Porphyry and skarn type molybdenum-tungsten deposit.
It has a proven resource of 0.8 Mt Mo with an average grade of 0.133 %, and 0.36 Mt WO3 with an average grade of 0.066 %. The deposit is tectonically located between the Machaoying and Luanchuan faults. The orebodies at the Yechangping deposit include porphyry- and skarn-types. The porphyry-type orebodies occur in the porphyry stock with a radius of 100 m, whilst the skarn-type in an outer ring of 200–300 m wide. Hydrothermal alteration includes four zones, namely, porphyry (fine disseminated stockworks), endoskarn, exoskarn, and serpentinized humite marble. Four paragenetic stages are recognized in the Yechangping skarn orebody from early to late, namely the prograde skarn, retrograde skarn, polymetallic sulfides, and carbonate stages, corresponding to the magma cooling, barren quartz veins (with or without UST), quartz-molybdenite veins, and carbonate veins, respectively.

The mining area covers about 0.4 km2, with the porphyry and ore bodies completely concealed within the chert-bearing dolomitic marble of the Longjiayuan Formation of Guandaokou Group. From shallow to deep, three stratiform-like skarn-type orebodies (I, II-1, and III-1) and two lens-shaped porphyry-type orebodies (II-2 and III-2) can be recognized. The overall length of the orebody varies between 450 and 900 m, with a width of 600 m, and a thickness spanning from 170–320 m. Skarn-type orebodies generally exhibit higher grades, ranging from 0.124 % to 0.151 % Mo, while porphyry-type ore bodies have average grades ranging from 0.084 % to 0.092 % Mo.

The Yechangping deposit, as a giant porphyry-skarn Mo-W deposit (0.81 Mt @ 0.128 % Mo, 0.42 Mt @ 0.066 % WO3). Specifically, Mo-W mineralization mainly occurs in rare magnesium skarns that are genetically related to granite porphyry. The main lithostratigraphic units in the deposit area are the Mesoproterozoic Longjiayuan and Xunjiansi Formations, with minor Quaternary sediments. The Longjiayuan Formation consists mainly of siliceous banded dolomite with minor stromatolite and lower biotite hornfels, while the Xunjiansi Formation is composed of argillaceous dolomite and siliceous banded dolomite, overlain by the Longjiayuan Formation.
The Yechangping deposit exhibits two principal types of alteration and mineralization systems with distinct spatial zonation: porphyry-type and magnesium skarn-type assemblages. The porphyry-style hydrothermal system occurs predominantly in granitic porphyries with three successive alteration phases: (1) potassic alteration, (2) propylitic alteration, and (3) phyllic alteration.

Skarn-type mineralization can be further subdivided into five successive stages: (I) early skarn, (II) late skarn, (III) oxide, (IV) quartz–sulfide, and (V) carbonate–sulfide.

Other Regions, Features and Areas containing this locality

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