Table S1.xlsx

Striking changes in kinematics and deformation styles often occur in convergent orogens in the later stages of their tectonic evolution, such as in the southeastern Tibetan Plateau, which transitioned from transpression to transtension and experienced kinematic reversal on regional fault systems since the Miocene, approximately 40 Ma after the initial collision. Although this shift has long been identified, the spatial patterns of onset and driving mechanisms are unclear, hindering an understanding of the processes and dynamics of intracontinental orogeny. We target the NW Yunnan basin region in the SE Tibetan Plateau. We conduct an integrative study of apatite (U-Th)/He and fission track thermochronology along with structural and sedimentary analysis to decipher the structural evolution of this region. Nearly E-W-directed shortening may have occurred during the Eocene to Oligocene, forming various-scale thrust and fold systems, widespread exhumation, and topographic uplift. Combined with existing data, this region has undergone a transition to transtension during the late Miocene-Pliocene, forming basin-and-range style landscapes. Furthermore, we explore the crustal deformation patterns and kinematics of major active faults based on newly processed geophysical data. Thickened crust in a hyper-oblique convergent zone would raise the temperature at depth and weaken the long-term strength of the upper mantle, especially in the presence of water. Such lithospheric conditions are more prone to localized tectonics and can cause late-stage orogenic gravitational collapse, driving striking structural transitions in the NW Yunnan basin region.

汇聚造山带（convergent orogens）在构造演化的晚期阶段通常会出现运动学（kinematics）与变形样式（deformation styles）的显著变化，以青藏高原东南部（southeastern Tibetan Plateau）为例：该区域自中新世（Miocene）以来（约初始碰撞后40 Ma），由压扭（transpression）环境转变为张扭（transtension）环境，并在区域断裂系统上发生了运动学反转（kinematic reversal）。尽管这一转变早已被识别，但其启动的空间分布模式与驱动机制仍不明确，这阻碍了人们对陆内造山作用（intracontinental orogeny）过程与动力学机制的认识。我们以青藏高原东南部的滇西北盆地区域为研究对象，整合开展磷灰石（U-Th）/氦热年代学、裂变径迹热年代学（fission track thermochronology）以及构造与沉积分析（structural and sedimentary analysis），以解析该区域的构造演化过程。始新世（Eocene）至渐新世（Oligocene）期间，区域可能发生了近东西向挤压（E-W-directed shortening），形成了不同尺度的逆冲褶皱系统（thrust and fold systems）、广泛的剥露作用与地形抬升（topographic uplift）。结合现有数据可知，该区域在晚中新世-上新世（late Miocene-Pliocene）期间发生了向张扭环境的转变，形成了盆岭型地貌（basin-and-range style landscapes）。此外，我们基于新处理的地球物理数据（geophysical data），探究了主要活动断裂（major active faults）的地壳变形模式（crustal deformation patterns）与运动学特征。高斜向汇聚带（hyper-oblique convergent zone）中的增厚地壳会提升深部温度，削弱上地幔（upper mantle）的长期强度，在有水参与的情况下尤为显著。此类岩石圈条件更易引发局部构造活动，并可造成造山晚期的重力崩塌（gravitational collapse），进而驱动滇西北盆地区域发生显著的构造转变。