石油实验地质

2008, 30(4)

Abstract(282) PDF-CN(266)

Abstract:

CHARACTERISTICS OF THE CARBONIFEROUS-PERMIAN VOLCANIC ROCKS AND HYDROCARBON ACCUMULATIONS IN TWO GREAT BASINS, XINJIANG AREA

Kang Yuzhu

2008, 30(4): 321-327. doi: 10.11781/sysydz200804321

Abstract(940) PDF-CN(447)

Abstract:
The Carboniferous-Permian volcanic rocks were very well developed with wide distribution and big thickness in the Junggar and Tarim basins,Xinjiang area.The Carboniferous volcanic rocks are widely distributed in the West Uplift,Luliang Uplift,Central Uplift and East Uplift of the Junggar Basin,which can be divided into upper and lower Carboniferous(total 5 formations).The quantity of the Permian volcanic rocks is small.The tuffs and tuffaceous sandstones are shown in only certain layers.The Carboniferous volcanic rocks of the Tarim Basin are mainly distributed at the margin of basin but the Permian volcanic rocks are common in the whole basin with large thickness and variety of rock types.The main types are basic and ultrabasic rocks and then are intermediate-acid rocks.Their distribution is characterized by lateral zonation and vertical cyclicity.The volcanism accelerated immature source rocks to enter oil generation threshold in advance,at the same time it also caused mature source rocks became over matured.Intermediate-acid volcanic lava is the main reservoirs of the Carboniferous.Magmatism activities provide the pathway for hydrocarbon migration.The volcanic rocks can form big oilfields of 100 million tons so we should focus on study of reservoir-forming and distributions of the Carboniferous-Permian volcanic rocks in oil-gas exploration of Xinjiang area and regard these reservoirs as one of important targets in petroleum exploration.

RELATIONSHIP BETWEEN VOLCANIC FACIES AND GAS ACCUMULATION IN THE CHANGLING FAULT-DEPRESSION OF THE SONGLIAO BASIN

Qin Weijun, Liu Chaoying, Tan Fengqi, Gao Zhongzhe, Mao Genta

2008, 30(4): 328-332. doi: 10.11781/sysydz200804328

Abstract(723) PDF-CN(309)

Abstract:
Caprock structure in the Songliao Basin is composed of the upper depression layers and the lower fault-depression layers.The Changling Fault-Depression(part of the fault-depression layers) is a deep-large fault-depression controlled by the Sunwu-Shuangliao and the Songhuajang-Siping Deep Fault Belts generated during basin early phase.Deep faults in and around the fault-depression cut deep into lithosphere,causing volcanic activities,resulting in association of volcanic rocks and lacustrine facies sedimentary rocks.Volcanic rocks are mainly acid,and can be divided into 2 types: explosive and outpouring.The 2 facies alternate and compose multiple volcanic activity cycles.Primary vesicles gene-rate in the upper subfacies of the explosive facies.Pores and caverns generate in the aerial-falling and thermodynamic wave subfacies of the outpouring facies.Good reservoirs generate controlled by the upper subfacies of the explosive facies and the aerial-falling and thermodynamic wave subfacies of the outpouring facies;hence control gas accumulation formation.

DISTRIBUTION REGULARITY OF HIGH-QUALITY RESERVOIRS IN THE EASTERN SULIGE GAS FIELD, THE ORDOS BASIN

Yang Binhu, Liu Xiaohong, Luo Jinglan, Wei Xinshan, Yao Jingli, Liu Xinshe, Hou Yundong, Wang Huaichang

2008, 30(4): 333-339. doi: 10.11781/sysydz200804333

Abstract(744) PDF-CN(303)

Abstract:
It is of practical significance in accelerating the progress of natural gas exploration and deve-lopment to analyze controlling factors and spatial distribution patterns of high-quality reservoirs.Major controlling parameters of diagenesis and diagenetic facies on spatial distribution patterns of high-quality reservoirs of Upper Paleozoic in the eastern Sulige Gas Field of the Ordos Basin are discussed in this paper,based upon detailed description and observation of drilling cores,accompanied with various analytical and measurements including identification and quantitative statistics of thin sections under microscope,grain size analysis,electron scan microscope(ESM),capillary pressure analysis and measurement of homogeneous temperature for inclusions.Research shows that detrital grain size,sandstone types and diagenetic differences of sandstones are the main controlling factors for reservoir quality.Nine diagenetic facies can be recognized.The quartz overgrowth cementation mixture pores diagenetic facies,authigenic kaolinite cementation inter-crystal pores diagenetic facies,and clay matrix filling dissolution facies distributed between dense diagenetic facies are the most profitable diagenetic zones for high-quality reservoirs.Micro-fractures and dissolution are the key parameters for high-quality reservoirs formation.

STUDY OF THE ABNORMAL HIGH-PRESSURE IN HYDROCARBON SOURCE ROCKS-TAKING PALEOGENE IN THE DONGYING SAG, THE BOHAI BAY BASIN AS AN EXAMPLE

Zhao Guoxin

2008, 30(4): 340-344. doi: 10.11781/sysydz200804340

Abstract(687) PDF-CN(304)

Abstract:
The abnormal high-pressure is very important to oil and gas accumulation.There is abnormal high-pressure in the 3rd and 4th member of Shahejie Formation of Paleogene all over the Dongying Sag,the Bohai Bay Basin.The main factors that lead to the pressure are under-compaction and hydrocarbon generation in the source rocks.The overpressure area is well corresponding with the thickness of source rocks.The present abnormal high-pressure is mainly distributed at a depth range 2 700 m to 3 500 m,and the range becomes bigger with increasing of the buried depth.Times of abnormal high-pressure should be considered when applying abnormal high-pressure to hydrocarbon accumulation.The present abnormal high-pressure in the source rocks has an active effect on the saving of oil and gas and it is oil source kitchen in future.The ancient abnormal high-pressure took an active part in the hydrocarbon migration in the source rocks and there is the main accumulation area of oil and gas.The main oil-gas enriched zones are located in the abnormal high-pressure after hydrocarbon generation in large scale.

SEDIMENTARY FACIES OF MEMBER 2 OF SHANXI FORMATION OF LOWER PERMIAN IN THE MIDDLE-EASTERN ORDOS BASIN

Xing Housong, Xiao Hongping, Sun Fenjin, Xiao Jianxin, Liu Ruie, Zhang Chunlin, Lin Jie

2008, 30(4): 345-351. doi: 10.11781/sysydz200804345

Abstract(785) PDF-CN(465)

Abstract:
Sedimentary sequence and tectonic features of outcrops and cores in Member 2 of Shanxi Formation in the east edge of Ordos Basin are studied with modern sedimentary mechanisms.Rhythmic stratification,block stratification and lateral accretion cross stratification are widely found in outcrops and cores of Member 2 of Shanxi Formation.Outcrop sands are lenticular,cutting each other and piling to large sand belts,due to frequent migrations of braided-river sands.Based on studies of rock sedimentary facies,well logging sedimentary facies,sandbody thickness,palaeotopography and palaeogeologic background,it is pointed out that,when Member 2 of Shanxi Formation deposits,sandy braided-river and shallow water delta system is formed,which can be divided into alluvial plain braided-river,braided-river delta plain,braided-river delta front,frontal braided-river delta or seashore shallow lake facies from north to south.Braided-river main channel,alluvial marsh,delta front debouch bar are distinguished.Main sand belt with large width and thickness proportion in main channel of braided-river is favorable for petroleum exploration.

STUDY OF THE SEDIMENTARY CHARACTERISTICS AND HYDROCARBON ACCUMULATION RULES FOR THE GABON BASIN, WEST AFRICA

Liu Yanli, Qiu Chunguang, Xiong Liping

2008, 30(4): 352-356. doi: 10.11781/sysydz200804352

Abstract(985) PDF-CN(380)

Abstract:
A comprehensive study of the regional tectonic setting,sedimentary evolution and source reservoir cap conditions indicates that the Gabon Basin has experienced 3 evolutional phases: rifting period,transitional period and drifting period.The sedimentary strata of every evolutional phase are divided into 3 parts: pre-salt sequence,salt sequence and post-salt sequence.The main petroleum systems are the pre-salt and post-salt sequences.The post-salt petroleum system is distributed on the North Gabon sub-basin and pre-salt one is located in the South Gabon sub-basin.It makes clear the main sedimentary distribution of pre-salt and post-salt sequences and their controlment on source rocks and reservoirs.This paper summarizes the main factors of post-salt reservoirs are "reservoir controlled by fault scarp,traps controlled by salt,oil controlled by tectonic and traps" and the main factors of pre-salt reservoirs are "sources and reservoirs controlled by facies,caps controlled by salt,oil controlled by tectonic and traps".

STUDIES OF ACCUMULATION STAGES OF SILURIAN GAS-BEARING RESERVOIRS IN WELL KONGQUE 1 IN THE TARIM BASIN

Xiao Hui, Ren Zhanli, Cui Junping

2008, 30(4): 357-362. doi: 10.11781/sysydz200804357

Abstract(918) PDF-CN(308)

Abstract:
Oil and gas explorations in the northeast of Tarim Basin are quite successful recently with several commercial gas accumulations discovered in high and over-matured source region.The Kongque 1(Kq 1) Gas Field,situated in the Weimake-Kaiping Structural Belt of the Kongquehe Slope,is a representative gas accumulation.With applications of organic inclusions,accumulation stages of Silurian gas-bearing reservoirs in Well Kq 1 are determined.According to experiment results,charge history of Well Kq 1 can be divided into 2 stages.The first stage is the formation time of palaeo-petroleum reservoir in de-positional phase of late-Caledonian movement(350-365 Ma).The second stage is the gas formation time during tectonic uplifting stage(325-315 Ma).Gas is thermal cracked gas derived from palaeo-petro-leum reservoirs.Compared with accumulation time of Well Yingnan 2,formation time of Well Kq 1 is earlier.Late period accumulation characters in the Kongquehe area is not general.Different tectonic belts have different oil-and-gas accumulation histories.New cognitions about formation stages of oil-and-gas are important for further explorations in the Kongquehe area.

DISCOVERY OF INCISED VALLEY AND ITS PETROLEUM GEOLOGICAL SIGNIFICANCE AT CHEPAIZI AREA OF THE JUNGGAR BASIN

Li Tao, Lu Yongchao, Chen Ping, Xiang Kui

2008, 30(4): 363-366. doi: 10.11781/sysydz200804363

Abstract(744) PDF-CN(298)

Abstract:
Incised valleys have important petroleum geological significance.Discovery and systematic research of incised valleys in Tugulu Group of Lower Cretaceous at Chepaizi area of the Junggar Basin have shown that,the incised valley system can be divided into the eastern margin system and the southern margin system by the Chepaizi Uplift.The back bulge slope belt in large compressional basins is the major area where large incised valleys are formed.Multi-stages of erosion both vertically and laterally,and the following filling accumulation and lateral aggradation result in peculiar sedimental structure and filling characteristics of incised valley system.Rapid fall of lake level caused by strong episodic tectonic compression and thrusting in the southern margin of Junggar Basin during early Cretaceous leads to inside valleys.At present,the incised valley system is the main hydrocarbon exploration target in Chepaizi area.

EVALUATION OF THE EXCELLENT TRIASSIC TO SILURIAN MARINE HYDROCARBON SOURCE ROCKS IN XUANHAN-DAXIAN AREA OF NORTHEAST SICHUAN BASIN

Qin Jianzhong, Fu Xiaodong, Tenger

2008, 30(4): 367-374. doi: 10.11781/sysydz200804367

Abstract(841) PDF-CN(387)

Abstract:
Wells Puguang 5 and Maoba 3 were important in Xuanhan-Daxian exploration area in northeastern Sichuan basin,which supplied important evidence for the studies of the oil and gas accumulation conditions of this area.The organic geochemistry synthetic section was established by the data of TOC,chloroform bieuminous "A" and the hydrocarbon generation potential of the drilled marine sequences by wells Puguang 5 and Maoba 3.Synthetic analysis based on the organic geochemistry section,combining with regional geology information,indicated that there were two sets of excellent marine source rocks developed in the Triassic to Silurian strata of the area,i.e.the Upper Permian Longtan Formation black mudstones and carbargillite,and the Mid-Lower Silurian black mudstones.The solid bitumen occurred in Feixianguan oolite reservoir and Changxing biogenetic reef reservoir was characterized by thermal evolution origin,abundant contents and wide distribution,indicating that there were ancient oil pools in Feixianguan and Changxing reservoirs.The ancient oil pools were believed to be excellent secondary hydrocarbon generation source.Furthermore,the muddy limestone of Maokou Formation and the fuscous limestone of Qixia Formation were medium quality of source rocks.Existence of a lot of excellent hydrocarbon source rocks and secondary hydrocarbon generation source could supply abundant matters for the hydrocarbon accumulation in this area.

GEOCHEMICAL CHARACTERISTICS AND ORIGIN OF INCLUSIONS AND ADSORBED HYDROCARBONS IN YAOJIA FORMATION SANDSTONES IN QIANJIADIAN AREA, THE KAILU BASIN

Li Hongtao, Wu Shixiang, Cai Chunfang, Luo Xiaorong, Bao Rima

2008, 30(4): 375-381. doi: 10.11781/sysydz200804375

Abstract(1109) PDF-CN(290)

Abstract:
Inclusion hydrocarbons and adsorbed hydrocarbons were observed under microscope and UV fluorescence in Lower Cretaceous Yaojia Formation sandstones in Qianjiadian area,the Kailu Basin.Subsequently,these sandstone samples were washed,crushed,extracted for hydrocarbons and analyzed by GC and GC-MS.The results showed that ratios of C₂₉ ααα sterane 20S/(20S+20R) and C₃₁ αβ hopane 22S/(22S+22R) of the hydrocarbons were closed to respective equilibrium values,suggesting that the hydrocarbons were marginally mature to mature.Among C₂₇,C₂₈ and C₂₉ ααα20R steranes,C₂₇>C₂₈29.Ratios of C₂₅/C₂₆ tricyclic terpane and regular steranes/17αC_29-33 hopanes were relatively low.The values together with those of gammacerane index and homohopane index consistently indicated that the inclusion oils and adsorbed hydrocarbons were derived from humic-sapropel type organic matter under poor reducing freshwater to semi-saline environment.The features were similar to those of organic matter extracted from the Upper Jurassic Jiufotang Formation source rocks in the Kailu Basin.Thus,it could be concluded that the inclusion oils were mainly derived from the Upper Jurassic Jiufotang Formation source rocks of lacustrine facies.

THERMAL SIMULATION OF HEAVY CRUDE OIL FROM WELL S74 IN THE TARIM BASIN (Ⅱ)——HYDROCARBON GENERATING POTENTIAL OF BITUMEN

Liu Guangxiang

2008, 30(4): 382-385. doi: 10.11781/sysydz200804382

Abstract(1014) PDF-CN(329)

Abstract:
The hydrocarbon productive rate of the degradation-oxidant bitumen were discussed based on the geochemical characteristics of the simulation products and the hydrocarbon productive rate at various simulation temperature points of the heavy crude oil from Well S74 in the Tarim Basin.The results indicated that hydrocarbon-generation of the degradation-oxidant bitumen was mainly taken place in the oil-generating window,in other word,oil was mainly generated when R_o was not larger than 1.24%(T=350℃),with its oil productive rate of 245 kg/t.There also was some hydrocarbon-generating potential in the highly-matured bitumen,but almost no hydrocarbon-generating potential in the over-matured bi-tumen.Their products were mainly alkane gas.According to above model,hydrocarbon generation amount of the Silurian bitumen sandstones in the Shaya and the Katake Uplifts was calculated.It showed that the generated hydrocarbon was magnitude and probably was one of important sources for hydrocarbon accumulations since the Late Hercynian in the Tarim Basin.

STUDY OF BIODEGRADATION EFFECT ON AROMATIC BIOMARKER PARAMETERS

Ni Chunhua, Bao Jianping, Gu Yi

2008, 30(4): 386-389. doi: 10.11781/sysydz200804386

Abstract(976) PDF-CN(504)

Abstract:
In most cases,biodegradation is the main factors which cause the crude oil sticky.At present,biodegradation effect on saturated hydrocarbon biomarkers,nitrogen compounds and their parameters is mostly studied,with less attention is paid to the research of aromatic biomarker parameters.Four oil samples with different degraded degrees in Bozhong Sag of the Bohai Bay Basin are selected.By using GC-MS tests,the biodegradation influences on some aromatic biomarker parameters in crude oils especially on maturity indicators under natural conditions is preliminarily discussed.The results indicate that the maturity of oil degradation calculated by using methyl naphthalene ratio(MNR) is less than that before degradation,and the maturity calculated by using methyl phenanthrene ratio(MPR) is larger than that before degradation.However,the maturity of oil degradation calculated by using triaromatic steroid/monoaromatic sterane(TAS/MAS) ratio is basically undistortion.

HYDROCARBON-REGENERATION CAPABILITY OF MARINE PALEO-RESERVOIR AND SOLUBLE ORGANIC MATTER

Zheng Lunju, Wang Qiang, Qin Jianzhong, He Sheng

2008, 30(4): 390-395. doi: 10.11781/sysydz200804390

Abstract(712) PDF-CN(277)

Abstract:
Based on the results of thermal simulation of many samples at conditions of close system,the hydrocarbon-regeneration capabilities and yield distribution features of soluble organic matter and marine paleo-reservoir which has different properties and different compositions(extra heavy oil,normal crude oil and light oil) were studied.The results indicate that the hydrocarbon-regeneration capability of different marine paleo-reservoir and soluble organic matter were ranked in order of condensate oil light oilnormal crude oilSilurian asphaltic sandstones≥heavy oil limestone≥low-mature solid bitumen≥asphalt-bearing limestoneheavy oil sandoxidation solid asphalt.This capability was mainly controlled by the properties and compositions of soluble organic matter besides factors of lithology,occurrence state and evolution degree.Hydrocarbon-regeneration process of soluble organic matter was continuation of hydrocarbon generation from kerogens.The hydrocarbon generation potential of soluble matter was equivalent with that of kerogens.They could be used as light oil or natural gas source when their temperature arrived at over-high mature stages.

AN APPROACH TO ESTIMATION OF THE POTENTIAL LOSS OF SECONDARY HYDROCARBON GENERATION FROM THE CARBONIFEROUS——PERMIAN COAL DURING SIMULATION EXPERIMENTS

Zhang Xinguo, Miao Jiujun, Xu Liangfa, Guo Dixiao

2008, 30(4): 396-399. doi: 10.11781/sysydz200804396

Abstract(692) PDF-CN(258)

Abstract:
Why there would always be inconstancy between the loss of hydrocarbon generation potential and the D-values derived from the total hydrocarbon generation and expulsion from coal? A series of simulation experiments on secondary hydrocarbon generation from the Carboniferous-Permian coals may give the answer.It is probably caused by the great proportion of unstable non-hydrocarbons and asphaltine in degradable substances,the considerable part of which was transformed into insoluble organic matters or other non-hydrocarbons during evolution,resulting in D-values between expelled hydrocarbons and loss in hydrocarbon generation potential.Thus the current conception to account the loss in hydrocarbon generation potential as the value of hydrocarbon generation and expulsion should be corrected,while making resources evaluation.

CHARACTERISTICS OF SEDIMENTARY FACIES RESPONSE TO THE SEISMIC WAVE——AN EXAMPLE OF THE 3RD MEMBER OF SHAHEJIE FORMATION IN THE GUNAN SAG OF THE BOHAI BAY BASIN

Lai Shenghua, Pu Xiugang, Du Guirong

2008, 30(4): 400-404. doi: 10.11781/sysydz200804400

Abstract(687) PDF-CN(293)

Abstract:
According to the seismic waveform theories,the seismic facies have been identified and divided automatically and the plane distribution of the depositional systems have also been determined.Compared with the traditional methods,this method has the advantages of saving time,more objective and more accuracy.Using this method,the plane distribution of the depositional system of the middle part of middle submember of the 3rd member of Shahejie Formation has been studied in Gunan Sag of the Bohai Bay Basin.There is preferable relationship between the seismic facies models and the sedimentary facies,and at the same time,they are sensitive for sedimentary facies changes,therefore,can be used for microfacies division.It indicates that three depositional systems,including braided-river delta,basin floor fan and lake depositional system,were existing in the Gunan Sag at this time.The front subfacies of the braided-river delta was developed in the south slope of Gunan Sag.The basin floor fan was mainly distributed in the north of the sag,located in basal slope of the Gunan fault.In addition,the slump of the nearshore strand bar also can form basin floor fan complex.In this period,the nearshore strand sandstone bar and sheet are more abundant.

GC-MS QUANTITATIVE ANALYSIS OF BIOMARKERS

Zhang Zhirong, Song Xiaoying, Zhang Qu

2008, 30(4): 405-407. doi: 10.11781/sysydz200804405

Abstract(730) PDF-CN(458)

Abstract:
Added Internal standard sample to the saturated hydrocarbon fractions which are obtained through silicon-alumina column chromatography in crude oil or extraction asphalt "A",then carried out the GC-MS quantitative analysis of biomarkers.The results indicate that quantitative analysis errors of the steranes and hopanes are less than 10%.This method is applied to the GC-MS quantitative analysis of biomarkers for expulsive oils during thermal simulation of rocks.The results show that the contents of biomarkers gradually decrease with the rising of simulation temperature,but the situation is basically stable after 350℃.The ratio of Ts/(Ts+Tm) increases with the rising of simulation temperature.

SEISMIC MULTI-PARAMETERS ANALYSIS AND EVALUATION OF LITHOLOGIC TRAPS

Jiao Zhifeng, Yang Zhanlong

2008, 30(4): 408-413. doi: 10.11781/sysydz200804408

Abstract(1054) PDF-CN(237)

Abstract:
In view of the complexity in boundary condition,irregularity in shape and subtle in occurrence of lithologic traps,a practical approach of identification,preference,description and evaluation of lithologic traps is put forward in this paper,which is the multi-parameter analysis of seismic data based on sequence stratigraphy and "three facies" integrated interpretation.This method mainly includes seismic facies analysis,seismic inversion and reservoir prediction,seismic attributes analysis,fluid potential analysis and hydrocarbon detection,3-dimensional visualization etc.The applications in Banghu area of the Jianghan Basin and Shengbei area of Turpan-Harmy Basin preliminary show the effectiveness and practicability of this approach in identification,preference,description and evaluation of lithologic traps.The practical shows that this approach is suit for lithologic reservoir exploration of the area with good quality of seismic data,simplicity in structure and medium or matured exploration area.And the selection of seismic data,definition of the size of time-widows for analysis,interpretation of top and bottom constraint horizon,optimization of seismic attributes in different frequency band are the key points for this approach.

INDEX TRANSLATION AND EVALUATION METHOD OF OVERPRESSURE IN DEEP FORMATION OF SEDIMENTARY BASIN——A CASE STUDY AT THE BOUNDARY AMONG HUNAN, GUIZHOU, HUBEI AND CHONGQING

Feng Changmao, Wu Chonglong

2008, 30(4): 414-419. doi: 10.11781/sysydz200804414

Abstract(940) PDF-CN(272)

Abstract:
Overpressure in sedimentary basins can be summarized into 3 types: disequilibrium compaction function,tectonic extrusion and liquid function.The forming mechanism includes undercompaction,montmorillonite dehydration,hydrocarbon generation,hydrothermal pressurization and hydrocarbon cracking,etc.But in deep formations,overpressure is mainly related to hydrothermal pressurization,superjacent strata pressure,hydrocarbon generation and cracking.So,overpressure coefficient in deep formation can be transformed by adding hydrothermal pressurization coefficient,superjacent strata coefficient and hydrocarbon pressurization coefficient.To estimate overpressure developed area,faults should be taken into consideration.Overpressure of the Lower Cambrian Niutitang Formation at the boundary among Hunan,Guizhou,Hubei and Chongqing has been studied.The most favorable region for overpressure locates around Yibin.

A METHOD FOR EXTRACTING CHARACTERISTICS OF IMAGE TEXTURE AND IDENTIFYING OF CUTTINGS BY FOURIER TRANSFORM

Wang Dongqiang, Li Wendong, Liu Zonglin, Ci Xinghua, Yang Xiaoming, Zheng Ronger

2008, 30(4): 420-423. doi: 10.11781/sysydz200804420

Abstract(761) PDF-CN(278)

Abstract:
In the process of logging,it's quite slow for human eyes to identify the cuttings made by the PDC bit.In order to extracting characteristics of cuttings' image texture effectively,using the algorithm of circular Fourier spectral energy,the image's spectral energy in different frequency ranges is classified.Hence the distribution ratio of the spectral energy is calculated and taken as the characteristic.With the basis of the results of artificial identifying,the characteristics of the standard samples are taken as the training characteristics to test the ones of the random samples using Bayes classifier in the identifying process.The reliability of the method is also tested.It proved that the method was relatively good to analyze the character of cuttings with an identifying accuracy 99.44% for mudstone.

PHYSICAL MODELING ON DOUBLE DECOLLEMENTS STRUCTURE IN FOLD-AND-THRUST BELT

Liu Yuping, Yin Hongwei, Zhang Jie, Xu Shijin, Xie Guoai

2008, 30(4): 424-428. doi: 10.11781/sysydz200804424

Abstract(747) PDF-CN(389)

Abstract:
Fold-and-thrust belt is an important component in orogen-foreland basin system.Decollement plays a remarkable role in its formation and development.In order to study geometric and kinematic characteristics of fold-and-thrust belt which has 2 decollements with different thickness and position,a series of scaled physical modeling experiments have been done.Deformations of models with shortening increase are photoed.In fold-and-thrust belt with 2 decollements,forward thrusts which propagate from the lower decollement form the main thrusts,and their development obeys forward pattern.In the hanging wall of thrust,rock layers bend above the upper decollement and form fault-related fold.When the 2 decollements are close to each other,they work together and control thrust development,forming less forward thrusts,yet favorable for backward thrusts.While they are widely spaced,the lower decollement mainly controls thrusts development.More forward thrusts and less backward thrusts are formed.

2008, 30(4): 999-999. doi: 10.11781/sysydz200804318

Abstract(544) PDF-CN(286)

Abstract:

2008 Vol. 30, No. 4

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