| For many years,scholars from various countries in the study of periglacial geomorphology have paid great attention to determine the formation mechanism of the modern periglacial process.Because it is closely related to economic construction,and the formation environment and conditions of the periglacial landform,the microscopic physical and chemical process essence can be presumed.The causes and formation process of ancient periglacial landform can be determined,the reconstruction of Quaternary environment and prediction of the evolution of climatic environment,etc.can be rebuilt,and the combination form,morphological distribution,formation process and its causes of the periglacial landform are analyzed by scientific methods and technical means,and the quantitative description of them is carried out as far as possible,which greatly promotes the research progress of the periglacial landform.Laoheishan mountain is the second highest peak in the southern part of the hilly area of Eastern Liaoning Province.The highest elevation is 1029.4 meters.It is located in the seasonal frozen soil area.The coldness is far less than that of the permafrost regions in the northwest and northeast,but it has the conditions for the formation of periglacial landforms.Under the influence of freezing and thawing cycles,lithological characteristics,tectonic activities and other factors,the periglacial landform is developed and unique,and it is the southernmost periglacial landform discovered in the mountains of Eastern Liaoning Province.Through field investigation on the periglacial landform of the main peak of Zhuanghe Laoheishan mountains,a field investigation of its landform type,shape and distribution characteristics reveals that the rock sea of periglacial landforms in the Laoheishan mountain is widely distributed on the northwest slope of its main peak at an altitude of 700-800 meters;the rock rivers are mainly distributed in the hillside gullies with lower elevations,and the rock slopes are widely distributed on the steep slopes.Applying geographic information and remote sensing software for data processing,gravel fabric measurement and other methods,periglacial landform of Laoheishan mountain can be comprehensively analyzed,and the uniqueness of the rock sea landform in Laoheishan mountain can be found.The scale of the rock sea landform in Laoheishan mountain is large,which is 300-400 meters long and 100 meters wide.The gravel ridge is extruded and stackedoverhead,the overall height is 1-2 meters above the slope and the typical push-type boundary is especially obvious.The results of gravel fabric analysis indicate that the distribution is irregular,the piles are disorderly,the gravel is not sorted,the size is different and unstable,and the stability is determined by the extrusion stacking between gravels.There are unique features such as large gravel blocks in the rock sea area,relatively regular shapes,and elevated uplifts without vegetation cover.The damage mechanics and fracture mechanics theory are used to establish the frozen-thrust damage of jointed rock mass.The analysis can explain the formation mechanism of the unique geomorphology of Laoheishan periglacial landform,and analyze the influencing factors such as freeze-thaw,lithology and structure in the study area.It can be concluded that the ice sheet topography of Laoheishan mountain is mainly dominated by the freezing and weaving and wedging process,followed by the freezing and cleaving process.Due to the overall instability of the rock sea,the gravel rock is found in the upper part of the gravel.The re-crushing of the block indicates that the climatic conditions of the periglacial landforms in Laoheishan region are qualified.The freezing and thawing process under the freezing and thawing cycle is the decisive mechanism of its formation process.It is controlled together with the lithological factors and structural factors of the study area,and affects the formation process of the periglacial landform in Laoheishan mountain.Sample and analyze the bedrock of the main peak of Laoheishan mountains,which is a medium-thick feldspar quartz sandstone with siliceous cementation,hard in texture and prone to brittle fracture.Due to the control of lithological factors,the parallel bedding of surface bedrock in the study area is widely developed,and the water enters into it to freeze and form thin sheet ice bodies,which is conducive to the process of freezing and cracking,and forms thick layered blocks with smooth surface.Under the control of tectonic factors,the study area is located in the stress field of north-south torsion,and conjugate x-type joints are developed.The rock mass is cut into a diamond or checkerboard shape.Under the action of freeze-thaw,the rock is destroyed along the joint surface,and thick layered gravel blocks of different sizes,diamond or rectangle are formed. |
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