Abstract Subduction initiation and arc–polarity reversal have rarely been recognized in the Archean rock record. We document Neoarchean subduction initiation, fore-arc magmatism, and an arc–polarity reversal event from the Zunhua ophiolitic melange along the eastern margin of the Central Orogenic Belt (COB) of the North China Craton (NCC). The Zunhua ophiolitic melange is a mappable unit characterized by blocks of metamorphosed harzburgite/lherzolite, podiform chromite–bearing dunite, pyroxenite, amphibolite, metabasites (basalt and diabase) with rare intermediate volcanics, chert, and tectonic lenses of banded iron formation in a strongly sheared metapelitic matrix. New geochronological and geochemical analyses of magmatic blocks within the ophiolitic melange show that the crustal magmatic rocks were produced in a fore-arc region at 2.55–2.52 Ga from depleted harzburgitic–lherzolitic mantle tectonites. Chemical, petrological, and temporal links between the depleted mantle blocks, and the suite of magmatic blocks derived from partial melting and metasomatism of these depleted mantle blocks, unequivocally shows that they represent part of the same original Neoarchean fore-arc ophiolite suite. After formation and accretion in the oceanic realm, the melange was emplaced on the continental margin of the Eastern Block between 2.52 and 2.50 Ga, and underwent two stages of metamorphism at ca. 2.48–2.46 Ga and 1.81 Ga. Metamorphosed intermediate–mafic volcanic blocks exhibit systematic successive geochemical variations, from MORB-like to volcanic arc-like, and the N-MORB-like meta-basalts show remarkable similarity with the subduction initiation-related Izu–Bonin–Mariana (IBM) fore-arc basalts. We suggest that the Zunhua fore-arc complex records continuous geodynamic processes from subduction initiation to arc magmatism. The Zunhua ophiolitic melange is part of a ca. 2.5 Ga suture between an oceanic arc of the COB and Eastern Block of the NCC. After the arc–continent collision, an arc–polarity reversal event initiated a new eastward–dipping subduction zone on the western side of the COB. This arc–polarity reversal is traced for more than 1600 km along the length of the orogen, similar in scale, geometry, and duration between collision and polarity flip to the present-day arc–polarity reversal of the Sunda–Banda arc during its ongoing collision with the Australia continent. This indicates that a life cycle of an Archean subduction zone, including birth (subduction initiation), maturity (arc magmatism), death (arc-continent collision) and re-birth (arc–polarity reversal), is recorded in the Zunhua ophiolitic melange, and the geodynamics of plate tectonics at the end of the Archean was similar to those of today.

中文翻译：

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从俯冲开始到弧极反转：华北克拉通遵化蛇绿混杂岩太古代俯冲带的生命周期

摘要 在太古代岩石记录中很少发现俯冲开始和弧极反转。我们记录了沿华北克拉通 (NCC) 中央造山带 (COB) 东缘遵化蛇绿混杂岩的新太古代俯冲开始、前弧岩浆作用和弧极性反转事件。遵化蛇绿岩混杂岩是一个可测绘单元，其特征是变质的斜方辉石/二辉橄榄岩块、豆状铬铁矿含纯英岩、辉石岩、角闪岩、变玄武岩（玄武岩和辉绿岩）以及稀有的中间火山岩、燧石和带状铁构造的构造透镜，形成强烈的带状铁矿剪切变泥质基质。蛇绿混杂岩内岩浆块的新年代学和地球化学分析表明，地壳岩浆岩产于弧前区 2.55-2。52 Ga 来自贫化的斜纹辉石-重辉石地幔构造岩。枯竭地幔块与源自这些枯竭地幔块部分熔融和交代作用的岩浆块组之间的化学、岩石学和时间联系，明确表明它们代表同一原始新太古代前弧蛇绿岩组的一部分。混杂岩在海洋界形成和增生后，在 2.52 至 2.50 Ga 之间就位于东地块的大陆边缘，并在大约 2.52 和 2.50 Ga 之间经历了两个变质阶段。2.48-2.46 Ga 和 1.81 Ga。变质的中基性火山块表现出系统的连续地球化学变化，从 MORB 状到火山弧状，N-MORB 类变质玄武岩与俯冲起始相关的伊豆-博宁-马里亚纳 (IBM) 前弧玄武岩显示出显着的相似性。我们认为遵化弧前复合体记录了从俯冲开始到弧岩浆作用的连续地球动力学过程。遵化蛇绿混杂岩是约的一部分。２．５ ＣＯＢ大洋弧与ＮＣＣ东部地块之间的Ｇａ缝合线。弧-陆碰撞后，弧-极反转事件在COB西侧引发了一个新的东倾俯冲带。这种弧极反转沿造山带的长度追踪了 1600 多公里，在规模、几何形状和碰撞和极性翻转之间的持续时间与当前巽他 - 班达弧在其持续过程中的弧极反转相似与澳大利亚大陆相撞。