  Citation: Liu, J.; Wang, J.; Hattori, K.; Wang, Z. Petrogenesis of Garnet Clinopyroxenite and Associated Dunite in Hujialin, Sulu Orogenic Belt, Eastern China. Minerals 2022, 12, 162. https://doi.org/10.3390/ min12020162 Academic Editors: Hafiz U. Rehman, Atsushi Kamei, Clemente Recio and Yaoling Niu Received: 16 December 2021 Accepted: 25 January 2022 Published: 28 January 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). minerals Article Petrogenesis of Garnet Clinopyroxenite and Associated Dunite in Hujialin, Sulu Orogenic Belt, Eastern China Jianguo Liu 1 , Jian Wang 2, * , Keiko Hattori 3 and Zeli Wang 4 1 School of Resources and Environmental Engineering, Shandong University of Technology, Zibo 255000, China; liujg@sdut.edu.cn 2 College of Earth Sciences, Jilin University, Changchun 130061, China 3 Department of Earth and Environmental Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; khattori@uottawa.ca 4 College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China; wangze_li@126.com * Correspondence: wangjian304@jlu.edu.cn Abstract: The origin of ultramafic rocks, especially those in suture zones, has been a focus because they are not only important mantle sources of magma, but also provide substantial information on metamorphism and melt/fluid–peridotite interaction. Ultramafic rocks in Hujialin, in the central part of the Sulu orogen, include peridotite and pyroxenite. Although many papers on their origin and tectonic evolution have been published in the past few decades, these questions are still highly debated. Here, we present mineralogy, mineral composition, and bulk-rocks of these ultramafic rocks to evaluate their origin and tectonic evolution. The garnet clinopyroxenite is low in heavy rare-earth elements (HREE, 5.97–10.6 ppm) and has convex spoon-shaped chondrite-normalized REE patterns, suggesting the garnet formed later, and its precursor is clinopyroxenite. It is high in incompatible elements (i.e., Cs, Rb, Ba) and shows negative to positive U, Nb, and Ta anomalies, without pronounced positive Sr or Eu anomalies. Clinopyroxene in garnet clinopyroxenite contains high MgO (Mg # 0.90–0.97). The mineral chemistry and bulk-rock compositions are similar to those of reactive clinopyroxenite, suggesting that it originally formed via peridotite–melt interaction, and that such silicic and calcic melt might derive from the subducted Yangtze continent (YZC). Dunite contains olivine with high Fo (93.0–94.1), low NiO (0.11–0.29 wt.%) and MnO (≤0.1 wt.%), chromite with high Cr # (0.75–0.96), TiO 2 (up to 0.88 wt.%), and Na 2 O (0.01–0.10 wt.%). It has negatively sloped chondrite-normalized REE patterns. Mineral chemistry and bulk rocks suggest dunite likely represent residual ancient lithosperic mantle peridotite beneath the North China Craton (NCC) that was overprinted by aqueous fluids. The lack of prograde and retrograde metamorphic minerals in dunite and irregular shaped mineral inclusions in chromite suggest dunite did not subduct to deep levels. Dunite mingled with garnet clinopyroxenite during exhumation of the latter at shallow depths. These ultramafic rocks, especially hydrated peridotite, may be important sources of Au for the Jiaodong gold province in the NCC. Keywords: Sulu orogenic belt; clinopyroxenite; North China Craton; melt–peridotite interaction 1. Introduction The Dabie-Sulu orogenic belt formed from the subduction of Yangtze Craton (YZC) beneath the North China Craton (NCC) in the Triassic in east-central China [1–3]. It is one of the largest ultrahigh-pressure (UHP) metamorphic terranes in the world with an exposed area of about 30,000 km 2 [4,5]. The terrane is mainly composed of granitic gneisses, with volumetrically minor ultramafic rocks occurring as massifs and lenticular bodies. These ultramafic rocks include garnet peridotite, spinel peridotite, and pyroxenite. They mainly distribute in Weihai, Rongcheng (Chijiadian, Lijiatun, and Macaokuang), Jiangzhuang, Xugou, Rizhao (Suoluoshu and Hujialin), and Yangkou [1,2,6] (Figure 1a). Minerals 2022, 12, 162. https://doi.org/10.3390/min12020162 https://www.mdpi.com/journal/minerals