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格兰茨地区的铀矿床主要产于侏罗纪莫里森建造上部的陆相砂岩中,少数具有重要价值的矿床产于侏罗纪托迪耳托建造的灰岩和白垩纪达科他建造的黑色页岩中,形成了几百吨到几百万吨储量的带状矿体(runs)。矿石主要成分为:品质铀矿、含铀碳质物、铀石以及钙钒铀矿、钒钾铀矿和硅钙铀矿等次生氧化矿物。在砂岩中,带状矿体的分布局限于泥岩、填隙碳化物和原生砂河道方向,在灰岩中,矿石沉积与褶皱和破裂带有关。格兰茨地区的安布罗西亚湖矿山和拉古纳地区的杰克派尔以及帕瓦蒂矿山开采了大量的铀矿石。矿石的 U_3O_8含量一般为0.20—0.30%。在侏罗纪主岩沉积后,在地质史上还发生了翘起、断层、侵蚀、地下水环境改变和氧化等过程,这些过程大大影响了矿床的产状和特点。矿床成因比较复杂。比较一致的看法是:原生带状矿体属于前达科他期。在安布罗西亚湖还识别出两个主要矿石形成阶段,这两个阶段是以拉拉米断层活动为界。全部早期形成的矿石在第四纪被氧化、溶解并重新富集,在此阶段内形成了许多次生钙钒铀矿、准钙钒铀矿和钒钾铀矿。
The uranium deposits in the Grants area are mainly found in continental sandstones that were built in the upper Jurassic Morrison. A few of the most valuable deposits originated from the limestone built in the Jurassic Torreidoros and the blacks built by the Dakota of the Cretaceous Shale, the formation of hundreds of tons to millions of tons of banded ore reserves (runs). Ore main components: quality uranium, uranium-bearing carbonaceous matter, uranium and calcium-vanadium uranium ore, vanadium potassium uranium ore and secondary calcium silicate-uranium ore minerals. In sandstone, the distribution of banded orebodies is confined to the direction of mudstone, interstitial carbides and primary sand channels. In limestone, ore deposits are related to folds and ruptures. The Amblesia Lake mine in the Grants area and the Jack Piel and Parvati mines in the Laguna area mined lots of uranium ore. U_3O_8 ore content is generally 0.20-0.30%. After the Jurassic host rocks were deposited, processes such as tilting, faults, erosion, changes in the groundwater environment and oxidation occurred in the geological history. These processes greatly affected the occurrence and characteristics of the deposit. Genesis of the deposit is more complex. A more consistent view is that the primary banded ore body belongs to the pre-Dakota period. Two major ore formation stages have also been identified at Amblesia Lake, both of which are bounded by the Laramie fault. All of the early formed ores were oxidized, dissolved and re-enriched in the Quaternary, during which many secondary calcium-vanadium uranium deposits, quasi-calcium-vanadium uranium deposits and vanadium-potassium uranium deposits were formed.