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The Beiligaimiao magmatic Ni-Cu sulfide deposit is located in the northern rim of the North China Block, which was an active continental margin related to the southward subduction of the Paleo-Asian oceanic plate to the north in the Paleozoic. This deposit has never been studied before but is an excellent example of sulfide mineralization in arc settings that have been commonly overlooked by exploration geologists worldwide. Sulfide mineralization in the deposit is hosted in a mafic-ultramafic complex that consists of a small ultramafic body surrounded by an older and much larger gabbroic intrusion. Disseminated sulfide zones are present in both intrusive bodies but only those close to the surface within the ultramafic body have been mined in the past. The sulfide-mineralized ultramafic body is composed of olivine websterite and orthopyroxenite with a gradational contact between them. SIMS U-Pb dating of zircon crystals from a large olivine websterite sample yields a crystallization age of 269.4 ± 2.1 Ma, which is ∼25 Ma younger than the Erbutu subduction-related magmatic Ni-Cu sulfide deposit that occurs ∼50 km to the north. Orthopyroxene crystals in the Beiligaimiao ultramafic rocks have Mg # [100 Mg/(Mg + Fe), molar] of 77–78, significantly lower than those in the ultramafic rocks of the Erbutu deposit. Olivine crystals in the Beiligaimiao ultramafic rocks have forsterite (Fo) contents from 72 to 75 mol%, which are also significantly lower than those in the ultramafic rocks of the Erbutu deposit (Fo, 86–88 mol%). The mineral chemical data indicate a more fractionated parental magma for the former. Ca-depletion in olivine (i.e., <1000 ppm Ca), which is common for ultramafic cumulates in arc settings worldwide, is present in both deposits. Like Erbutu, the host rocks of the Beiligaimiao deposit are characterized by enrichments in light rare earth elements (REE) relative to heavy REE and pronounced negative Nb-Ta anomalies, consistent with ultramafic rocks in arc settings. The δ 34 S values of sulfide separates from the Beiligaimiao deposit are 1.7 to 2.5‰, significantly lower than those for the Erbutu deposit but still slightly higher than the MORB value (−1.5 to 0.5‰). Olivine websterites in the Beiligaimiao deposit have ε Nd from −8.9 to −9.5 and ( 87 Sr/ 86 Sr) i close to 0.7075, which are similar to those of an enriched lithospheric mantle. An orthopyroxenite sample from the deposit has much lower ε Nd (−12.6) coupled with much higher ( 87 Sr/ 86 Sr) i ratio (0.7132), indicating ∼25% crustal contamination. The Sr-Nd-S isotope data support the premise that both crustal contamination and addition of crustal sulfur played a role in triggering sulfur saturation in the parental magma of the Beiligaimiao deposit. Since the immediate country rocks are exclusively gabbros, these processes likely took place at depth. The close temporal and spatial association of the Beiligaimiao and Erbutu deposits points to the possibility that more Permian arc-type magmatic sulfide deposits are yet to be discovered in the region. [ABSTRACT FROM AUTHOR]

The article presents a study on uranium?lead (U-Pb) dating and laser ablation?inductively coupled plasma?mass spectrometry (LA-ICP-MS) of Middle Permian granite of Langshan Mountain, China and its indicating significance. Topics discussed include characteristics of granite such as finegrained texture and massive structure; chemical composition of granite and selection of zircon to carry on LA-ICP-MS U-Pb dating.

The Badaguan porphyry Cu Mo deposit is located in the Derbugan metallogenic belt of northeastern Inner Mongolia, China. The host granodioritic porphyry and the wall rock granitic porphyry were emplaced at 230 Ma and 238 Ma, respectively. The granodioritic porphyry has ( 87 Sr/ 86 Sr) i values of 0.70535–0.70549, ε Nd (t) values of 0.41–1.17, ε Hf (t) values of 1.30–6.51, and two–stage model ages (T DM2 ) of 1131–848 Ma. In contrast, the granitic porphyry is characterized by ε Hf (t) values from − 0.75 to 7.28 that yield T DM2 model ages of 1355–816 Ma. The geochemical and Sr Nd Hf isotopic data for the magmatic rocks associated with the Badaguan porphyry Cu Mo deposit indicate that these intrusions were generated by the partial melting of juvenile lower crust. The δ 18 O values of ore fluids from different mineralizing stages are between − 6.0‰ and + 1.5‰, and the fluid δD water values vary from − 119.3‰ to − 140.0‰, indicating a mixed fluid of magmatic and meteoric water, the S Pb isotopes show that the metal was mostly derived from a deep-seated magma that involved some crustal materials, with a narrow δ 34 S range (− 2.4‰ to + 3.5‰). We infer that the Badaguan porphyry Cu Mo deposit formed during a period of southeast–directed subduction of the Mongol–Okhotsk oceanic plate beneath the Erguna Block. [ABSTRACT FROM AUTHOR]