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Petrology and geochemistry of adakitic intrusions and dykes at Sarcheshmeh porphyry Cu-Mo ± Au deposit, Iran: Insights into their source
Resource Geology ( IF 1.4 ) Pub Date : 2022-08-10 , DOI: 10.1111/rge.12297
Mohammad Maanijou 1 , Mohammad Mostaghimi 1 , Mehdi Abdollahy Riseh 2 , David R. Lentz 3 , Ali A. Sepahi Gerow 1
Affiliation  

The Sarcheshmeh porphyry copper deposit (PCD) is located in the southeast part of the arc-related Urumieh-Dokhtar volcano-plutonic belt. This PCD was formed by intrusion of a Middle Miocene granodiorite to tonalite stock into the volcano-sedimentary rocks that are mainly andesite exhibiting Early Tertiary thrusting and faulting. On the basis of geochemistry of intrusive rocks, they are calc-alkalic and alkali-calcic suites that are consistent with oxidized I-type magmas. The Fe2O3/FeO ratio in the Sarcheshmeh PCD is 1 to 3, consistent with a high oxygen fugacity. The igneous rocks of Sarcheshmeh PCD belong to a mature arc, but related to a post-collision arc setting. Considerable evidence supports adakitic affinities of the Sarcheshmeh rocks, including geochemical values of Sr > 300 ppm (ave., 594 ppm), high ratios of Sr/Y > 20 (ave., 75), La/Yb > 20 (ave., 30), and enrichment of LREE and LILE relative to HREE and HFSE. The adakites of Sarcheshmeh belong to high-silica adakites (HSA) that can be formed by melting of subducting seawater-altered oceanic plate, which interact with the mantle wedge then followed by slab break-off with local transtension in the middle part of the Dehaj-Sarduieh belt. In rocks of the region, the ratios of Th/Ce > 0.12 and Nb/Zr > 0.05 suggest that the subducting crust has a role in forming different groups of these rocks. Geotectonic discrimination diagrams are used to distinguish between normal arc and slab failure magmatic systems, including Nb versus Y, La/Sm versus Sm/Yb, La/Yb versus Gd/Yb, and Rb versus Nb + Y diagrams. The plutonic rocks of the Sarcheshmeh PCD have characteristics consistent with adakites derived via slab failure, which are obviously metallogenically favorable magmatic systems. Adakitic melts generated rapidly during sinking of a broken slab (into higher temperature mantle), buoyantly migrate through the subcontinental lithospheric mantle (SCLM), which is related to structural evolution of that SCLM with local extension or transpression.

中文翻译:

伊朗 Sarcheshmeh 斑岩 Cu-Mo ± Au 矿床埃达克质侵入体和岩脉的岩石学和地球化学:对其来源的见解

Sarcheshmeh斑岩铜矿床(PCD)位于与弧有关的Urumieh-Dokhtar火山-深成带的东南部。该PCD是由中中新世花岗闪长岩侵入到火山沉积岩中形成的,主要是安山岩,表现出早第三纪逆冲和断层。侵入岩地球化学特征为钙-碱型和碱-钙型岩浆,与氧化I型岩浆相一致。Fe 2 O 3Sarcheshmeh PCD 中的 /FeO 比率为 1 比 3,与高氧逸度一致。Sarcheshmeh PCD 的火成岩属于成熟弧,但与碰撞后弧背景有关。大量证据支持 Sarcheshmeh 岩石的埃达克质亲和力,包括 Sr > 300 ppm(平均,594 ppm)的地球化学值,Sr/Y > 20(平均,75)的高比率,La/Yb > 20(平均, 30),以及相对于 HREE 和 HFSE 的 LREE 和 LILE 的富集。Sarcheshmeh的埃达克岩属于高硅埃达克岩(HSA),可以通过俯冲海水改变的海洋板块与地幔楔相互作用形成高硅埃达克岩(HSA),然后在Dehaj中部发生板片断裂和局部伸展-Sarduieh 腰带。该区岩石中,Th/Ce>0.12,Nb/Zr>0。05表明俯冲地壳在形成这些岩石的不同组中起作用。大地构造判别图用于区分正弧和板片破坏岩浆系统,包括 Nb 与 Y、La/Sm 与 Sm/Yb、La/Yb 与 Gd/Yb 以及 Rb 与 Nb + Y 图。Sarcheshmeh PCD 的深成岩具有与板片破坏形成的埃达克岩一致的特征,显然是有利成矿的岩浆系统。在破碎板片下沉(进入高温地幔)过程中迅速产生的埃达克质熔体通过次大陆岩石圈地幔(SCLM)快速迁移,这与该SCLM的结构演化有关,具有局部伸展或挤压作用。大地构造判别图用于区分正弧和板片破坏岩浆系统,包括 Nb 与 Y、La/Sm 与 Sm/Yb、La/Yb 与 Gd/Yb 以及 Rb 与 Nb + Y 图。Sarcheshmeh PCD 的深成岩具有与板片破坏形成的埃达克岩一致的特征,显然是有利成矿的岩浆系统。在破碎板片下沉(进入高温地幔)过程中迅速产生的埃达克质熔体通过次大陆岩石圈地幔(SCLM)快速迁移,这与该SCLM的结构演化有关,具有局部伸展或挤压作用。大地构造判别图用于区分正弧和板片破坏岩浆系统,包括 Nb 与 Y、La/Sm 与 Sm/Yb、La/Yb 与 Gd/Yb 以及 Rb 与 Nb + Y 图。Sarcheshmeh PCD 的深成岩具有与板片破坏形成的埃达克岩一致的特征,显然是有利成矿的岩浆系统。在破碎板片下沉(进入高温地幔)过程中迅速产生的埃达克质熔体通过次大陆岩石圈地幔(SCLM)快速迁移,这与该SCLM的结构演化有关,具有局部伸展或挤压作用。Sarcheshmeh PCD 的深成岩具有与板片破坏形成的埃达克岩一致的特征,显然是有利成矿的岩浆系统。在破碎板片下沉(进入高温地幔)过程中迅速产生的埃达克质熔体通过次大陆岩石圈地幔(SCLM)快速迁移,这与该SCLM的结构演化有关,具有局部伸展或挤压作用。Sarcheshmeh PCD 的深成岩具有与板片破坏形成的埃达克岩一致的特征,显然是有利成矿的岩浆系统。在破碎板片下沉(进入高温地幔)过程中迅速产生的埃达克质熔体通过次大陆岩石圈地幔(SCLM)快速迁移,这与该SCLM的结构演化有关,具有局部伸展或挤压作用。
更新日期:2022-08-11
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