Tonalite-Trondjemite-Granodiorite (TTG) rocks are the most important Archean geological records in the North China Craton (NCC) which has had a long geological history back to ca. 3. 8Ga ago. Eoarchean (3. 6 similar to 4. 0Ga) TTGs have only been identified in the Anshan-Benxi (Anben) area, although abundant 3. 6 similar to 3. 88Ga detrital zircons were discovered in several types of metasedimentary rocks in eastern Hebei; Paleoarchean (3. 2 similar to 3. 6Ga) TTGs occur in Anben, eastern Hebei and Xinyang; Mesoarchean (2. 8 similar to 3. 2Ga) TTGs occur in Anben, eastern Hebei, eastern Shandong and Lushan. Early Neoarchean (2.6 similar to 2. 8Ga) TTGs have been discovered in more than 10 areas, whereas Late Neoarchean TTGs almost occur in every Archean area. The common features of the Archean TTGs in the NCC are summarized as follows. 1) > 2. 8Ga TTGs locally occur in the NCC, only accounting for less than 5% of the Archean TTGs in the basement. They do not show an increasing trend in distribution with time, but this may be due to uneven reworking of old rocks during later geological processes. > 2. 6Ga TTGs mainly occur within the three ancient terranes identified by Wan et al. (2015) Neoarhean TTGs widely occur all over the NCC, same as other cratons in showing that the Neoarchean is the most important period of continental growth; 2) 3. 1 similar to 3. 8Ga and 2. 7 similar to 2. 9Ga intrusive rocks mainly are trondhjemite and tonalite, respectively, with some gabbro, diorite and crustally derived granites. Both the trondhjemite and tonalite are important during the period of 2. 5 similar to 2. 6Ga, it is until then that granodiorites widely occur together with K-rich granite (including monzogranite and syenogranite), a result of continental crust becoming high maturity; 3) TTG rocks exhibit variable REE contents from weakly to strongly fractionated REE patterns at similar to 3. 3Ga. This may be a result of thickening of continental crust during that period. 2. 5 similar to 3. 3Ga TTGs show large variations in REE patterns, although many of them have strong REE differentiation patterns, indicating variable forming conditions. Whole-rock Nd isotopes and Hf-in-zircon isotopes indicate that juvenile additions played important roles in formation of TTGs, however, crustal recycling was also necessary to account for the composition features of some TTGs, including 3. 8Ga trondjemitic rocks in the Anben area; 4) Long-term magmatism from 2. 9Ga to 3. 8Ga related to mantle activity and crustal reworking widely occurred in Anben. In eastern Hebei, detrital zircons record almost continuous ages ranging from 3. 4Ga to 3. 88Ga, although only 3. 0 similar to 3. 4Ga rocks were discovered until now. These suggest that mantle underplating or overturn activity may have been the main mechanism of continental growth and reworking before the Mesoarchean in the NCC. In contrast, continental growth was extensive and strong during the Neoarchean period, as suggested by the vast quantity of TTGs, the similar to 2. 5Ga tectono-thermal event was well developed, as recorded by metamorphic and anatectic zircons. These indicate that the continental crust of the NCC became thick enough at that time. It is considered that plate tectonics began to play an important role in the NCC during the Late Neoarchean.
