Provenance Evolution of Age‐Calibrated Strata Reveals When and How South China Block Collided With Gondwana

Abstract

The South China Block (SCB) has been regarded by many as an integral part of Gondwana, but proposed timing and processes for its accretion to Gondwana vary and remain contentious, largely owing to the lack of reliable Pan-African age paleomagnetic data and tectono-magmatic records from the SCB. Integrated in situ U-Pb ages and Hf-O isotope analyses of detrital zircons from geochronologically well-calibrated Ediacaran-Cambrian sedimentary rocks of western SCB reveal age populations of 2.51, 1.85, 1.20, 0.80, and 0.52 Ga. Detrital zircon age spectra indicate a major tectonic transition for the SCB during 0.56-0.54 Ga, interpreted to reflect the beginning of the collision between SCB-Indochina and NW India blocks. The collisional event lasted until early Ordovician, leading to the suturing of the SCB-Indochina to the northern margin of East Gondwana. Plain Language Summary The South China Block is thought to be a part of the Gondwana superterrane, which was composed of more than half of all continents 650-400 million years ago (Ma). However, questions of when and how the South China Block collided with Gondwana are yet to be answered. In this study, we conducted provenance analyses of sedimentary rocks whose depositional ages were known via radioisotopic dating and chemo-biostratigraphy in the western South China Block. The results reveal a change in tectonic setting of the South China Block at 560-540 Ma, interpreted as the onset of the collision between the South China Block and India along the northern margin of East Gondwana.

Late Triassic foreland basin and Early Palaeozoic basement in the eastern Yidun Micro‐block and its tectonic implications for the eastern Palaeo‐Tethys

“…(a) Detrital zircon U–Pb age spectra and corresponding kernel density estimation of the alleged lower Tumugou Formation, the upper Tumugou Formation, and the Lamaya Formation in this study. (b) Relative probability plots of detrital zircon ages for Ediacaran‐Cambrian sedimentary rocks of South China Block, Indochina Block, Australia, Himalaya, and Iran (modified after Su et al (2019) and C. Yang, Li, Li, Zhu, and Lu (2020))…”

New detrital zircon U–Pb insights on the palaeogeographic origin of the central Sanandaj–Sirjan zone, Iran

“…The Grenvillian detrital age population suggests that the 'Gondwana superfan' even spread detrital material far east along the northern Gondwana margin and reached the South China block, where this age group occurs but remains subordinate (e.g. Yang et al 2020). (4) It is worth noting that further research should focus on more detrital zircon ages from metamorphic clastic rocks and Cambrian-Ordovician sandstones as well as obtaining the biogeographic distribution of Cambrian-Ordovician shallow marine organisms that would also provide better insights into the palaeogeographic reconstruction of the northern Gondwana margin during early Palaeozoic time.…”

“…For the interpretation of our results, we integrate our new data with the previously published detrital zircon U-Pb data from other Precambrian-Palaeozoic clastic sediments throughout the Alborz, Central Iran and NE Iran. We juxtapose the new detrital U-Pb zircon data with biogeographic evidence to constrain the position of the Iranian microcontinent on the northern Gondwana margin and its relation to the global framework as was recently also postulated by Yang et al (2020) and Merdith et al (2021). We show that the SSMZ as part of the Iranian microcontinent bears similar detrital zircon age spectra to those known from the Arabian-Nubian shield, in peri-Gondwanan terranes to the west of Iran as well as to those of the South China block in the east.…”

“…Note the potential close neighbourhood of South China and Central Iran/SSMZ at similar latitudes assuming that the units could be freely shifted along latitudes (because of the undetermined longitude). (b) This reconstruction according to Yang et al (2020) puts the South China block in East Gondwana. Red double arrow indicates the palaeobiogeographic relationships.…”

“…In summary, late Neoproterozoic to the early Silurian faunas, restricted to the same type of palaeoenvironment, are shared by the Iranian microcontinent and South China block and represent key elements to determine their palaeogeographic similarities along the Gondwanan margin (Figs 10,11). Li et al (2014) and Yang et al (2020) proposed that the South China block was accreted to East Gondwana during late Neoproterozoic-Cambrian times. Consequently, the Iranian microcontinent including the SSMZ can be considered as being part of the same Cambrian-early Silurian Gondwanan margin.…”