Replication Data for: On the relative importance of thermal and chemical buoyancy in regular and impact-induced melting in a Mars-like planet

We ran several series of two-dimensional numerical mantle convection simulations representing in idealized form the thermochemical evolution of a Mars-like planet. In order to study the importance of compositional buoyancy of melting mantle, the models were set up in pairs of one including all thermal and compositional contributions to buoyancy and one accounting only for the thermal contributions. In several of the model pairs, single large impacts were introduced as causes of additional strong local anomalies, and their evolution in the framework of the convecting mantle was tracked. The models confirm that the additional buoyancy provided by the depletion of the mantle by regular melting can establish a global stable stratification of the convecting mantle and throttle crust production. Furthermore, the compositional buoyancy is essential in the stabilization and preservation of local compositional anomalies directly beneath the lithosphere and offers a possible explanation for the existence of distinct, long-lived reservoirs in the Martian mantle. The detection of such anomalies by geophysical means is probably difficult, however; they are expected to be detected by gravimetry rather than by seismic or heat flow measurements. The results further suggest that the crustal thickness can be locally overestimated by up to ∼20 km if impact-induced density anomalies in the mantle are neglected.

本研究开展了多组二维数值地幔对流模拟实验，以理想化形式复现类火星行星的热化学演化过程。为探究熔融地幔的成分浮力的重要性，模型以成对形式构建：一组纳入浮力的所有热与成分贡献项，另一组仅考虑热贡献项。在部分模型组中，引入单次大型撞击作为额外强局部异常的诱因，并追踪其在对流地幔框架内的演化过程。模拟结果证实，常规熔融导致地幔物质亏损所产生的额外浮力，可使对流地幔形成全球稳定的层结结构，并抑制地壳生成。此外，成分浮力对于稳定并保存岩石圈正下方的局部成分异常至关重要，同时可为火星地幔中独特且长期存续的储层的存在提供合理解释。不过，通过地球物理手段探测此类异常或存在较大难度，相较地震或热流测量，此类异常更有可能通过重力测量法被观测到。研究结果还表明，若忽略地幔中撞击诱发的密度异常，局部地壳厚度的估算值最高可被高估约20千米。