Cambrian (~510 Ma) ophiolites of the East Kunlun orogen, China: A case study from the Acite ophiolitic tectonic mélange Ruibao Li XianZhi Pei Zuochen Li Lei Pei Guochao Chen Bo Wei Youxin Chen Chengjun Liu Meng Wang 10.6084/m9.figshare.5633734.v1 https://tandf.figshare.com/articles/dataset/Cambrian_510_Ma_ophiolites_of_the_East_Kunlun_orogen_China_A_case_study_from_the_Acite_ophiolitic_tectonic_m_lange/5633734 <p>The Acite ophiolitic mélange represents a remnant of the Proto-Tethys forearc oceanic lithosphere. Two gabbros yield zircon <sup>206</sup>Pb/<sup>238</sup>U ages of 510-512 Ma. The magmatic rocks are divided into three subtypes: (1) Mid-ocean ridge basalt (MORB) -like forearc basalts (FABs), (2) Low-titanium tholeiitic gabbros (LTGs), and (3) Normal calc-alkaline dacites (CADs). The FABs have comparatively higher TiO<sub>2</sub> concentrations (1.13–1.42 wt%) and show almost flat REE patterns. In the NMORB normalized trace element patterns, the FABs display flat distributions of high field strength element (HFSE). The <i>ε</i><sub>Nd</sub>(t) values of FABs range from +4.0 to +4.8. These features are similar to the composition of Izu-Bonin-Mariana forearc basalts (FABs). LTGs are characterized by higher contents of MgO (8.85–9.95 wt%) and lower concentration of TiO<sub>2</sub>(0.29–0.50 wt%). They show LREE-depleted patterns, however having comparatively lower total REE contents than those of FABs. The <i>ε</i><sub>Nd</sub>(t) values of LTGs range from +7.4 to +8.4. These features show that LTG magmas originated from a progressively depleted mantle source. In contrast, the CADs having higher SiO<sub>2</sub> contents (63.58–70.92 wt%) have higher total REE contents. In the NMORB normalized trace element patterns, CADs are characterized by enrichment of LILEs and depletion of HFSEs. CADs have negative <i>ε</i><sub>Nd</sub>(t) values ranging from -9.8 to -10.5, which are likely suggestive of a crust-derived source. The rock association of FABs and LTGs, together with tectonic discrimination plots and regional data, suggest a forearc setting above the SSZ for Acite ophiolitic mélange.</p> 2017-11-27 07:10:40 Supra-subduction zone (SSZ) forearc ophiolite East Kunlun Tibet Plateau Tethys boninite