Stages and Formation Conditions of Productive Mineral Associations of the Dalnegorsk Borosilicate Deposit, Sikhote Alin

Skarn-Borosilicate Giant Deposits: Derivates of the Fluid-Hydrothermal Reworking of Atoll Fragments in a Subduction Melange of Mesozoic Orogenic Belts of Asia

“…Скарнирование в объеме месторождения проявилось дважды [26]. На раннем этапе в теле известняков была образована гигантская колонна гроссуляр-волластонитовых скарнов, практически нацело заместивших известняки в интервале современных глубин от 0.5 до 1.2 км.…”

Nature of the Skarn–Borosilicate Deposit Giants of the Sikhote-Alin and Pamir Mountains

“…1). Skarns in the volume of the deposit appeared twice [5]. At an early stage, a column of grossular-wollastonite skarns was formed in the limestone body, almost completely replacing limestones in the range of modern depths from 0.5 to 1.2 km.…”

“…Danburite was transformed into a coarse-crystalline quartz-calcite aggregate. At the same time, the boron that was mobilized during the hydrothermal processing of early ores was fixed in the same zone in the form of datolite and axinite in association with late skarns [5,9]. The primary danburite ores avoided replacement and redeposition only in the northeastern part of the Dalnegorskoe deposit (Fig.…”

“…Thermobarogeochemical study showed that danburite was formed in the temperature range 350-200°С with the participation of solutions enriched with CO 2 and saturated with sodium and magnesium chlorides, with an increase in their salinity from 2.9 to 16.34 wt % eq. NaCl under decreasing temperatures [5]. According to [10], mineral associations with danburite were formed with the participation of fluids with anomalous boron and lithium contents in the range of 6.20-53.80 and 0.104 g/kg of solution, respectively.…”

“…According to our data [11], danburite boron, at δ 11 В = +17.7‰, corresponds to evaporites of marine origin. According to study of the oxygen isotopic composition [5], the formation of danburite occurred from the intensely diluted meteoric component of solutions of magmatic origin, with fluid δ 18 О values of about -1.0‰.…”