Spatio-temporal analysis of big data sets of detrital zircon U-Pb geochronology and Hf isotope data: Tests of tectonic models for the Precambrian evolution of the North China Craton

The formation mechanism of the North China Craton (NCC) is controversial, with one model (Model 1) sug- gesting that it was formed by progressive accretion of arcs by generally westward subduction in the Archean, then progressive outboard accretion via eastward subduction culminating in a N-S collision when the composite craton was amalgamated with the Columbia Supercontinent. In contrast, another popular model (Model 2) suggests that various coherent blocks collided in the Paleoproterozoic, forming a network of Paleoproterozoic (1.9-1.85 Ga) orogens with high-grade metamorphism defining the belts. Here, we test these contrasting models, using big data analysis of detrital zircons from well-exposed Precambrian massifs in the Mesozoic Taihang Mountains of the central NCC (CNCC), that cut across the boundaries of the sutures and tectonic zones proposed by the different models. The zircons record the magmatic and metamorphic history of the basement, and we use big data and spatio-temporal analysis techniques to test the along-strike variations in ages of magmatism and metamorphism, providing quantitative constraints as tests of the models.Simple age peaks can not represent the real magmatic intensity owing to preferential preservation. However, singularity indices, the time-varied indicators of power-law modeling, can characterize the spatiotemporal heterogeneity of mass distribution under unsteady trends. They can provide more stable and reliable time-series distributions. Our results show a multi-stage ladder-shaped evolutionary trend of epsilon Hf(t) values for igneous- originated detrital zircon during 3.7 to 1.5 Ga, representing progressive amalgamation of the craton, consis- tent with Model 1. The detrital zircon age singularity index series revealed three high-flux magmatic and two metamorphic events. The first magmatism and metamorphism occurred over almost the entire CNCC but was concentrated at its eastern margin, with an age peak at ca. 2.5 Ga. This event may have been caused by the arc-continent accretion along the eastern margin of the CNCC and the western margin of the Eastern Block as proposed by Model 1. The second magmatism developed primarily in the central CNCC, in the absence of contemporaneous metamorphism at ca. 2.15 Ga. This event reveals a local lithospheric extension that is probably a retroarc event from the convergent margin on the northern margin of the craton, as this event is recorded elsewhere in the NCC outside of the CNCC. The final magmatic event, with a violent fluctuation in the range of epsilon Hf(t) values and contemporaneous metamorphism, is almost absent in the central CNCC (only 6% data points) but spread throughout the northern and southern CNCC at ca. 1.85 Ga, and represents collisional assembly of the NCC with other outboard continental blocks representing the Columbia Supercontinent, also consistent with Model 1, but inconsistent with Model 2 that invokes the 1.85 collision to be along the full length of the CNCC, not only at its northern or southern margins. The westward migration of magmatic activity and high epsilon Hf(t) value centers after 2.5 Ga indicate the occurrence of a new east-dipping subduction system after collision of the Central (Wutai/Fuping) arc, and progressive migration of the orogenic front in the Paleoproterozoic.