The Tibesti Volcanic Province (TVP) in northwest Chad represents the second largest of the five Gharyan–Tibesti volcanic provinces and covers an area around 29,000 km². The other four provinces are in Libya, but all five provinces are from late Miocene to Quaternary and may have a common mantle source. The TVP, however, differs from the other four as regards volcano-tectonic processes, eruption style, and production of volcanic materials. The volcanic products of the TVP were erupted from the end of Miocene to late Pleistocene, range from basaltic to acidic, and suggest a double magma source – a shallow chamber fed by a deeper and larger reservoir. More specifically, field observations and numerical modelling results suggest that the basaltic magmas forming scoria cones, primarily at the periphery of the TVP, came from a deeper magma reservoir in the lower crust while the rhyolite and ignimbrites were fed by a shallow crustal magma chamber. By contrast, the volcanic products of the four volcanic provinces in Libya are primarily basalts and fed directly from single deep reservoirs. In the period from 8 Ma to 7−5 Ma, the evolution of the TVP was characterised by the formation of central volcanoes. Subsequently, in the period from 7−5 Ma to 0.43 Ma, the TVP was subject to caldera collapses that produced large-volume ignimbrites (>100 km³). Here we present numerical models with plausible loading conditions to understand better the volcano-tectonic evolution of the TVP and the spatial and temporal distribution of its major volcanic units. Our results suggest that the normal local stress field encouraged the formation of a central-volcano edifice (a volcanic cone) fed by radial dykes and inclined sheets and mostly erupting small volumes. By contrast, stress fields generated as a result of small crustal uplift or doming, due to the accumulation of magma in a deep-seated reservoir, triggered the formation of a ring-fault and the injection of a ring-dyke above the lateral margins of a shallow crustal magma chamber. Subsequently, the piston-like caldera subsidence helped to squeeze magma out of the shallow chamber resulting in large eruptions.

乍得西北部的提贝斯蒂火山省（TVP）代表了加里扬－提贝斯蒂五个火山省中的第二大省，面积约29,000 km ²。其他四个省位于利比亚，但所有五个省都从中新世晚期到第四纪，可能有共同的地幔来源。然而，TVP在火山构造过程，喷发方式和火山材料生产方面与其他四个不同。TVP的火山产物从中新世末期到晚更新世爆发，范围从玄武岩到酸性，并暗示着双重岩浆源–浅室，由更深和更大的储层提供。更具体地说，现场观察和数值模拟结果表明，形成矿渣锥的玄武岩浆主要来自TVP的外围，来自下地壳中较深的岩浆储层，而流纹岩和火成岩则由一个浅的地壳岩浆室供给。相比之下，利比亚四个火山省的火山产物主要是玄武岩，直接从单个深层储层中获取。在8 Ma至7-5 Ma期间，TVP的演化以中央火山的形成为特征。随后，在7−5 Ma至0.43 Ma的时间段内，TVP遭受了破火山口坍塌的作用，产生了大块的火成岩（> 100 km³）。在这里，我们提供具有合理载荷条件的数值模型，以更好地了解TVP的火山构造演化及其主要火山单元的时空分布。我们的研究结果表明，正常的局部应力场会鼓励由径向堤坝和倾斜的片层（主要是少量喷发）形成的中央火山大厦（火山锥）的形成。相比之下，由于深部储层中岩浆的堆积，由于地壳小隆起或隆起而产生的应力场触发了断层的形成，并在其侧缘上方注入了环堤。浅地壳岩浆室。随后，类似活塞的破火山口下沉帮助将岩浆从浅室中挤出，导致大爆发。