این کتاب در فیلد «زمینشناسی، اکتشاف و معدنکاری مس» و زیرموضوع «اکتشاف و کانیسازی مس» قرار میگیرد. محورهای قابل تشخیص از عنوان و متادیتای Lens عبارتاند از: ژئوشیمی، هزینه و اقتصاد. این منبع یک منبع پشتیبان تخصصی است که روشها و مبانی آن در صنعت مس کاربرد دارد. برای شناخت کانسار، هدفگذاری اکتشافی، طراحی معدن و بررسی عملیات استخراج کاربرد دارد. این متن یک خلاصه موضوعی فارسی بر پایه متادیتای موجود است؛ چکیده انگلیسی، در صورت وجود، در ستون جداگانه حفظ شده است.
چکیده انگلیسی
The Nizina district lies on the southeast flank of the Wrangell Mountains, about 60 miles east of Chitina and about 200 miles by automobile road and rail from the port of Valdez. The first copper claims were located in 1899. From 1911 to 1938 the district produced more than a billion pounds of copper, nearly all from the Kennecott mines. When the Kennecott mines closed and the railroad to Cordova was abandoned, in 1938, copper production ceased, except for a few tons of copper nuggets recovered as a byproduct of gold-placer operations. The host rocks of the copper deposits are the Nikolai greenstone, consisting of altered basaltic lava flows of Permian and Triassic (?) age, and the overlying Chitistone limestone, consisting of massive thick-bedded limestone of Upper Triassic age. The greenstone and limestone are folded into a broad syneline trending northwest. The deposition of the ore bodies was controlled in part by minor cross folds, steeply dipping faults that strike at a large angle to the. axis of the major fold, and bedding faults. Chalcocite is the principal copper mineral in most of the deposits in limestone, and bornite and chalcocite are the principal copper minerals in the deposits in greenstone. Native copper also occurs in the greenstone. Nearly all the ore has come from the lowest 300 feet of the Chitistone limestone. In this report 7 mines and about 13 prospects, comprising nearly all of the known copper deposits of the district, are described briefly. None of theknown deposits is believed to offer sufficient promise of significant production or profit to warrant the cost of reestablishing a practicable means of transportation to the district solely for the copper.
