Review of the regional nomenclature and tectonic setting for mesozoic gold deposits in the Malanyu Anticline area of Eastern Hebei Province, North China

North China (NC) is a region recording a long and complex geological history spanning from the Archaean to Cenozoic. This included magmatism, sedimentation, metamorphism, and deformation, demonstrating that the region is not a craton. To date, few studies have considered the links between multiple deformation events, emplacement of granites, and the deposition of gold deposits during the Mesozoic evolution of northeastern NC coeval with deformation in the Central China Orogen. The Malanyu area is a well-exposed part of NC, where almost continuous sedimentation and multiple deformation events are recorded. Long-lived magmatism broadly extended between ca. 220 and 118 Ma and is concentrated in the hinge zone of the east-trending Malanyu Anticline, which is a large-scale anticline deformed multiple times. Timing relationships between sedimentation, deformation, and magmatism show that the structure must be between 250 and 220 Ma. The upper limit corresponds to the closure of the Palaeoasian Ocean during the onset of collision between the Central Asian Orogen and NC to the south. Magmatism in the anticline’s hinge zone can be subdivided into three magmatic events between ca. 220–214, 200–143 and 128–118 Ma separated at ca. 212–202 Ma and ca. 140–130 Ma, and these periods of magmatic hiatus correspond to unconformities in the sedimentary succession. The oldest granite in the area is ca. 220 Ma limiting the age of the anticline between ca. 250 and 220 Ma. The gold mineralisation was emplaced in structurally prepared sites along faults and anticline hinge zones and broadly contemporaneous with the magmatic events. The gold assays of samples collected for this study show that the hinge zone of the Malanyu Anticline, around the intersection of the Myun-Xifengkou-Qinglong Shear Zone and Baiyangyu Fault, the area west of the Dashan Granite, and the northwestern part of the study area are prospective for gold.

华北（North China, NC）是一段记录了从太古宙至新生代漫长且复杂地质演化历史的区域，其演化过程涵盖岩浆作用、沉积作用、变质作用与构造变形，表明该区域并非克拉通（craton）。迄今为止，鲜有研究关注华北东北部中生代演化过程中多期构造变形事件、花岗岩侵位与金矿床形成之间的关联，而该演化时期恰好与中央造山带的变形作用同期。马兰峪地区是华北区域出露良好的构造单元之一，区内记录了近乎连续的沉积序列与多期构造变形事件。持续时限较长的岩浆作用大致分布于约220 Ma至118 Ma之间，且集中发育于近东西向马兰峪背斜的枢纽带——该背斜为经历过多期变形的大型褶皱构造。沉积作用、构造变形与岩浆作用的时序关系表明，该背斜的形成时代介于250 Ma至220 Ma之间，其上限对应于中亚造山带与南侧华北地块碰撞启动时，古亚洲洋（Palaeoasian Ocean）的闭合过程。马兰峪背斜枢纽带的岩浆作用可细分为三期：分别为约220~214 Ma、200~143 Ma与128~118 Ma，其间的212~202 Ma与140~130 Ma为岩浆间歇期，这些间歇期对应沉积序列中的不整合面（unconformities）。该区域最古老的花岗岩形成时代约为220 Ma，进一步将马兰峪背斜的形成时代限定于约250 Ma至220 Ma之间。金矿化作用赋存于沿断层与背斜枢纽带形成的构造有利部位中，且大致与各期岩浆作用同期。本研究采集样品的金含量化验结果显示，马兰峪背斜枢纽带、桲杖子-西峰口-青龙剪切带（Myun-Xifengkou-Qinglong Shear Zone）与白羊峪断层（Baiyangyu Fault）交汇区周边、大山花岗岩体（Dashan Granite）西侧以及研究区西北部均具有良好的金矿找矿潜力。