Latest Pliocene to recent thick-skinned tectonics at the Upper Rhine Graben – Jura Mountains junction
Latest Pliocene to recent thick-skinned tectonics at the Upper Rhine Graben – Jura Mountains junction
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莱茵河上游地堑 - 汝拉山脉交界处最新的上新世到最近的厚皮构造
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
S. Schmid
中科院分区：
文献类型：
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作者：
K. Ustaszewski;S. Schmid
最南端的上莱茵河地堑和邻近的汝拉经历了基底缩短，发生在上新世河流“Sundgau砾石”沉积之后。影响这些砾石基底的褶皱系统地走向NE至ENE。从反射地震线和等高线图的基础第三纪和基础上新世水平的综合证据表明，这些褶皱可能形成的NNE-SSW和WSW-ENE走向的断层厚皮复活。这种厚皮缩短是NW-SE方向的，即平行于从地震构造推断的最大水平应力。北北东-南西西向断层（平行于上莱茵河地堑）以左旋走滑方式重新活动。然而，属于莱茵河-布雷斯转换带的WSW-ENE向断层的右旋逆冲再活化被解释为占主导地位。最近的河道在EN-Echelon对齐的表面背斜顶部周围的偏转表明，变形目前正在进行中。影响Sundgau砾石基底的褶皱的后向变形表明水平位移速率约为0.05 mm/a。这相当于最小应变速率约为2·10−16 s−1，给出了这种变形的最大时间跨度为2.9 Ma，即生物地层学确定的砾石最小年龄。据推测，从汝拉褶皱主要阶段盛行的薄皮构造到很可能仍在进行的厚皮构造的变化发生在上新世晚期。我们推测，这种变化可能与一般的阿尔卑斯山前陆内的石炭二叠纪槽的初期反转。这种沿西北-东南向基底断层（莱茵-布雷斯转换带的一部分，在石炭-二叠纪海槽的形成过程中被预构造）的右旋平移或纯压缩模式沿着反转可能引发了1356年巴塞尔地震。
The southernmost Upper Rhine Graben and adjacent Jura experienced basement-rooted shortening that occurred after the deposition of the Pliocene fluvial “Sundgau gravels”. Folds affecting the base of these gravels systematically trend NE to ENE. Combined evidence from reflection seismic lines and contour maps of the base-Tertiary and base-Pliocene levels indicates that these folds probably formed by thick-skinned reactivation of both NNE-SSW and WSW-ENE-striking faults. This thick-skinned shortening is NW-SE oriented, i.e. parallel to the maximum horizontal stresses inferred from seismotectonics. NNE-SSW-striking faults (paralleling the Upper Rhine Graben) have been reactivated in sinistral strike-slip mode. However, dextrally transpressive reactivation of the WSW-ENE-trending faults that belong to the Rhine-Bresse Transfer Zone is interpreted to predominate.Deflections of recent river courses around the crests of en-échelon-aligned surface anticlines suggest that the deformation is ongoing at present. Retro-deformation of the folds affecting the base of the Sundgau gravels indicates horizontal displacement rates of about 0.05 mm/a. This corresponds to a minimum strain rate in the order of 2·10−16 s−1, given the maximum time span of 2.9 Ma for this deformation, i.e. the biostratigraphically determined minimum age of the gravels. A change from thin-skinned tectonics, that prevailed during the main phase of Jura folding, to very probably still ongoing thick-skinned tectonics is inferred to have occurred in the Late Pliocene. We speculate that this change might be linked to the incipient inversion of Permo-Carboniferous troughs within the Alpine foreland in general. This inversion in dextrally transpressive or purely compressive mode along a WNW-ESE-trending basement fault, that is part of the Rhine-Bresse Transfer Zone, which in turn was prestructured during the formation of the Permo-Carboniferous troughs, could have triggered the 1356 Basel earthquake.