Dense hydrous magnesium silicate MgSiO_{4}H_{2} is widely regarded as a primary water carrier into the deep Earth. However, the stability fields of MgSiO_{4}H_{2} based on the prevailing structure model are narrower than experimental results at relevant pressure and temperature (P-T) conditions, casting doubts about this prominent mineral as a water carrier into the great depths of the Earth. Here, we report on an advanced structure search that identifies two new crystal structures, denoted as α- and β-MgSiO_{4}H_{2}, that are stable over unprecedentedly wide P-T conditions of 17-68 GPa and up to 1860 K, covering the entire experimentally determined range. Moreover, we performed x-ray diffraction measurements with backscattering electron image, combined with ab initio simulations, to demonstrate the formation of MgSiO_{4}H_{2} and AlOOH solid solutions that exhibit further enhanced P-T stability fields, making them robust carriers of water into the deepest lower mantle. These findings establish and elucidate the new MgSiO_{4}H_{2} phases as potential primary water carriers into the vast depths of the lower mantle, creating a distinct paradigm for the deep Earth water cycle.

中文翻译：

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新MgSiO_{4}H_{2}相作为潜在的主要水载体进入地球深处。


致密的含水硅酸镁MgSiO_{4}H_{2}被广泛认为是进入地球深处的主要水载体。然而，在相关压力和温度 （P-T） 条件下，基于主流结构模型的 MgSiO_{4}H_{2} 的稳定性场比实验结果窄，这使得人们对这种重要的矿物作为水载体进入地球深处产生了怀疑。在这里，我们报告了一项高级结构搜索，该搜索确定了两种新的晶体结构，分别表示为 α 和 β-MgSiO_{4}H_{2}，它们在 17-68 GPa 和高达 1860 K 的空前宽的 P-T 条件下保持稳定，涵盖了整个实验确定的范围。此外，我们使用背散射电子图像进行了 X 射线衍射测量，并结合从头开始模拟，以证明 MgSiO_{4}H_{2} 和 AlOOH 固体溶液的形成，这些固溶体表现出进一步增强的 P-T 稳定性场，使它们成为进入最深下地幔的坚固载体。这些发现建立并阐明了新的MgSiO_{4}H_{2}相，它们是进入下地幔广阔深处的潜在主要水载体，为地球深部水循环创造了一个独特的范式。