Singer et al. Europa Graben Data for JGR Planets Publication Titled "Thin Ice Lithospheres and High Heat Flows on Europa from Large Impact Structure Ring-graben"

These are the data associated with a Singer et al. manuscript submitted to the Journal of Geophysical Research - Planets. The title is "Thin Ice Lithospheres and High Heat Flows on Europa from Large Impact Structure Ring-graben". Publication information, including a DOI, will be updated upon completion of the peer review process.Abstract: Craters are probes of planetary surface and interior properties. Here we measure depths, widths, and spacing of circumferential ring-graben surrounding the two largest multiring impact structures on Europa, Tyre and Callanish. We estimate formation conditions including the ice shell structure. The radial extension necessary to form these graben is thought to be caused by asthenospheric drag of warmer, more ductile ice and/or water flowing towards the excavated center of the crater, under a brittle-elastic lithospheric lid. Measurements of graben depths from stereo-photoclinometric digital elevation models result in estimates of displacement, strain, and stress experienced by the ice shell. Graben widths are used to estimate the intersection depth of the bounding normal faults, a quantity related to the brittle-ductile transition depth that approximates elastic shell thickness during crater collapse. Heat flows at the time of crater formation as well as ice lithosphere and total shell thickness are thus also constrained. Average widths and depths tend to decrease with increasing distance from the structure center, while inter-graben spacing generally increases. Varied assumptions yield plausible total conductive ice shell thickness estimates between 4–8 and 2.5–5 km for Tyre and Callanish, respectively, and heat flows of ~70-115 (±30) mW m-2 for realistic thermal conductivities, consistent with other geophysical estimates for Europa. Higher heat flows are consistent with thin (≲10 km), conductive ice shells and impact breaching, or penetration of the stagnant lid for a convecting ice shell. Callanish, geologically younger, formed in a time or region of greater heat flow than Tyre.

本数据集关联于一篇已提交至《地球物理研究杂志：行星卷》（Journal of Geophysical Research - Planets）的Singer等人的研究手稿，其标题为《木卫二大型撞击构造环形地堑的薄冰岩石圈与高热流特征》（Thin Ice Lithospheres and High Heat Flows on Europa from Large Impact Structure Ring-graben）。包括数字对象标识符（Digital Object Identifier, DOI）在内的出版信息，将在同行评议流程完成后更新。摘要：撞击坑是探测行星表面与内部属性的有效探针。本文针对木卫二（Europa）上两处最大的多环撞击构造（multiring impact structures）——泰尔（Tyre）与卡拉尼什（Callanish），测量了其周围环形地堑（ring-graben）的深度、宽度与间距，并估算了包括冰壳结构在内的构造形成条件。此类地堑形成所需的径向扩张，被认为是在脆弹性岩石圈盖层（brittle-elastic lithospheric lid）之下，由温度更高、韧性更强的冰体及水体流向撞击坑挖蚀形成的中心区域的软流层拖曳作用所引发。基于立体光测斜数字高程模型（stereo-photoclinometric digital elevation models, DEM）对地堑深度开展测量，可估算冰壳所承受的位移、应变与应力。通过地堑宽度可估算其边界正断层（normal faults）的交汇深度，该参数与脆韧性转换深度（brittle-ductile transition depth）相关，近似对应撞击坑坍塌过程中的弹性壳厚度。因此，撞击坑形成时期的热流、冰岩石圈厚度与总冰壳厚度也可得到约束。地堑的平均宽度与深度往往随距构造中心距离的增加而减小，而地堑间距则总体呈增大趋势。基于不同假设条件，泰尔与卡拉尼什的总传导冰壳（conductive ice shell）厚度估算值分别为4~8 km与2.5~5 km；在合理热导率下的热流估算值约为70~115（±30）毫瓦每平方米，该结果与木卫二其他地球物理估算结果一致。更高的热流则与厚度≤10 km的传导型冰壳、撞击穿透（impact breaching）作用，或是对流冰壳（convecting ice shell）下停滞盖层（stagnant lid）的穿透现象相符。地质年代更年轻的卡拉尼什，形成于热流水平高于泰尔的时期或区域。