We studied the stratigraphy, composition, and paleomagnetic properties of lateritic weathering profiles of Permian age from northern Iran and western Karakoram, Pakistan. A limited set of samples deemed representative yielded stable low-inclination paleomagnetic components carried essentially by hematite of chemical origin isolated in massive, fine-grained, and homogeneous ferricrete facies. These laterites originated at equatorial paleolatitudes characterized by intense weathering processes under warm and humid climatic conditions. Paleomagnetic estimates of paleolatitude from Iran, Karakoram, and north Tibet from this study and the literature, albeit sparse, provide testable constraints on the motion of the Cimmerian terranes as the result of the opening of the Neo-Tethys Ocean along the eastern margin of Gondwana during the Permian. We confirm and help refine previous suggestions that the Cimmerian terranes migrated from southern Gondwanan paleolatitudes in the Early Permian to subequatorial paleolatitudes by the Middle Permian – Early Triassic. As a novel conclusion, we find that timing, rates, and geometry of Cimmerian tectonics are broadly compatible with the transformation of Pangea from an Irvingian B to a Wegenerian A-type configuration with Neo-Tethyan opening taking place contemporaneously essentially in the Permian.

Quantitative compositional data from selected sandstone samples in the Upper Paleozoic to lowermost Triassic succession of the central Dolpo Tethys Himalaya (Thini Chu Group and base of the Tamba-Kurkur Formation) are relevant to understand the tectonic and climatic evolution of the northern margin of Gondwana from continental rift to break-up and spreading in the Neotethys Ocean. In central Dolpo, where the Upper Permian is thicker than in other sections of the Northern India and Nepal Tethys Himalaya, and sandstones occur both just below and above the Permian/Triassic boundary, the Thini Chu Group rests discon- formably over Lower Carboniferous carbonates. A terra rossa paleosoil documents a major hiatus that possibly spans the Visean to Early Bashkirian (“rift unconformity”). Another major unconformity overlain by the Murgabian-Midian? “Costiferina arenites” is interpreted as indicating final break-up and initial spreading in Neotethys (“break-up unconformity”). In fact, arenite lenses mantling the unconformity yielded euhe- dral grains of Cr-rich chromian spinel, indicating enhanced partial melting of the asthenosphere rising beneath the Northern India-Nepal “upper plate” margin. Regional correlations indicate a late Early Permian age for this event. LithoZones recognized within the Thini Chu Group are here correlated with formations recently established to the east in Manang (Nepal), largely according to their petrofacies. The Atali Quartzarenite (Petrofacies 1; “white quartzarenites”) best corresponds with the Bangba Fm. of Manang, whereas the “Costiferina arenites” (Petrofacies 2a), the “ochre pelites” and “estuarine quartzarenites” (Petrofacies 2b), and the “black shales and glauco-phosphorites” (Petrofacies 3, 4 and 5) are broadly coeval with Member C of the Puchenpra Formation. Detritai feldspars appear in the middle part of the Thini Chu Group (Petrofacies 2) and sharply and progressively increase upwards (Petrofacies 3), until they peak around the Permian/Triassic boundary (Petrofacies 4 to 5). This trend may be explained with continued uplift of rift shoulders after breakup, or rather with rapidly increasing aridity towards the close of the Permian, while Gondwana was shifting northwards toward the Southern Tropic. Arkosic composition around the Permian/Triassic boundary may be also consistent with an arid episode at global scale.