AI 中文总结
本研究通过三维热-力学模拟，揭示法属小安的列斯群岛俯冲启动阶段变形与热结构的相互作用，发现其热结构受启动过程强烈影响，存在火山弧启动的潜在位置。
AI 中文摘要
我们采用三维热-力学模拟研究俯冲带启动及早期热演化的条件，重点关注小安的列斯群岛区域。我们的模型施加的汇聚速率为2厘米/年，纳入了地幔与地壳岩石不可逆变形产生的加热效应，采用弹性、蠕变及非关联塑性流动定律。研究结果显示，洋壳板片形成前的变形加热强度超乎预期。数百万年后，由不可逆变形引发的屈曲与加热形成了独特的地形与地表热流模式，尽管洋壳板片及俯冲界面尚未完全发育，该模式仍与现今观测结果相似。在加勒比板块内部，板块屈曲形成了一条高大的地形脊，其下方存在一个以莫霍面正下方为中心的大型正热异常，幅度约200开尔文。将热量传递至地表的传导热边界层在地形最高点下方从约100公里变薄至10公里，使得该脊能抬升至海平面以上。该热结构表明，在距板块间接触带约180公里处存在火山弧启动的可能性。30-50公里深度的热区压力与从小安的列斯群岛原生岩浆推断出的压力一致，若存在挥发分，该区域是加勒比地幔部分熔融最可能的位置。厚度约20-25公里的加勒比厚地壳也被加热至足以产生硅质熔体的程度。推断的岩石圈厚度为50-100公里，与层析成像研究结果一致。因此，俯冲热结构受数百万年启动过程的强烈影响。
英文摘要
We used 3-D thermomechanical modelling to investigate conditions during subduction-zone initiation and early thermal development with focus on the Lesser Antilles. Our model imposes a convergence velocity of 2 cm per year and incorporates heating caused by irreversible deformation of mantle and crustal rocks, using elasticity, creep, and non-associative plastic flow laws. Our results show that deformational heating before slab development is unexpectedly strong. After several million years, buckling and heating due to irreversible deformation create distinctive patterns of topography and surface heat flow that resemble present-day observations, despite the slab and subduction interface being incompletely developed. Within the Caribbean plate, plate buckling produces a high topographic ridge underlain by a large positive thermal anomaly of approximately 200 K, centred just below the Moho. The conductive thermal boundary layer transporting this heat to the surface thins from about 100 km to 10 km beneath the topographic maximum, allowing the ridge to rise above sea level. This thermal structure suggests the potential initiation of a volcanic arc approximately 180 km from the inter-plate contact. A hot zone at 30-50 km depth has pressures consistent with those inferred from Lesser Antilles primitive magmas and represents the most plausible location for partial melting of Caribbean mantle if volatiles are present. The thick Caribbean crust, approximately 20-25 km, is also heated sufficiently for possible silicic melt generation. The inferred lithospheric thickness of 50-100 km aligns with tomography studies. Thus, subduction thermal structure is strongly influenced by several million years of initiation processes.
