Spatio-and temporal patterns of Jurassic–Early Cretaceous volcanism in the Great Xing’an range, NE China: constraints on the geodynamic evolution

Tracing coupled ocean closure and intra-continental orogenic processes using tectonomagmatic thermal events is important for performing plate reconstructions. In this study, we collected geochronological data obtained from Jurassic–Early Cretaceous volcanic sequences in the Great Xing apos; an Range (GXR) and compared and merged the data to obtain a better understanding of the timing of volcanism in the GXR. Jurassic–Early Cretaceous volcanism, which is mainly represented by the Tamulangou, Manketouebo, and Manitu formations, are ubiquitous in the GXR and do not contain a magmatic hiatus. Thus, ‘diachronous’ volcanism did not occur in the GXR. The volcanic sequences in these formations are also slightly ambiguous and therefore cannot be used to determine the timing of volcanism. However, absolute ages and rock assemblages can provide better constraints on this timing. Combined with data from Jurassic–Early Cretaceous tectonomagmatic thermal events in Mongolia, Siberia, and NE China, we re-evaluated the influences of the Jurassic–Early Cretaceous closure of the Mongol–Okhotsk Ocean (MOO), as well as the subduction and rollback of the Izanagi Plate, at different times in the GXR. The GXR likely underwent flat-slab subduction during the Late Jurassic–early Cretaceous as the MOO closed in an irregular ‘scissor-like’ fashion (i.e. not in a progressive west to east manner). Large-scale lithospheric delamination likely led to a large pulse of magmatism and mineralisation in the GXR during the late Early Cretaceous.利用构造岩浆热事件示踪耦合的洋盆闭合与陆内造山过程，对于开展板块重建研究具有重要意义。本研究收集了大兴安岭（Great Xing'an Range, GXR）侏罗纪-早白垩世火山岩序列的年代学数据，并对数据进行对比与整合，以更深入地理解大兴安岭的火山活动时限。以塔木兰沟组、满克头鄂博组、玛尼吐组为代表的侏罗纪-早白垩世火山作用在大兴安岭广泛分布，且未出现岩浆间断，因此该区域不存在穿时火山作用。上述各组的火山岩序列尚存一定模糊性，无法直接用于限定火山活动时限，但绝对年龄与岩石组合可对此提供更可靠的约束。结合蒙古、西伯利亚及中国东北的侏罗纪-早白垩世构造岩浆热事件数据，我们重新评估了蒙古-鄂霍次克洋（Mongol–Okhotsk Ocean, MOO）侏罗纪-早白垩世闭合过程，以及伊泽奈崎板块（Izanagi Plate）的俯冲与后撤作用在不同时期对大兴安岭的影响。随着蒙古-鄂霍次克洋以不规则‘剪刀式’（而非渐进式西-东向）方式闭合，大兴安岭在晚侏罗世-早白垩世早期可能经历了平板俯冲作用。早白垩世晚期，大规模岩石圈拆沉作用可能引发了大兴安岭地区强烈的岩浆活动与成矿作用。