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Structural relationships in and around the Rheasilvia basin on Vesta
Journal of Structural Geology ( IF 3.1 ) Pub Date : 2022-07-07 , DOI: 10.1016/j.jsg.2022.104677
Hiu Ching Jupiter Cheng, Christian Klimczak

The Rheasilvia basin is an impact structure occupying most of Vesta's southern hemisphere. Divalia Fossae, a set of circum-equatorial troughs, were previously proposed to be concentric around the basin, which is widely regarded as evidence that the Rheasilvia impact directly caused the formation of the troughs. Here, we produce a structural map of Rheasilvia that allows for geologic interpretations and quantitative analyses of structure orientations and densities. We mapped basin-bounding scarps, scarps within the basin, ridges, and undefined lineaments. Scarps abound near the basin rim, with ridges being densely located on the basin floor near the central mound, forming a spiral pattern. This pattern is well-preserved on the basin floor except in the area superposing the older Veneneia basin, indicating that pre-existing Veneneia structures substantially influenced those of Rheasilvia. This implies that the lithosphere must have remained highly shattered after the Veneneia impact until Rheasilvia was emplaced. The Divalia Fossae cross-cut the Rheasilvia basin, and reanalysis of the geometric relationship between both landforms reveals that the troughs are not concentric around the basin center. These results are inconsistent with the previous hypothesis of trough formation and require a reconsideration of Vesta's tectonic history.



中文翻译:

灶神星 Rheasilvia 盆地及其周围的构造关系

Rheasilvia盆地是一个撞击结构,占据了灶神星南半球的大部分地区。Divalia Fossae 是一组环赤道槽,此前被提出与盆地同心圆,这被广泛认为是Rheasilvia 撞击直接导致槽形成的证据。在这里,我们制作了一张 Rheasilvia 的结构图,可以对结构方向和密度进行地质解释和定量分析。我们绘制了盆地边界陡坡、盆地内的陡坡、山脊和未定义的轮廓。盆地边缘处陡崖多,中丘附近的盆底处有山脊密集分布,呈螺旋状。除了与旧威尼斯盆地重叠的区域外,这种模式在盆地底部保存完好,表明预先存在的 Veneneia 结构极大地影响了 Rheasilvia 的结构。这意味着岩石圈在 Veneneia 撞击后一定保持高度破碎,直到 Rheasilvia 就位。Divalia Fossae 横切了Rheasilvia 盆地,对两种地貌的几何关系的重新分析表明,这些槽不是围绕盆地中心同心的。这些结果与先前的槽形成假设不一致,需要重新考虑灶神星的构造历史。再分析两种地貌之间的几何关系,发现槽不是围绕盆地中心同心的。这些结果与先前的槽形成假设不一致,需要重新考虑灶神星的构造历史。再分析两种地貌之间的几何关系,发现槽不是围绕盆地中心同心的。这些结果与先前的槽形成假设不一致,需要重新考虑灶神星的构造历史。

更新日期:2022-07-11
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