Changes

The Yanchang Formation of the Upper Triassic is a suit of terrestrial fluivolacustrine-deltaic sequence, consisting one of the main hydrocarbon-producing intervals in the area. The Upper Triassic Yanchang Formation can be divided into three facies from the bottom to the top.

The Yanchang Formation of the Upper Triassic is a suit of terrestrial fluivolacustrine-deltaic sequence, consisting one of the main hydrocarbon-producing intervals in the area. The Upper Triassic Yanchang Formation can be divided into three facies from the bottom to the top.

(Figure 10).

(Figure 10).

 

[[File:Sandstone-Fig-10.png|thumb|300px|Figure 10: Typical stratigraphic section of the Lower-Middle Jurassic and Upper Triassic fluvio- deltaic facies showing general lithostratigraphy and sedimentary structures 1). 1, [[Oil shale]]; 2, trough [[cross-bedding]]; 3, tubular cross-bedding; 4, parallel bedding; 5, ripple cross-bedding; 6,contorted bedding; 7, [[conglomerate]]; 8, gravel sandstone;; 9, sandstone; 10, silt; 11, muddy sandstone; 12, muddy silt; 13, silty mudstone; 14, mudstone. (Modified after Luo Jinglan et al, 2002).]]

[[File:Sandstone-Fig-10.png|thumb|300px|Figure 10: Typical stratigraphic section of the Lower-Middle Jurassic and Upper Triassic fluvio- deltaic facies showing general lithostratigraphy and sedimentary structures 1). 1, [[Oil shale]]; 2, trough [[cross-bedding]]; 3, tubular cross-bedding; 4, parallel bedding; 5, ripple cross-bedding; 6,contorted bedding; 7, [[conglomerate]]; 8, gravel sandstone;; 9, sandstone; 10, silt; 11, muddy sandstone; 12, muddy silt; 13, silty mudstone; 14, mudstone. (Modified after Luo Jinglan et al, 2002).]]

===Evolutional diagenesis.===  

===Evolutional diagenesis.===