U-Pb dating of detrital zircons from the Wudangshan Group in the South Qinling and its geological significance

Abstract

U-Pb dating was made by the LA-ICP-MS method for detrital zircons from the Wudangshan volcanic-sedimentary succession in the South Qinling. Samples comprise quartz sandstones of the Wudangshan Group collected from the base of the Yangping Formation and an upper layer of the Shuangtai Formation overlain its volcanic sequence, and two river-sand collections from the drainage systems cutting across the two formations, respectively. The results show that the Yangping detrital zircons are dominated by 830-780 Ma grains with a minor population of ~1.0-0.84 Ga and sporadic grains of ~2.6, ~2.4 and 2.0 Ga, whereas the Shuangtai zircons yield an upper intercept age of 763±33 Ma, identical to the timing of the Wudangshan volcanism within error, with few concordant grains of 1.9 and 0.86 Ga. Age spectra for the two river-sand samples are similar to those of the Yangping and Shuangtai Formations, respectively. It thus suggests that the Wudangshan strata are less than 780 Ma, whereas their major detrital zircon populations of 1.0-0.85 Ga and 830-780 Ma are consistent with timing of the Hannan magmatic activities along the northwestern margin of the South China Block. This suggests a Hannan or adjacent area provenance for the Wudangshan strata. The Wudang area is characterized by rift-related igneous events at ~755 and ~680 Ma, respectively, pointing to a tectonomagmatic history different from the Hannan area. It is inferred that the ~755 Ma magmatism is likely to indicate a separation of the South China Block from the supercontinent Rodinia, while the ~680 Ma event suggests a further split between the South Qinling and some unknown continent. Detrital zircon, U-Pb geochronology, South Qinling, South China Block, Neoproterozoic evolution Citation:Ling W L, Duan R C, Liu X M, et al. U-Pb dating of detrital zircons from the Wudangshan Group in the South Qinling and its geological significance.

A ∼2.5 Ga magmatic event at the northern margin of the Yangtze craton: Evidence from U-Pb dating and Hf isotope analysis of zircons from the Douling Complex in the South Qinling orogen

“…Chen et al [20] recently identified emplacement ages of 2.7-2.6 Ga for A-type granites, which is similar to the age of 2693 ± 9 Ma obtained for the granite intrusion of the Yudongzi Group [21] and the protolith age of 2.75-2.70 Ga reported for the Huangluling granulite in the Dabie Mountain [22,23]. In fact, the age data of these three groups were also recorded in detrital zircons from metasedimentary rocks [5][6][7][8][9] and inherited zircons from igneous rocks [10][11][12][13][14] in different areas of the Yangtze craton, suggesting that the 3.3-3.2 Ga, 2.95-2.9 Ga and 2.7-2.6 Ga eras are important periods for the continental crustal growth in the Yangtze craton.…”

“…The growing amount of isotopic age data from Archean to Paleoproterozic, particularly the recently published U-Pb zircon ages, has led many researchers to suggest that Archean crystalline basement is widespread beneath the Yangtze craton [4]. However, the supporting evidence mainly comes from U-Pb studies of detrital zircons in metasedimentary rocks [5][6][7][8][9] or inherited zircons in igneous rocks [10][11][12][13][14]. The Archean age information obtained for the exposed basement rock series are mostly from the Kongling high grade metamorphic terrane at the northern margin of the Yangtze craton [15][16][17][18][19][20], with sporadic reports from the granulites in the Yudongzi Group and the Dabie Mountains [21][22][23].…”

Mesoproterozoic to Paleozoic Nd isotope stratigraphy of the South China continental nucleus and its geological significance

“…The SCB position in Rodinia reconstruction has received much attention, whereas the Nd isotope stratigraphy of the Yangtze continental nucleus presented here provides an additional constraint on this issue. The results of the present study also indicate that the formation process of the SCB and its history involved in Rodinia breakup are likely more complicated than previously proposed, including the number of micro continents merged into the unified SCB and the extent of the primary SCB before the breakup [62].…”

Discovery of Paleoproterozoic rapakivi granite on the northern margin of the Yangtze block and its geological significance

“…The lower intercept age (ca. 800 Ma) may represent the time when the rock suffered a later thermal event, which also is consistent with the time of Neoproterozoic tectonothermal events in the Yangtze block, or even over the entire South China area [54][55][56][57][58][59][60][61][62][63].…”