Ghost-arc geochemical anomaly at a spreading ridge caused by supersized flat subduction.
Ghost-arc geochemical anomaly at a spreading ridge caused by supersized flat subduction.
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DOI：
10.1038/s41467-023-37799-w
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发表时间：
2023-04-12
影响因子：
16.6
通讯作者：
Zlotnik, Sergio
中科院分区：
文献类型：
--
作者：
Gianni, Guido M.;Likerman, Jeremias;Navarrete, Cesar R.;Gianni, Conrado R.;Zlotnik, Sergio
南大西洋-西南印度洋脊（SASWIR）拥有大洋中脊玄武岩，其残留的与俯冲相关的地球化学指纹（即鬼弧特征）来源不明。在这里，我们通过对板块运动学重建和地震层析成像模型的分析表明，SASWIR俯冲修正的地幔源形成于侏罗纪靠近乔治亚群岛板片（GI）的地方，并在地幔参考系中保持近乎静止。在本次分析中，GI 位于侏罗纪巴塔哥尼亚-南极半岛活动边缘内侧较远的地方。此前这被归因于晚三叠世-早侏罗世的一次大规模平坦俯冲事件。我们认为，在这个平板阶段，中生代活动边缘和周围缝合带下方的俯冲改变地幔区域可能已经被推平到内陆超过 2280 公里。平板消亡后，这种地幔异常保持接近静止状态，并于 1.83 亿年前（Myr）被卡鲁地幔柱采样，并自 55 Myr 前起再次被 SASWIR 采样。我们将这个过程称为软流圈异常伸缩。这项研究提供了迄今为止未被认识的平坦俯冲的地球动力学效应，我们通过数值模拟支持其可行性。南大西洋-西南印度洋脊拥有大洋中脊玄武岩，具有残留的与俯冲相关的地球化学特征，其起源尚未解决。该研究表明，这与通过大规模平板事件向内陆迁移超过 2280 公里的俯冲改变地幔有关。
The Southern Atlantic-Southwest Indian ridges (SASWIR) host mid-ocean ridge basalts with a residual subduction-related geochemical fingerprint (i.e., a ghost-arc signature) of unclear origin. Here, we show through an analysis of plate kinematic reconstructions and seismic tomography models that the SASWIR subduction-modified mantle source formed in the Jurassic close to the Georgia Islands slab (GI) and remained near-stationary in the mantle reference frame. In this analysis, the GI lies far inboard the Jurassic Patagonian-Antarctic Peninsula active margin. This was formerly attributed to a large-scale flat subduction event in the Late Triassic-Early Jurassic. We propose that during this flat slab stage, the subduction-modified mantle areas beneath the Mesozoic active margin and surrounding sutures zones may have been bulldozed inland by >2280 km. After the demise of the flat slab, this mantle anomaly remained near-stationary and was sampled by the Karoo mantle plume 183 Million years (Myr) ago and again since 55 Myr ago by the SASWIR. We refer to this process as asthenospheric anomaly telescoping. This study provides a hitherto unrecognized geodynamic effect of flat subduction, the viability of which we support through numerical modeling. The Southern Atlantic-Southwest Indian ridges hold mid-ocean ridge basalts with a residual subduction-related geochemical signature, whose origin is unsolved. The study suggests a link to a subduction-modified mantle transported inland >2280 km by a large-scale flat slab event.
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影响因子：
3.9
作者：
Cerpa, Nestor G.;Sigloch, Karin;Mihalynuk, Mitchell G.
通讯作者：
Mihalynuk, Mitchell G.
影响因子：
5.8
作者：
Copeland, Peter;Currie, Claire A.;Murphy, Michael A.
通讯作者：
Murphy, Michael A.
影响因子：
3.9
作者：
Dai, Liming;Wang, Liangliang;Yu, Shengyao
通讯作者：
Yu, Shengyao
影响因子：
4.6
作者：
Gianni, Guido M.;Navarrete, Cesar;Spagnotto, Silvana
通讯作者：
Spagnotto, Silvana
DOI：
10.1098/rsta.2002.1077
发表时间：
2002-11-15
影响因子：
5
作者：
Grand, SP
通讯作者：
Grand, SP