Salt Lake Mining Review | 1905-02-28 | Page 3 | The Deer Trail Mine near Marysvale, Utah

the deer dee r trail mine near marysvale Marys vale utah actual and speculative conditions unlike other othe r personal and private property the P public bublic and individuals assume tho the I 1 prerogative of discussing the merits and de nie merites rites of mining property notwithstanding the general assumption of right there is some conle hesitancy on the part of the writer C B Q W in attempting to dissect the somewhat complex geological conditions that maintain in the famous old deer trail up in piute county utah without first begging the pardon of the well known salt lake owner for this seemingly unwarranted intrusion on his personal rights however the misgivings are somewhat modified by the fact that the portals of the capacious interior of the deer trail are wide open to the public it was about the year 78 when the deer trail was discovered the almost unparalleled richness of its lead silver gold ore created widespread interest in the property from which carlot after carlot of ore was shipped to salt lake city As shown in the cross section drawing herewith given the ore deposit is in blanket form the floor is devonian quartzite and the roof is lower carboniferous limestone and which is ip abundantly identified by fossil ry aknin i thin a few few paces of the workings pe the mine is situated low down in the ct eat t base of deer trail mountain or the so southeast theart portion of the bullion cottonwood di divide which reaches out easterly from the T ashar divide and abruptly descending to ilie ie marysvale Marys vale depression forms one of the J rugged and lofty escarpments in tah the rich ore was taken from those eints marked 2 and 3 on the longitudinal section drawing and where the high grade product product often of ten swelled to nearly three feet n thickness As those gunels traversed the contact on tact values decreased until all that re nains bains of the vein is about two feet of pure white granulated quartz in driving the annel marked 1 and other tunnels farther south in the contact it was found that the re thinned down to an inch or so in average lickness kness with a corresponding decrease of quartz after the rich ore had been exhausted at t points 2 and 3 a shaft was sunk on the hillside at the point marked A and which entered the ore body to the north of the shallow draw the level which was driven from the batom of the shaft opened up an ever thickening body of ore running 20 to 30 per ton in gold and silver subsequently at the point marked C a tunnel was driven in and the mammoth ore body afe frequently swelling to sixty feet in height was thoroughly explored but the value of the ore had largely decreased in lead gold and silver but the entire mass is ore and has an average value of not less than 5 gold and 10 ounces silver per ton at le least ast such is my recollection of the average of hundreds perhaps thousands of assays essays made by professor george T henry who has a carefully made record of each test much of the greater values are contained in thousands of tons of milk white tale talc composed of almost impalpable atoms from which until recently the contained atoms of gold and silver could not be cheaply extracted like that portion of the contact to the south of the greater ore body the values did not extend into the mountain the ore body rests on a wide terrace the floor and west side of which as shown in cross section is quartzite while on the east the ore merges into glacial cement and later debris from the mountain side it was observed by the first owners that seams of ore went downward into the quartzite and which induced them to sink a at the point marked D some eight years since the present owner had driven a tunnel in at the main point marked B see both engravings and an upraise made to the ore body all along the tunnel are vertical fractures and fissures in the quartzite occasionally those seams contain galena while the larger fractures are filled or stained with manganese As shown in the longitudinal drawing a huge porphyry dyke near north limit of the ore body cuts the country from below the mine to the top of the mountain but above the deer trail mine the almost horizontal strata of the lime affords no evidence of disturbance other than local fracturing or the usual effects of slight dynamic forces there is a slight fault a as s shown in the longitudinal section just to the right of tunnel 3 of ten to twelve feet oc vertical displacement and the ability of the quartzite as shown in the extreme right of cross section may ably be assigned a to faulting such are the conspicuous features of the deer trail formation and from which no doubt the student of ceolo geology y will anticipate the writers conclusions regarding the soure source e of the deer trail ore bodies in seeking for the origin of the ore bodies in the deer trail we must keep in iii mind two fundamental truths first that no na effect can exist in the absence of a cause or causes second that from dynamical geology to psychology force follows I 1 lines ines of least resistance another important truth that should be kept in view is that no cause or force can be accepted that does not account for all of the phenomena or effects involved in the problem to be solved and r T X N N e tion of D E RAIL 7 1 NINE aale lie 11 1 Z L I or ehg 4 an MEMO 41 fon S looking Loo kinq arol st speculative it is just as well to explain proceeding to discuss the speculative division of the subject that except for the important economic question involved in the can conclusions clu elu the task of preparing pre jaring this article would not have been undertaken speculative division very likely the first thought will be that the solution aacen ascended ded along t the porphyry dyke to the north and creeping along the contact to the south attacked the lime stone and replaced that substance with a filling composed of material largely derived from the limestone and including the metals from the porphyry dyke while that theory is certainly plausible and while tho the dyke was no doubt primarily the source of the larger portion of the values it does not account for the vertical an and d intricate fissuring of the quartzite the effect on the quartzite by a thrust movement from the intrusion of the dyke would have produced irregular shattering of the quartzite and any semi horizontal force or thrust sufficient to so profoundly fracture the quartzite would have sharply tilted the mass to the south instead the descent of 12 to to 15 degrees is towards the north the theory of direct derivation of the values from the fault is absolutely untenable in order to make the subject entirely clear to those who may not have unwisely taxed their brains and time in the unprofitable study of geology it will be well to begin at the beginning and by means of another illustration make the subject so plain that a child may understand it to the student of geology the accompany engraving tells the story of stupendous dynamical effects but which to the uninitiated may require some explanation the story begins with the close of the lower carboniferous boni ferous era when the mass of rocks in the CL ML V yay kat TYL 11 diw mercury Mev cury 1 5 aft A XA F GOS 0 aa e DeYess ln reck result oj FAULTING AIL MINE alse vicinity of marysvale Marys vale rose above the ocean and formed a great level plateau extending many miles in all directions at that time there was no porphyry dyke in the vicinity of the deer trail hence no ore it was probably quite early in the tertiary age when the break represented by the porphyry dyke in the longitudinal see sec tion took place as represented by the dotted lines lines the mountain extended to the eastward over the present site of the marys vale depression and at the present time the remaining section rises fully 2000 feet above the deer trail mine the resistance of the mountain mass to the upward movement of the embryo porphyry dyke was such that the lower contact as shown in two of the drawings became a line of least resistance or easement and a shaft of porphyry was forced out towards the south and very likely to the north the forcing out of such a sheet of porphyry would have produced just such a system of vertical trac frac turing as we find in the quartzite underneath the deer trail ore body that the upward movement of the quartzite was comparatively sudden is proved by the fractures and that the mass had no time to adjust itself as would have been the case had the lifting force been prolonged or had exerted itself uniformly under a larger area and it is a further significant fact that the quartzite js s less and less fractured in proportion to its distance from the dyke hot solutions or vapors ascending along the dyke found a line of easement between the sheet of porphyry and the limestone and the era of ore making had begun while making ore on the lower zone the heated solutions ascended through the fissures in the tha quartzite and made ore in the deer trail contact the rich ore first extracted was doubtless natures concentrates formed by a secondary flow of solutions which robbed the great ore deposit of part of its values and thus enriched the smaller ore body to the south after the ore bodies were thus formed at a depth of more than 2000 feet beneath the surface that profound break called the sevier fault occurred and a part of the mountain sank fully feet and now lies buried beneath glacial drift silt and in many places beneath beds and butted of lava and other volcanic along with the sunken mountain there unfortunately went the greater portion probably of the deer trail ore body eliminating the speculative portion of the foregoing discussion disc and the reader has the history of the deer trail mine perhaps no effort will ever be made to reach those speculative ore bodies but it Is indeed strange that not the slightest efort has been made to explore f e the country on the north side of the dyke where identical causes existed and where results similar to those on the south side almost certainly exist professor arthur lakes of colorado describes a similar occurrence in the to range from an enormous porphyry dyke a number of porphyry sheets were forced out between beds of quartzite and limestone and along the stratification lines of the latter and now form the bedded veins from which leadville draws its enormous mineral wealth in a way similar phenomena may be seen at mercur utah J F GIBBS