The main Karoo Basin of southern Africa contains the continental record of the end-Triassic, end-Permian, and end-Capitanian mass extinction events. Of these, the environmental drivers of the end-Capitanian are least known. Integrating quantitative stratigraphic architecture analysis from abundant outcrop profiles, paleocurrent measurements, and petrography, this study investigates the stratigraphic interval that records the end-Capitanian extinction event in the southwestern and southern main Karoo Basin and demonstrates that this biotic change coincided with a subtle variation in the stratigraphic architectural style ∼260 Ma ago. Our multi-proxy sedimentological work not only defines the depositional setting of the succession as a megafan system that drained the foothills of the Cape Fold Belt, but also attempts to differentiate the tectonic and climatic controls on the fluvial architecture of this paleontologically important Permian succession. Our results reveal limited changes in sediment sources, paleocurrents, sandstone body geometries, and possibly a constant hot, semi-arid paleoclimate during the deposition of the studied interval; however, the stratigraphic trends show upward increase in 1) laterally accreted, sandy architectural elements and 2) architectural elements that build a portion of the floodplain deposits. We consider this to reflect a long-term retrogradational stacking pattern of facies composition that can be linked to changes on the medial parts of southward draining megafans, where channel sinuosity increased, and depositional energy decreased at the end-Capitanian. The shift in the fluvial architecture was likely triggered by basin-wide allogenic controls rather than local autogenic processes because this trend is observed in the coeval stratigraphic intervals from geographically disparate areas in the southwestern and southern main Karoo Basin. Consequently, we propose that this regional backstepping most likely resulted from tectonic events in the adjacent Cape Fold Belt.

南部非洲主要的卡鲁盆地包含三叠纪末期，二叠纪末期和卡皮塔尼亚末期大灭绝事件的大陆记录。其中，最根本的是卡皮塔尼亚人的环境驱动因素。结合大量露头剖面，古流测量和岩相学的定量地层构造分析，本研究调查了记录西南和南部主要卡鲁盆地卡皮塔尼亚灭绝事件的地层间隔，并证明了这种生物变化与沙特阿拉伯的细微变化相吻合。大约260 Ma以前的地层建筑风格。我们的多代理沉积学研究不仅将演替的沉积环境定义为一个巨扇系统，该系统排干了Cape Fold带的山麓丘陵，但也试图区分这种古生物学上重要的二叠纪演替的河流构造上的构造和气候控制。我们的结果表明，在研究间隔的沉积过程中，沉积物来源，古流，砂岩体的几何形状以及有限的热，半干旱古气候变化有限。但是，地层趋势显示出以下方面的上升趋势：1）侧向沉积的沙质建筑元素； 2）构成洪泛区沉积物一部分的建筑元素。我们认为这反映了相组成的长期逆行堆积模式，该模式可能与向南排水的巨型扇形体中部的变化有关，那里通道的弯曲度增加，而卡皮塔尼期末沉积能量减少。河流构造的变化很可能是由盆地范围内的同种异体控制而不是局部自生过程触发的，因为这种趋势是在西南和南部主要卡鲁盆地地理上不同地区的同代地层间隔中观察到的。因此，我们认为，这种区域性退步很可能是由于邻近海角褶皱带的构造事件引起的。