The Manto Type Limestone Replacement Deposits of Northern Mexico

limestone deposits, Los Lamentos district, Santa Eulalia district, Mapimi district, Texas Comanchean formation, dolomitization

Patterson, John Wilfred ; Buwalda, John P.

University:California Institute of Technology

Department:Geological and Planetary Sciences

关键词: limestone deposits, Los Lamentos district, Santa Eulalia district, Mapimi district, Texas Comanchean formation, dolomitization;   

Others  :  https://thesis.library.caltech.edu/10616/73/Patterson_jw_1932.pdf

美国|英语

来源: Caltech THESIS

【 摘 要 】

A study has been made of the principal manto type limestonereplacement deposits of northern Mexico. Three of the districts, Los Lamentos and Santa Eulalia in Chihuahua, andMapimi in Durango, are described in detail. The sedimentaryrocks are correlated with the Texas Comanchean formations.The ore deposits are confined to certain beds of Upper Trinity and Lower Fredericksburg age. Data show that it is the physical and not the chemical properties of the limestonewhich make some beds more susceptible to replacement thanothers.

Folding and fissuring have been essential in localizingthe ore deposits. Mantos have been found to occur, ingeneral, in favorable beds at the crests of folds. Thefissure zones are most pronounced in depth. The cross sectionof a deposit decreases upward from the apparent source althoughthe diminution is not constant. Mantos have yielded most ofthe ore in the upper deposits; chimneys become more importantin depth. The analyses of sections of an ore body areuniform but the deposits show a gradual change in composition ina district. The ores are zoned vertically and laterally fromthe apparent source and are believed to have been depositedby magmatic waters. The principal deposits of a district were formed at one time. The metallic content of the beddedoxidized deposits is almost identical to that of the primarydeposits from which they were derived. Dolomitization hasoccurred locally during oxidation.