Quantifying the Structure and Extension Rate of the Linfen Basin, Shanxi Rift System Since the Latest Miocene: Implications for Continental Magma‐Poor Rifting

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 26 Al/ 10 Be 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. Continental rifting is an important part of plate tectonics. Scientists are still trying to understand how magma‐poor continental rifts happen because the tectonic forces available are not enough to stretch the strong lithosphere (outer layer of the Earth). We take the Linfen Basin (LB) in the magma‐poor Shanxi Rift System (SRS) in North China as an example to study this issue. We find the basin bottom ages are about 6.1 million years in the south and 4.2 million years in the north, indicating northward propagation of the rift basin. The basin extended by about ∼3.6 km at an average rate of 0.9 km per million years. Not only the LB but also the circum‐Ordos basins are rotating accordantly. We propose a basin‐scale non‐rigid transtensional bookshelf faulting mode