A purely structural restoration of the NFP20‐East cross section and potential tectonic overpressure in the Adula nappe (central Alps)
A purely structural restoration of the NFP20‐East cross section and potential tectonic overpressure in the Adula nappe (central Alps)
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NFP20-East 横截面的纯结构恢复和阿杜拉推覆体（阿尔卑斯山中部）潜在的构造超压
DOI：
10.1002/2013tc003409
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发表时间：
2014
期刊：
影响因子：
4.2
通讯作者：
Y. Podladchikov
中科院分区：
文献类型：
--
作者：
J. Pleuger;Y. Podladchikov
高压至超高压阿杜拉推覆体的常见挤压型模型要求该单元顶部有一个主要的正断层，这在构造记录中没有体现出来。这意味着这样一个正常断层存在，但在后来的变形阶段被完全抹去。然而，有证据表明减压发生在顶部至前陆逆冲期间。为了估算单个单元的埋藏深度，我们对NFP20 - East剖面的中心部分进行了新的纯结构运动学恢复，而无需在假定压力为静岩压力的情况下将岩石学压力数据转换为深度。结果表明，在构造变质史的几个阶段，大部分单元内的压力接近或略高于静岩压力。仅在阿杜拉推覆体的最大埋藏阶段，我们估计局部构造超压占静岩压力的40% ~ 80%。接受这样的超压，与理论上可能的值相比是温和的，阿杜拉推覆体可能没有俯冲到地壳下深度。我们认为，盆南推覆体的构造记录是相当完整的，构造超压的衰减是冲断过程中榴辉岩相向角闪岩相减压的可行解释。因此，始新世至渐新世阿尔卑斯山脉的发掘和收敛速度可能比先前假设的要小。
Common extrusion‐type models for the high‐ to ultrahigh‐pressure Adula nappe require a major normal fault along the top of this unit which is not conveyed in the structural record. This implies that such a normal fault existed but was completely erased during later deformational stages. However, there is evidence that decompression occurred during top‐to‐the‐foreland thrusting. We performed a new, purely structural kinematic restoration of the central part of the NFP20‐East cross section in order to estimate the burial depths of individual units without converting petrological pressure data into depth under the assumption that pressures were lithostatic. The results show that pressures within most of the units were close to but somewhat higher than lithostatic for several stages of the tectono‐metamorphic history. Only for the maximum burial stage of the Adula nappe, we estimate local tectonic overpressures of 40 to 80% of the lithostatic pressures. Accepting such an amount of overpressure, which is moderate compared to values theoretically possible, the Adula nappe was probably not subducted to subcrustal depth. We propose that the structural record of the Penninic nappe stack is quite complete and suggest that the decay of tectonic overpressure is a feasible explanation for decompression from eclogite‐ to amphibolite‐facies conditions during thrusting. Consequently, exhumation and convergence rates of the Eocene to Oligocene Alps may be smaller than previously assumed.
影响因子：
3.1
作者：
D. Herwartz;C. Münker;E. Scherer;T. Nagel;J. Pleuger;N. Froitzheim
通讯作者：
D. Herwartz;C. Münker;E. Scherer;T. Nagel;J. Pleuger;N. Froitzheim
高山造山运动从俯冲到碰撞热叠印的演化：阿尔卑斯山中部瓦莱桑洋的 40Ar/39Ar 年龄限制
影响因子：
4.2
作者：
M. Wiederkehr;M. Sudo;R. Bousquet;A. Berger;S. Schmid1
通讯作者：
S. Schmid1
通过碳质材料拉曼光谱对峰值变质条件进行 3D 评估：来自 Lepontine 圆顶边缘的示例（瑞士中部阿尔卑斯山）
影响因子：
2.3
作者：
M. Wiederkehr;R. Bousquet;M. Ziemann;A. Berger;S. Schmid
通讯作者：
S. Schmid