Discussion on estimate method of structural fracture volume and abundance based on field geological survey:A case of Block A in Lancang County,Yunnan Province
The development pattern and prediction of structural fractures are a fundamental research content for various mineral and geothermal exploration,and the development pattern of structural fractures is diverse and complex in outdoor outcrops.To explore the volume and abundance of structural cracks influenced by faults,the author carried out a field geological survey,data statistics,and calculation in Block A of Lancang County,and the geological exploration level was extremely low there.The author has reached the following conclusion:1)The rock type can affect the density of structural fractures,that is,compared with magmatic rock and metamorphic rock,the density of structural fractures in sedimentary rock is larger and the spatial distribution of structural fractures in sedimentary rock is more regular;2)The structural fractures is obviously controlled by faults,that is,there is a negative correlation between distance from faults and the density of structural fractures;3)There are different lateral influence ranges of structural fractures in normal faults,thrust faults and strike slip faults,of which the influence range of strike slip fault is about 1 km;4)In the process of theoretical calculation,the simplification of some complex geological problems(including heterogeneity between different layers,complex areas of multiple faults,changes in the occurrence of faults in the deep,etc.)may result in certain errors in the calculation results.Guided by the above achievements,the author calculated and obtained that the number of internal structural fractures in Block A is 7 458×107,the volume of structural fractures is 7 458 × 104 m3,the plane abundance of structural fractures is 186.45 ×104 m3/km2,and the volume aboundance is 186.45×104 m3/km3,which has certain reference value for the exploration and development of fluid energy minerals(such as oil,natural gas,geothermal,etc.)in this area.
structural fracturevolumeabundancefield geological surveyLancang County
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