Study of tempestite sedimentary of Paleogene in Huimin depression

By means of core observation,thin-section analysis,granularity analysis and log analysis,the tempestite sedimentary of Paleogene in Huimin depression was studied.Nine kinds of tempestite sequences and four sedimentary models such as autochthonous coarse grain rocks,near source tempestite A,near source tempestite B and distal tempestite were summarized according to vertical sequence types, structures and sediment characters.The distribution rule of tempestite was also summarized.The results indicate that the tempestite in the area has lots of rock types including clastic rocks,bioclastic limestones and volcaniclastic rocks.The cumulative probability plots have high slope-multi-bouncing population-1 suspension population pattern,multi-segments pattern and high slope 1 segment pattern.The sedimentary structures include gutter cast,surface of scour, cut structure,graded bed,massive bedding,hummocky cross stratification(HCS),parallel bedding,ripples,contemporaneous deformation and Fugichnia.The grains distribution and sedimentary structures show that the transportation medium is characterized by tractive current and gravity flow synchronously.The tempestite and non-tempestite occur alternately in vertical section.The development of tempestite is related to stratum,ancient landform and water depth,tectonic location and clast supply.The tempestite is encircled by non-tempestite in horizontal section.The tempestite became(fan) delta,beach bar toward the shallow water,and became turbidites or(half) deep lake clay stone towards basin.