It is the coalfield of later Jurassic Epoch in the east of the coal gathering area of Northeast China, which is located in Jixi City and Jidong County of the east of Heilongjiang, and stretch to the three counties-Mishan,Muling and Linkou and has the area of 34 km².And the coking coals are the main products.
1.Geological Structure
The coal system of later Jurassic Epoch was formed in the immense inshore old geographical condition .Through the changes in the Mesozoic Era ,some of it was reserved in Jixi Coalfield in the form of fault and wide and gentle fold. The base of the coalfield is Mashan Group of the middle and later Proterozoic Erathem and exposed in the outside .The Pingma Reverse Fault which is from east to west divided the coalfield into two parts: the north is a syncline which is from east to west, and whose north wing gentle and south steep. The wing part consists of coal system and the axis belongs to the later Cretaceous Period; the south is a monocline which tilts towards southeast. There are sub-syncline and sub-anticline .And it consists of coal system and the coals of later Cretaceous Period .The magmatic movement in the later Mesozoic period didn’t influent the coalfield very much, and only some diorites appeared in the Zhangxin Coalmine, irrupting some sections of the coal seam as the rock bed.
2. Coal System
The coal bearing stratums whose depth is from one hundred meters to two thousand meters mainly belong to land facies, and one to two of which are coastal sedimentation. It is called Jixi Group and may belong to either later Jurassic Epoch or early Cretaceous Epoch. The Jixi Group can be divided into three parts, and from down to up they are:
Didao Formation.It consists of sand stones, mudstones, coal mudstones and several thin layers of coal .In regional parts, there are andesites and lump stones. The Formation is 0-400m deep.
Chengzihe Formation. It consists of conglomerates, sand stones, mudstones, tuffs and coal seams .The Formation is 70-1100m deep.
Muleng Formation .It consists of conglomerates, sand stones, mudstones and coal seams. There are many layers of tuffs and tuff quality .The Formation is 150-900m deep.
Chengzihe Formation and Muleng Formation are the main coal bearing strata of Jixi Coalfield. The coal bearing stratum of Chengzihe has 7-40 layers, among which, 3-17 layers are minable.The coal seams increase from west to east, and the average minable depth is 9.95m.Muleng Formation has 10-17 layers of coal bearing strata, among which,2-7 layers are minable.The coal seams decrease from west to east, and the average minable depth is 5.65m.Around Honghuo ,the east of Jixi coalfield, it belongs to new Tertiary System, where contains the seams of brown coal and some are minable.
3. Coal resources
The amount of coal resources in Jixi Coalfield is about 17GT and 3Gt are proved. They are mainly 1/3 coking coals, and the other are coking coals, fat coals, lean coals, weakly caking coals and long flame coals. The quality is middle ash and low sulfur, suitable for making coke.
4. Mining Condition
They are mainly thin coal seams, some of which are middle thick seams. The dip angle is gentle and the complex level of the structure is middle. The hydrological and geological conditions are simple, belonging to hard crevice water filling deposit. Most of the producing shafts are high gas ones ,a few are low gas and partial are gas outburst ones. The coal seams haven’t the trend of spontaneous combustion, but there are more dangerous about coal dust explosion. The gradient of earth temperature is high, influencing the mining in the depth of the coalmine.
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