraf Shear Zone. The related minor fractures in a NE–SW direction exhibit normal faults governing the geometry of the Abu Deleig sub-basin. The geophysical investigations confirmed the findings of structural analysis and portrayed the subsurface geometry of the sub-basin. The newly discovered sub-basin has a prism-like shape with its apex occurring at Abu Deleig town and extends to 40 km in NW direction. The depth to the basement increases from 20 m at Abu Deleig in step form to more than 300 m, where it is linked with the Shendi Basin in the northwestern part. The results of this study, however, did not confirm any link of Abu Deleig sub-basin with Atbara Basin to the NE or Khartoum Basin to the west as have been previously suggested. 相似文献
7.
Geological and seismic profiling data (more than 25000 km of seismic profiles and about 1000 sediment sampling stations) collected
during the last 30 yr by research vessels of the Shirshov Institute of Oceanology, Russian Academy of Sciences are summarized.
Seismic records are directly correlated with sediment cores. The distribution map (scale 1 : 500000) of Quaternary lithofacial
complexes corresponding to certain stages of the Baltic Sea evolution is compiled. The following four complexes are distinguished
(from the base to the top): (I) moraine, with maximum thicknesses 60 and 170 m in valleys and ridges respectively: (II) varved
clay of periglacial basins and from the Baltic Ice Lake (BIL), up to 25 m thick in depressions; (III) lacustrinemarine homogeneous
clay with a thickness up to 4–8 m in depressions; (IV) marine sediments (mud, aleurite, coarse-grained deposits) accumulated
in environments with intense bottom currents activity (thickness 2–4 m in the Gotland Basin, 4–6 m in the Gdansk Basin, and
10–20 m in fans and prodeltas). The Quaternary sequence is cut through by inherited valleys, where the thickest Holocene sediments
are noted. Today, these valleys serve as routes of sediment transport to slope bases and central parts of basins. Outblows
of deep gas (through faults and fractures) and diagenetic gas (from sediments) to the bottom surface also occur in the valleys.
Sedimentation rates are higher in the Gdansk Basin (up to 100–120 cm/ka). Thick sand, aleurite, and mud bodies are accumulated
here (about 15–20 m in the Visla River prodelta). The sedimentation rate is slower in the Gotland Basin (up to 50–60 cm/ka),
where thin (2–4 m) sections of more fine-grained mud occur 相似文献
8.
Magnetotelluric soundings (MTS) were conducted in a broad frequency range of 10 kHz to 0.001 Hz at a total of fifty-seven sounding sites of the profile spaced 5 km apart and intersecting the northern Sikhote-Alin across the strike. The analysis of the obtained magnetotelluric parameters has been made which shows three-dimensional geoelectric nonuniformities in the lower crust and upper mantle. The MTS curve interpretation was carried out in the framework of a three-dimensional model. As a result of the inverse problem solution, the geoelectric section has been constructed down to 150 km depth. The section distinguishes the crust with a resistivity higher than 1000 Ohm m and variable thickness between 30 and 40 km which is consistent with deep seismic sounding (DSS) data. The crust is subdivided into four blocks by deep faults, and each block is characterized by a set of parameters. The data support the existence of the Vostochny deep fault in the study area, whereas, on the contrary, the deep roots for the Central Sikhote-Alin fault have not been established. The upper mantle structure is nonuniform; three low-resistivity zones are identified that coincide with the boundaries of crustal blocks. In the revealed zones, an increase in the resistivity is noted from the continent to the Tatar Strait coast. A high-resistivity layer of 300–400 Ohm m was observed in the coastal area, which was steeply dipping from the crustal base down to 120 km depth and extended beneath the continent. Based on a set of geological and geophysical data, the ancient subducting plate is suggested in this area, and the evolutionary model of the region is proposed starting from the Late Cretaceous. The most probable mechanism of conductivity within the upper mantle is determined from petrological and petrophysical data. The low resistivity values are linked to dry peridotite mantle melting. 相似文献
9.
Wakgari Furi Moumtaz Razack Tigistu Haile Tamiru A. Abiye Dagnachew Legesse 《Environmental Earth Sciences》2011,62(6):1323-1335
Rise of groundwater level becomes an emerging concern at Wonji irrigation field, Main Ethiopian Rift. An integrated study
based on geophysical resistivity methods is conducted at Wonji wetland to understand the link between irrigation water and
the shallow aquifer system as well as to confirm the current concern of groundwater rise. The study was also intended to improve
the uncertainty of understanding the hydrogeology of Wonji wetland including the extent and direction of groundwater–surface
water interaction. The vertical and horizontal contacts between the different geological series of the Wonji area are resolved
with 2D high-resolution geophysical imaging. Results from both VES and 2D tomography show low resistivity layers under Wonji
irrigation field with narrow ranges in resistivity variation which corresponds to a homogeneous saturated layer. The geoelectric
sections reveal two fault systems running NW–SE and N–S directions which impede lateral groundwater flow. Furthermore, groundwater
is converged towards the Wonji irrigation site strained by these fault systems. The geophysical results show strong link between
irrigation water and the shallow unconfined aquifer as well as among the local and regional flow systems. 相似文献
10.
Umar Hamzah Rahman Yaacup Abdul Rahim Samsudin Mohd Shahid Ayub 《Environmental Geology》2006,49(8):1156-1162
A geophysical study was carried out in the Banting area of Malaysia to delineate groundwater aquifer and marine clay layer
of the alluvial Quaternary deposits of Beruas and Gula Formations. The Beruas Formation is formed by peat and clayey materials
as well as silt and sands, whereas the Gula Formation consists of clay, silt, sand and gravels. Both Formations were deposited
on top of the Carboniferous shale of the Kenny Hill Formation. A 2-D geoelectrical resistivity technique was used. Resistivity
measurement was carried out using an ABEM SAS 4000 Terrameter. The 2-D resistivity data of subsurface material for each survey
line was calculated through inverse modelling and then compared with borehole data. The resistivity images of all the subsurface
material below the survey lines show similar pattern of continuous structure of layering or layers with some lenses with resistivity
ranging from 0.1 to 50 Ωm. The upper layer shows resistivity values ranging from 0.1 to 10 Ωm, representing a clay horizon
with a thickness up to 45 m. The second layer with depth varies from 45 to 70 m below surface and has resistivity values ranging
from 10 to 30 Ωm. Borehole data indicate coarse sand with some gravels for this layer, which is also the groundwater aquifer
in the study area. The lowermost layer at a depth of 70 m below ground level shows resistivity values ranging from 30–50 Ωm
and can be correlated with metasedimentary rocks consisting of shale and metaquartzite. 相似文献
11.
The existence of gas-hydrates in marine sediments increases the seismic velocity, whereas even a small amount of underlying
free-gas reduces the velocity considerably. The change in velocities against the background (without gas-hydrates and free-gas)
velocity can be used for identification and assessment of gas-hydrates. Traveltime inversion of identifiable reflections from
large offset multi channel seismic (MCS) experiment is an effective method to derive the 2-D velocity structure in an area.
We apply this method along a seismic line in the Kerala-Konkan (KK) offshore basin for delineating the gas-hydrates and free-gas
bearing sediments across a bottom simulating reflector (BSR). The result reveals a four layer 2-D shallow velocity model with
the topmost sedimentary layer having velocity of 1,680–1,740 m/s and thickness of 140–190 m. The velocity of the second layer
of uniform thickness (110 m) varies from 1,890 to 1,950 m/s. The third layer, exhibiting higher velocity of 2,100–2,180 m/s,
is interpreted as the gas-hydrates bearing sediment, the thickness of which is estimated as 100 to 150 m. The underlying sedimentary
layer shows a reduction in seismic velocity between 1,620 to 1,720 m/s. This low-velocity layer with 160–200 m thickness may
be due to the presence of free-gas below the gas-hydrates layer. 相似文献
12.
A geophysical survey was conducted to determine the depth of the base of the water-table aquifer in the southern part of
Jackson Hole, Wyoming, USA. Audio-magnetotellurics (AMT) measurements at 77 sites in the study area yielded electrical-resistivity
logs of the subsurface, and these were used to infer lithologic changes with depth. A 100–600 ohm-m geoelectric layer, designated
the Jackson aquifer, was used to represent surficial saturated, unconsolidated deposits of Quaternary age. The median depth
of the base of the Jackson aquifer is estimated to be 200 ft (61 m), based on 62 sites that had sufficient resistivity data.
AMT-measured values were kriged to predict the depth to the base of the aquifer throughout the southern part of Jackson Hole.
Contour maps of the kriging predictions indicate that the depth of the base of the Jackson aquifer is shallow in the central
part of the study area near the East and West Gros Ventre Buttes, deeper in the west near the Teton fault system, and shallow
at the southern edge of Jackson Hole. Predicted, contoured depths range from 100 ft (30 m) in the south, near the confluences
of Spring Creek and Flat Creek with the Snake River, to 700 ft (210 m) in the west, near the town of Wilson, Wyoming.
Received, May 1997 · Revised, February 1998 · Accepted, April 1998 相似文献
13.
14.
15.
M. D. Khutorskoi L. V. Podgornykh O. I. Suprunenko B. I. Kim A. A. Chernykh 《Doklady Earth Sciences》2011,440(2):1381-1386
2D and 3D geotemperature models of the sedimentary cover within the Laptev Sea shelf have been calculated. The presence of
several “thermal domes” (zones of uplifted isotherms) has been found. Based on analogous sedimentary basins with domes, which
correlate to the location of hydrocarbon deposits, the forecasting has been made that the Ust-Lena graben and Omoloi trough
are the most promising areas for oil-and-gas prospecting. 相似文献
16.
Tectonics,stress state,and geodynamics of the Mesozoic and Cenozoic Rift basins in the Baikal region
The results of geological, structural, tectonic, and geoelectric studies of the dry basins in the Baikal Rift Zone and western
Transbaikalia, combined under the term Baikal region, are integrated. Deformations of the Cenozoic sediments related to pulsing
and creeping tectonic processes are classified. The efficiency of mapping of the fault-block structure of the territories
overlapped by loose and poorly cemented sediments is shown. The faults mapped at the ground surface within the basins are
correlated with the deep structure of the sedimentary fill and the surface of the crystalline basement, where they are expressed
in warping and zones of low electric resistance. It is established that the kinematics of the faults actively developing in
the Late Cenozoic testifies to the relatively stable regional stress field during the Late Pliocene and Quaternary over the
entire Baikal region, where the NW-SE-trending extension was predominant. At the local level, the stress field of the uppermost
Earth’s crust is mosaic and controlled by variable orientation of the principal stress axes with the prevalence of extension.
The integrated tectonophysical model of the Mesozoic and Cenozoic rift basin is primarily characterized by the occurrence
of mountain thresholds, asymmetric morphostructure, and block-fault structure of the sedimentary beds and upper part of the
crystalline basement. The geological evolution of the Baikal region from the Jurassic to Recent is determined by alternation
of long (20–115 Ma) epochs of extension and relatively short (5.3–3.0 Ma) stages of compression. The basins of the Baikal
Rift System and western Transbaikalia are derivatives of the same geodynamic processes. 相似文献
17.
Surface geophysical investigations of landslide at the Wiri area in southeastern Korea 总被引:1,自引:1,他引:0
A geophysical survey was undertaken at Wiri area of the Andong in southeastern Korea to delineate subsurface structure and
to detect the fault zone, which affected the 1997 mountain–hill subsidence and subsequent road heaving initiated by the intense
rainfall. Electrical resistivity methods of dipole–dipole array profiling and Schlumberger array sounding and seismic methods
of refraction and reflection profiling were used to map a clay zone, which was regarded as the major factor for the landslide.
The clay zone was identified in electrical resistivity and seismic sections as having low electrical resistivity (<100 Ωm)
and low seismic velocity (<400 m/s), respectively. The clay zone detected by using geophysical methods is well correlated
with its distribution from the trench and drill-core data. The results of the electrical and seismic surveys showed that slope
subsidence was associated with the sliding of saturated clay along a fault plane trending NNW–SSE and dipping 10°–20° SW.
However, the road heaving was caused by the slope movement of the saturated clay along a sub-vertical NNE-trending fault. 相似文献
18.
镜质体反射率在重建盆地古地温中的应用──中国东部、西部中、新生代沉积盆地古地温特征 总被引:5,自引:0,他引:5
在总结前人关于镜质体反射率重建盆地古地温方法的基础上,讨论了各方法的理论基础、应用效果及其局限性。选择理论上与实际应用效果较好的EasyR0方法,重建了东部苏北盆地、辽河盆地和西部柴达木盆地、三塘湖盆地典型探井的古地温演化模式。结果表明我国东部中、新代大陆架谷型盆地,具有比酉部中、新生代前陆型盆地更高的古地温梯度。中生代末至第三纪早期,东部盆地的古地温梯度大于4.0℃/100m,而西部盆地的在3.0~2.5℃/100m。我国中、新生代沉积盆地古地温普遍具有从高到低的演化趋势,而柴达木盆地则相反,古地温梯度自早第三纪的2.5℃/100m升高到现今的3.0℃/100m。这几个盆地古地温的成功恢复,证实EasyR0方法对热演化各异的不同类型盆地古地温恢复具有广泛的适应性,而且,准确性高。过去常用的TTI-R0方法过高地计算了有机质的成熟度,使重建的古地温偏低。 相似文献
19.
Authors collected 38 sedimentary boreholes and numerous seismic profiles from previous publications to delineate the Holocene
sedimentation rate of six major depositional sinks in the middle-lower Changjiang River basins and its river coast. The results
demonstrate that the highest sedimentation rate of ca. 15 m/ka occurred in the mono-depositional sink of the former Changjiang
River mouth during 10 000–8000 aBP, when post-glacial transgression happened and the Changjiang water level remained at lower
stand. With the rising of the Changjiang water level in response to sea level rise, Jianghan Basin of the middle Changjiang
River becomes the other important depositional sink with highest sedimentation rate of 10 m/ka since 7000 aBP. As Jianghan
Basin was mostly filled up at ca. 4000 aBP, Dongting Basin and the lower Changjiang valley trapped sediments in great amounts
like in the river mouth. A considerable amount of Changjiang sediments has been delivered, both eastward and southward, to
the inner continental shelf of the East China Sea, especially after 2000 aBP. This indicates reduced sediment storage capacity
of the middle-lower Changjiang valley and the river mouth. In total, ca. 1307.4 billion tons of sediment have deposited in
the middle-lower Changjiang floodplain since 7000 aBP. In the meantime, ca. 947 billion tons of sediment have been deposited
in the river coast to form the Changjiang subaqueous delta and the Zhejiang-Fujian along-shelf mud wedge. Our result also
reveals two time stages with lower sedimentation rates(< 4 m/ka) in all basins during 8000–7000 aBP and in the estuarine area
during 4000–2000 aBP, probably owing to stengthened chemical weathering of decline of monsoon precipitation.
__________
Translated from Journal of Palaeogeography, 2007, 9(4):419–429 [译自: 古地理学报] 相似文献
20.
Sediment mass volumes for periods since the Oligocene (E3, N1
1, N1
2, N1
3, N2, and Q) in the South China Sea (SCS) were calculated on the basis of geological and geophysical data including ODP borehole
data. Above the pre-Oligocene base, the estimated sediment volume is 7.01 × 106 km3 and the mass is 1.44 × 1016 t for the entire SCS, with an average sedimentation rate of 6.22 cm/ka and accumulation rate of 12.8 g/(cm2·ka) since the Oligocene. Most of the sediment was deposited on the continent shelf and slope, while only 5% of the total
mass accumulated in the Central Basin. Sediment basins on shelf and slope occupy 34% of the entire SCS area bounded by the
2 000 m thickness contour, but receive more than 82% of the total sediment mass, indicating that sediment basins played a
central role of sedimentary process in the SCS. The highest sedimentation rate and the largest mass volume occurred in the
Oligocene SCS, which is quite different from global sedimentation rate patterns. Therefore, we conclude that deposition in
marginal seas was primarily controlled by local tectonics.
Translated from Advances in Earth Science, 2006, 21(5): 465–473 [译自: 地球科学进展] 相似文献