Sr–Nd–Pb isotope mapping of Mesozoic igneous rocks in NE China: Constraints on tectonic framework and Phanerozoic crustal growth

New Sr–Nd–Pb isotope dataset of Mesozoic igneous rocks shows that the NE China can be subdivided into four Sr–Nd–Pb isotope provinces: (1) the northern Hinggan Mountains (NHM) region; (2) the southern Hinggan Mountain (SHM)–Yanji-Liaoyuan (YL) region; (3) the Zhangguangcai Range–Jiamusi (ZGJ) Block; and (4) the exotic Wandashan massif (WDM). The Wandashan massif contains Mesozoic (high-μ)-type oceanic island basalts (HIMU-OIBs) with highly radiogenic Pb isotopic compositions (e.g., 206Pb/ 204Pb(i) = 18.9–22.7), quite different from other regions that have moderately radiogenic Pb (i.e., 206Pb/ 204Pb(i)) is generally less than 18.6. These HIMU-OIBs also show negative Δ7/4 and Δ8/4 values, signatures of Southern Gondwanaland Continent. By contrast, the majority of Mesozoic igneous rocks in other areas of NE China have positive Δ7/4 and Δ8/4 values, akin to the Northern Laurasian Continent. Such isotopic variations were probably due to the enrichment processes mainly caused by Paleozoic Paleo-Asian ocean subduction and to some extent by subduction of the Paleo-Pacific Ocean since early Mesozoic. The mantle-derived rocks in the NHM region is characterized by moderately radiogenic Nd and Pb isotopic compositions (ε Nd(t) = −0.2 to + 3.6 and 206Pb/ 204Pb(i) = 18.3–18.6). Compared with the NHM region, the mantle-derived magmas in the SHM–YL region show wider Nd isotopic variation (ε Nd(t) = −1.1 to + 6.6) and less radiogenic Pb ( 206Pb/ 204Pb(i) = 18.1–18.4). Along the Hegenshan-Solonker suture distributes an early Cretaceous felsic magmatic belt with highly positive-ε Nd (ε Nd(t) = + 4.0 to + 5.9) and radiogenic Pb compositions ( 206Pb/ 204Pb(i) = 18.4–18.6), suggesting that it was not only an important Phanerozoic crustal growth belt but also a zone containing significant volume of pelagic sediments or their metamorphosed derivates. Adjacent to the Hengenshan ophiolite occurs a suite of andesites showing nonradiogenic Nd (ε Nd(t) = −10.5 to −6.3) and Pb ( 206Pb/ 204Pb(i) = 17.22–17.26), as well as DUPAL Pb isotopic signatures. These features indicate the existence of “old” lower continental crust beneath the area. Compared with the majority of crust-derived rocks in the NHM and SHM–YL regions (ε Nd(t) = −2.9 to + 6.8 and 206Pb/ 204Pb(i) = 17.4 to 18.6), the Mesozoic granitoids in the ZGJ block have relatively less radiogenic Nd (ε Nd(t) = −2.9 to + 2.1) and more radiogenic Pb composition ( 206Pb/ 204Pb(i) = 18.2 to 18.9). Considering that the Paleozoic granitoi