Details

Autor(en) / Beteiligte

• Deng, Yu-Feng
• Song, Xie-Yan
• Hollings, Pete
• Chen, Lie-Meng
• Zhou, Taofa
• Yuan, Feng
• Xie, Wei
• Zhang, Dayu
• Zhao, Bingbing

Titel

Lithological and geochemical constraints on the magma conduit systems of the Huangshan Ni-Cu sulfide deposit, NW China

Ist Teil von

• Mineralium deposita, 2017-08, Vol.52 (6), p.845-862

Ort / Verlag

Berlin/Heidelberg: Springer Berlin Heidelberg

Erscheinungsjahr

2017

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Magmatic Ni-Cu sulfide deposits in northern Xinjiang, China, are associated with small mafic-ultramafic complexes, with the sulfide ores generally occurring in ultramafic rocks. The Huangshan deposit (up to 65 Mt of ore at 0.49% Ni and 0.31% Cu), one of the largest magmatic Ni-Cu deposits in northern Xinjiang, is composed of a layered sequence of lower websterite, lower lherzolite, websterite, norite-gabbro, gabbro, diorite, and gabbronorite, with sulfide mineralization mainly found in the lower lherzolite, lower websterite, and websterite. Systematic variations of the major oxides and trace elements suggest that the rocks of the Huangshan deposit are fractionated from the same parental magma, with the sharp contact and discontinuous trends of major oxide contents between different lithologies implying intrusion of four distinct stages of magma from a single deep-seated staging chamber. The reversals in olivine Fo contents and major oxides in the lower lherzolite were the result of inhomogeneity in olivine within the lower chamber. The Se/S ratios (63.1∼150 × 10 −6 ) and the negative correlation between Se/S and δ 34 S (0.63∼2.42‰) of the sulfide ores suggest that a large contribution of crustal S caused the sulfide segregation. The sulfides in the lower lherzolite have lower Cu contents (1386–2200 ppm) and Cu/Pd ratios (2.31 × 10 5 –1.36 × 10 6 ) relative to those in the mineralized lower websterite (Cu = 2300 to 18,700 ppm, and Cu/Pd = 6.65 × 10 5 to 2.73 × 10 6 ). A positive correlation between Pd/Ir and Ni/Ir for the vein-textured sulfides in the lower websterite likely reflects fractionated sulfides picked up by a new pulse of magma. In contrast, the restricted range of Pd/Ir ratios indicates that the PGE contents of the disseminated sulfides in the lower lherzolite resulted from reaction between the sulfides and new pulses of S-undersaturated magma.