Macroscopic and mesoscopic development characteristics of the top strata of Middle Ordovician limestone in the Hanxing mining area

In order to understand the source of groundwater inrush and its hydrogeochemical evolution path truly, determine the evolution characteristics and development trend of water cycle, and effectively solve the problem of water disaster in mining area. In this paper, Jiaozuo mining area, a typical large water mining area of North China type, is selected as the study area. Taking the Ordovician aquifer in the study area as the research object, the Ca2+ hydrochemical equilibrium model of Ordovician limestone water system is established by analyzing the characteristics of concentration gradient field and the relationship between the hydrochemical ions (Ca2+、K++Na+、Mg2+、Cl-、SO42-、HCO3-) and TDS in the mining area, it made a systematic study on the characteristics of Ordovician limestone water circulation, and analyzed the recharge, runoff and discharge characteristics of groundwater in different areas of the mining area. The results show that the Ordovician limestone water in the Jiaozuo mining area has a weak leaching effect in the north and southwest, but a strong leaching effect in the southeast, which shows a runoff characteristic from the north and southwest to the southeast.

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FABRIC OF A MIDDLE ORDOVICIAN LIMESTONE AT COLBORNE, ONTARIO

Canadian Journal of Earth Sciences ◽

10.1139/e67-028 ◽

1967 ◽

Vol 4 (3) ◽

pp. 529-540

Author(s):

P. J. Lee ◽

C. G. Winder

Keyword(s):

Factor Analysis ◽

Marine Environment ◽

Environmental Influence ◽

Ordovician Limestone ◽

Middle Ordovician ◽

Sedimentary Structures ◽

Carbonate Sedimentation ◽

Convex Upward ◽

Quartz Grains

The varieties of limestone in the Middle Ordovician Cobourg Formation at Colborne, Ontario occur as follows: sparse biomicrite, 49%; fossiliferous micrite, 26%; biosparite, 23%; micrite, 2%; and packed biomicrite, trace.Some individual beds display a sequence of sedimentary structures composed of graded bedding at the base, followed by a zone of lamination, and structureless micrite at the top. Most disarticulated brachiopod and ostracod shells are convex upward in biosparite and convex downward in biomicrite and fossiliferous micrite. The percentage of brachiopod shells decreases towards the top of the quarry and changes laterally. Mechanical orientation patterns of elongate fossils show two dominant trends, NE–SW and NW–SE. Factor analysis suggests that the association of brachiopod shells and pelmatozoan fragments was controlled by a common environmental influence, that the bryozoa and ostracod remains were transported together with reworked quartz grains, whereas the distribution of trilobite fragments was controlled by another condition.The carbonate sedimentation occurred in a marine environment of generally low turbulence. Stronger currents were introduced sporadically to form graded and non-graded biosparites.

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