Quantifying the Structure and Extension Rate of the Linfen Basin, Shanxi Rift System Since the Latest Miocene: Implications for Continental Magma‐Poor Rifting
Quantifying the Structure and Extension Rate of the Linfen Basin, Shanxi Rift System Since the Latest Miocene: Implications for Continental Magma‐Poor Rifting
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DOI：
10.1029/2023tc007885
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发表时间：
2023-09
期刊：
影响因子：
4.2
通讯作者：
Peng Su;Honglin He;Yiduo Liu;F. Shi;D. Granger;Eric Kirby;Lan Luo;Fei Han;R. Lu
中科院分区：
文献类型：
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作者：
Peng Su;Honglin He;Yiduo Liu;F. Shi;D. Granger;Eric Kirby;Lan Luo;Fei Han;R. Lu
缺乏岩浆的大陆裂谷的形成是一个神秘的过程，因为在没有岩石圈温度升高的情况下，克拉通岩石圈的弱化机制仍然不确定。一种观点将变弱与隐藏在深处的融化联系起来，而另一种观点则将其归因于预先存在的弱点。长期伸展速率也影响岩石圈强度和裂谷演化。我们以华北克拉通岩浆匮乏的山西裂谷系（SRS）中的临汾盆地（LB）为研究对象来了解这些成分。对盆地3个深孔不同深度的14个岩心样品进行了宇宙成因26Al/10Be埋藏定年，得到了6个有效埋藏年龄，范围为2.37+1.18/−1.21 ~ 5.86+inf/−1.37 Ma。我们进一步重新解释了地震反射剖面，并通过基于伸展断层弯曲褶皱理论的多重约束正演构造建模，量化了伸展的几何形状和数量。据估计，南段和北段的基底沉积时间分别为~ 6.1和~ 4.2 Ma，表明裂陷是历时性的，向北扩展。扩展的量和平均速率分别为~ 3.6 km和~ 0.9 km/Myr。盆地深度向北增加表明盆地呈顺时针方向旋转。我们提出了一个盆地尺度的非刚性张拉式书架断裂模型来解释环鄂尔多斯盆地的旋转模式。我们认为继承构造削弱了SRS的克拉通岩石圈，低伸展率导致了其岩浆贫乏的性质。我们提出了一个岩石圈尺度的LB演化模型，该模型调用了继承的地壳软弱、低伸展率和较低的岩石圈逆流。
The formation of magma‐poor continental rifts is an enigmatic process, as the weakening mechanism(s) for cratonic lithosphere remains uncertain in the absence of elevated lithospheric temperature. One view links weakening to melts hidden at depth, while another ascribes it to pre‐existing weaknesses. Long‐term extensional rates also influence lithospheric strength and rift evolution. We target the Linfen Basin (LB) in the magma‐poor Shanxi Rift System (SRS) in the North China Craton to understand these components. We apply cosmogenic 26Al/10Be burial dating on 14 core samples at different depths from three deep boreholes in the basin and obtain six valid burial ages ranging from 2.37+1.18/−1.21 to 5.86+inf/−1.37 Ma. We further re‐interpret a seismic reflection profile and quantify the geometry and amount of extension by forward structural modeling with multiple constraints based on extensional fault‐bend folding theory. The timing of the basal sedimentation is estimated to be ∼6.1 and ∼4.2 Ma in the southern and northern portions, respectively, indicating diachronous, northward‐propagating rifting. The amount and mean rate of extension are ∼3.6 km and ∼0.9 km/Myr, respectively. The basin depths increasing northward indicates the clockwise rotation of the basin. We propose a basin‐scale non‐rigid transtensional bookshelf faulting model to explain the rotation patterns of the circum‐Ordos basins. We argue that the inherited structures weaken the cratonic lithosphere of the SRS, and the low extension rate contributes to its magma‐poor nature. We propose a lithospheric‐scale evolution model for the LB, invoking the inherited crustal weakness, low extension rate, and lower lithosphere counterflow.