Abstract
老厂矿床是昌宁-孟连缝合带内唯一大型矿床，本文报道了老厂矿床Ag-Pb-Zn矿体中Ⅰ号矿体群下部块状矿体和上部网脉状矿体的方解石C-O同位素组成，以及Ⅰ、Ⅱ、Ⅳ三个矿体群内闪锌矿的Zn同位素组成。Ⅰ号矿体群下部块状矿体和上部网脉状矿体方解石δ<sup>13</sup>C<sub>PDB</sub>的范围分别为-6.17‰~2.71‰和-2.18‰~3.87‰，δ<sup>18</sup>O<sub>PDB</sub>的范围分别为-19.57‰~-17.23‰和-22.10‰~-16.21‰；计算获得对应成矿流体的δ<sup>13</sup>C<sub>CO<sub>2</sub></sub>为-6.16‰~1.53‰和-2.39‰~6.43‰，δ<sup>18</sup>O<sub>H<sub>2</sub>O</sub>分别为1.62‰~7.62‰和4.36‰~16.92‰，通过与岩浆CO<sub>2</sub>（δ<sup>13</sup>C=-2‰~-8‰）和围岩灰岩（δ<sup>13</sup>C=-1.6‰~4.0‰）的δ<sup>13</sup>C值相比较，指示块状矿体成矿流体中的碳主要来自岩浆，网脉状矿体成矿流体中的碳则主要来自围岩，说明老厂矿床深部水岩反应较强。10件闪锌矿的δ<sup>66</sup>Zn和δ<sup>68</sup>Zn值分别为0.17‰~0.25‰和0.33‰~0.49‰，与VMS型矿床以及现代海底热液流体的Zn同位素组成重合，不同标高均一的Zn同位素组成寓示老厂矿床Ag-Pb-Zn矿体中闪锌矿形成过程中几乎未受到温度、分馏和微生物作用的影响，可以直接反映金属源区的Zn同位素组成，揭示老厂矿床Ag-Pb-Zn矿体为VMS成因，成矿金属主要来自于下石炭统海底火山作用。;The Laochang deposit is the only large ore deposit in the Changning-Menglian suture zone. In this study, the C-O isotopic compositions of calcites from the lower massive ore bodies and the upper stockwork ore bodies of No.Ⅰ ore bodies in Laochang Ag-Pb-Zn ore bodies and the Zn isotopic compositions of sphalerites from No.Ⅰ, Ⅱ, Ⅳ ore bodies are investigated. The range of δ<sup>13</sup>C<sub>PDB</sub> of calcites from the lower massive ore bodies and the upper stockwork ore bodies of No.Ⅰ ore bodies is -6.17‰~2.71‰ and -2.18‰~3.87‰, respectively, and the range of δ<sup>18</sup>O<sub>PDB</sub> is -19.57‰~-17.23‰ and -22.10‰~-16.21‰, respectively. The δ<sup>13</sup>C<sub>CO<sub>2</sub></sub> of the corresponding ore-forming fluids are calculated to be -6.16‰~1.53‰ and -2.39‰~6.43‰, respectively, and the δ<sup>18</sup>O<sub>H<sub>2</sub>O</sub> are calculated to be 1.62‰~7.62‰ and 4.36‰~16.92‰, respectively. By comparison with the δ<sup>13</sup>C of magmatic CO<sub>2</sub> (δ<sup>13</sup>C=-2‰~-8‰) and wall-rock limestone (δ<sup>13</sup>C=-1.6‰~4.0‰), it indicates that the carbon in the ore-forming fluids of massive ore bodies mainly comes from magma, while the carbon in the ore-forming fluids of stockwork ore bodies mainly comes from limestone, which further shows that there is strong water-rock reaction in the deep part of Laochang deposit. The δ<sup>66</sup>Zn and δ<sup>68</sup>Zn values of ten sphalerites are 0.17‰~0.25‰ and 0.33‰~0.49‰, respectively, which coincides with the Zn isotopic compositions of VMS deposits and modern submarine hydrothermal fluids. The homogeneous Zn isotopic compositions at different elevations implies that the Zn isotopic compositions of sphalerite from Ag-Pb-Zn orebodies in Laochang deposit are almost unaffected by temperature, fractionation and microbial action. And it can directly reflect the Zn isotopic compositions of the metal source, revealing the genesis type of the Laochang Ag-Pb-Zn ore body as VMS-type, and the metallogenic metal mainly comes from the Lower Carboniferous submarine volcanism.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
