Saskatchewan Marine Potash Deposits' Characteristics And The Exploration & Development Of Potash

Soluble potash is one of three essential fertilizers for crops,while the others are nitrogen and phosphate fertilizer.About 95% of potash is used for fertilizer.China's proven potash reserve has increased to 140 million tons after many years' prospecting.As the biggest consumer,China is highly depending on importing potash from overseas.More measures should be implemented to maintain the reasonable price and to guarantee the supply.But potash resource is still monopolized by limited countries.There is the largest potash deposit in Elk Point basin in Saskatchewan,Canada.Specifically,the potash deposit sits in Saskatchewan sub-basin and it is famous for its huge scale,impressive thickness of potash members,high grade and great purity.The thesis is taking the potash deposit in Elk Point basin as the object of research.Main works completed in KP488 include 86.6km of 2D seismic lines,96km2 of 3D seismic survey,7 drilling wells in total depth of 9722.7m and 1382 core samples' analysis.It also combines the author's 8 years working experience on the project and plenty of regionally geological data.The thesis tells the geological structure,the origin and characteristics of Saskatchewan potash deposit.It also gives some idea about what make marine basins deposited here by comparing Saskatchewan potash basin with other marine basins in the world.Besides,the author makes an exploration mode for prospecting potash beds sitting in deep stratum.Moreover,the author gives his own experience and thoughts on how to develop a potash mine in Canada and hope this helpful to Chinese enterprises that plan to develop mineral projects overseas.The research of potash deposit in Elk Point basin tells that factors making Saskatchewan potash deposit includes multiple transgressive cycles and regressive cycles,the geological structure of multiple marine basins and marine platform basin short of water supply.Multiple transgressive cycles and regressive cycles and the structure of multiple marine basins could result from the move of palaeoequator and paleoclimate cycle.Palaeogeography and paleoclimate helps lots of salt deposited in several sub-basins in Elk Point.After that,potash accumulated in Saskatchewan subbasin.To sum up,the unique structure,palaeogeography and paleoclimate jointly made Saskatchewan potash deposit accumulated.The development of the basin went through two phases of depositions and formations.The first is the period of passive continental margin from Cambrian to middle Jurassic period in which characteristic debris units deposited at the bottom and the deep-bed of carbonatite and evaporite overlain.While the second is the phase of polymerization between middle Jurassic and Eocene in which foreland basin took shape due to lots of debris coming from the rising Cordilleran Mountain Belt.Continental North America is centered of the Shield and Craton and sorrounded by Phanerozoic orogenic belt.Canadian Shield is the cornerstone of Continental North America while the Great Plain,the Colorado plateau and Hudson Bay are formed in the central North America platform.The shield,the platform and the base altogether constitute the North America Craton.Saskatchewan potash deposit is marine evaperite beds grown on a stable craton.Its northeast part sits on the Canada Shield,which is very stable.And its west is adjacent to the Canada Basin.Seawater started to pour into Elk Point basin in Devonian period while North America Platform started to subside and the sea level went up.The transgression advanced spirally in northwest–southeast direction.There were several transgressive cycles and regressive cycles presenting during the period and multiple marine basins migrated and deposited.Finally,a huge scale marine potash deposit was formed.Elk Point basin was surrounded by stable geological structure,while transgressions and regressions did not stay in stable status.Potash was born in the unique environment.However,lots of potash deposits present in stable area which is surrounded by unstable geological structures.To sum up,the best geological structure to deposit potash beds is either in unstable area surrounded by stable geological structure or in stable area surrounded by unstable geological structure.This principle might help to the marine potash prospecting in China.By the research and analysis of 7 drilling wells' stratigraphic sequence and the comparison with stratigraphic sequences of surroundings,the Upper to Middle Devonian strata of Saskatchewan sub-basin would be devided into 4 salt cycles.Potash is only present in the upper 60 m strata in Middle Devonian Elk Point group of the 1st cycle.The system of salt cycles could provide some clues to marine potash prospecting.There are lots of anomales in Saskatchewan potash deposit,such as salt removal,collapse and underlain Winnipegosis Mound.Through summarizing seismic and drilling data,collapses are classified into 4 classes according to their varying influence area,depth and structure.This would help to better identify anomalies.There is very good chance for Winnipegosis Mound to making overlain Prairie Evaperite thinner.However,potash members usually present in upper part of Prairie Evaperite.Thus,Winnipegosis Mound may only have limited impact on potash members.Collapses and salt removals are mostly coming from regional structure change and underground water.Davidson evaperite of Souris River in Manitoba group is close to Prairie Evaperite in geological sequence.Davidson evaperite could be used as a prospecting guide for speculating the presence of underground water and salt removal.We could asuume that there might be good chance having very good salt and potash deposit if there is continuous Davidson present.Good Patience Lake and Belle Plaine potash members are proven in KP488 by seismic data,core analysis of 7 drilling wells and logs data.Its grade and quality is similar to resources in currently operating potash mines in Saskatchewan,as well as its geological sequence.But potash in KP488 presents deeper.Works in KP488 tells more potash presenting in Saskatchewan.The most popular ways prospecting salt and potash are surface sampling and drillings.But the method does not work for marine potash beds deposited in deep strata because high cost and low efficiency.Seismic survey and downhole logs have improved a lot in pass several years.The author suggest a prospecting system for finding deep marine potash resource,which is to be more dependent on 2D and 3D seismic surveys and downhole logs while saving cost on fewer drilling wells.This will bring down prospecting cost and bring up efficiency.The format of geological report in North America is quite different from China.The author provides some guidance about the format of geological report in North America,which could help us to know both formats and understand each other better.The author spent 8 years working on KP488 project,from initial prospecting,acquiring mineral permit to detailed exploration.Lots of personal experience and local historic data are summerized in ths thesis,such as the origin of Saskatchewan potash deposit,local geology,advancing the potash project,stratigraphic sequence,charateristics of collapses,seismic survey,and so on.I hope this could give a hand to prospecting marine potash resource in China.By researching into KP488 project and other overseas potash projects operated by Chinese companies,the author is trying to give some idea about how to run potash projects overseas.The thesis could be helpful to Chinese companies building up potash mines overseas and secure potash supply to China.