Pre-Cryogenian stratigraphy, palaeontology, and paleogeography of the Tibetan Plateau and environs

Abstract

<p>The composition and geological evolution of pre-Cryogenian material in the Tibetan Plateau and its surrounding areas have played an important role in studying the formation and evolution of early supercontinents on Earth. This paper systematically summarizes the characteristics of pre-Cryogenian sedimentation, paleontology, magmatism, and metamorphism in the Tibetan Plateau and its surrounding areas. Based on existing data, the records of pre-Cryogenian sedimentation and paleontology are mainly concentrated in the Meso–Neoproterozoic, with relatively few records from the Paleoproterozoic or earlier. The oldest geological record is the Hadean detrital zircons in the metamorphosed sedimentary rocks of the Himalaya and Qamdo areas (ca. 4.0 Ga). The Tibetan Plateau and surrounding areas preserve records related to the formation and evolution of the Kenor supercraton, and the Columbia, Rodinia, and Gondwana supercontinents. Pre-Cryogenian basements can be divided into three types: Tarim-, Yangtze-, and Lhasa-type. The Tarim-type basement has a paleogeographic affinity with the northern margins of the Australian and Indian continents and lacks detrital zircon age peaks and magmatic-metamorphic records related to the Rodinia assembly (ca. 1.3–0.9 Ga). The Yangtze-type basement records volcanic activity related to global cooling in the latest pre-Cryogenian period and contains Meso–Neoproterozoic stromatolite and micropaleoflora fossils, as well as magmatic-metamorphic records related to Rodinia assembly (ca. 1.1–1.0 Ga). The Lhasa-type basement is characterized by Neoproterozoic rift-related sediment records (ca. 900 Ma) and high-pressure metamorphic events (ca. 650 Ma), with a prominent peak of detrital zircon ages of ca. 1.2–1.1 Ga. It is likely to have a paleogeographic affinity with the African continent.</p>