Late Neoarchean crust-mantle geodynamics: Evidence from Pingquan Complex of the Northern Hebei Province, North China Craton

Abstract

A late Neoarchean intra-oceanic arc along the northwestern margin of Eastern Block (EB), North China Craton, provides important insights into the nature of Archean mantle sources and crust-mantle geodynamics. The Pingquan Complex and the entire Northern Hebei Province (NHB) are located in the middle part of the arc, and overlap the northern extent of the Trans-North China Orogen. Zircon U-Pb isotopic age data reveal that the Pingquan Complex consists of ~2537-2515 Ma dioritic gneisses, ~2506-2503 Ma amphibolites, and ~2491 Ma quartz monzodioritic to monzogranitic gneisses, and they show dominantly positive zircon εHf(t) (-0.6-+5.4) that are lower than coeval model depleted mantle values. Geochemical data for the Pingquan rocks and synchronous metabasalts and granitoid gneisses of Huai'an-Xuanhua and Dantazi complexes in the NHB are integrated. Except for the monzogranitic gneisses that were derived from partial melting of juvenile metagreywackes, the other rocks of the Pingquan Complex were derived from a metasomatized lithospheric mantle, and subjected to variable fractionation of clinopyroxene, hornblende and plagioclase, without significant crustal contamination. Moderately depleted zircon εHf(t), and high Sm/Hf and Nb/Ta (mostly of 1.34-3.96 and 15.50-32.58) suggest that the lithospheric mantle was enriched by subducted pelagic sediments metamorphosed to rutile-bearing eclogites before melting. Late Neoarchean crust-mantle geodynamic processes in the NHB are reconstructed. Intra-oceanic subduction initiated offshore of the northwestern margin of the EB at ~2.55 Ga or earlier. Partial melting of slab basalts occurred at ~2542-2499 Ma, with the melts contaminated by mantle wedge materials forming TTGs. Meanwhile, the sub-arc lithospheric mantle was enriched by fluids and melts released from slab basalts and pelagic sediments, and partial 3 melting of this moderately depleted mantle generated ~2537-2503 Ma diorites and basalts. Following final accretion of the arc onto the continental margin of the EB, the slab rollback/breakoff and asthenospheric mantle upwelling triggered partial melting of the metasomatized lithospheric mantle and crustal anatexis, generating ~2491 Ma quartz monzodioritic and monzogranitic rocks. Accordingly, the NHB records Neoarchean crustal growth linked to oceanic subduction and arc-continent accretion, and highlights the importance of resolving the nature of mantle sources and crust-mantle interactions in understanding Archean crustal growth and evolution.

A Palaeoarchean–Mesoarchean micro-continent entrained in the Jiao-Liao-Ji Belt at the southeastern North China Craton: evidence from the zircon record in the Bengbu area

“…The metamorphic ages of c. 2.5 Ga are consistent with those reported from other Archean basement complexes in the Eastern Block of the NCC (e.g. Zhao et al 1998;Ge et al 2003;Geng et al 2006;Yang et al 2008;Liu et al 2011;Lv et al 2012;Wan et al 2012;Wang et al 2012bWang et al , 2015Wang et al , 2017bWu et al 2013), representing a large-scale end-Neoarchean tectonothermal event related to underplating of large amounts of mantlederived magma in the Eastern Block (Zhao et al 1998;Yang et al 2008;Wu et al 2013;Wang et al 2015). On the other hand, similar late Palaeoproterozoic metamorphic ages have been found in nearly all the major basement lithologies in the study area (Xu et al 2006;Guo & Li, 2009;Liu et al 2009Liu et al , 2017cLiu et al , 2018Wan et al 2010;Fig.…”

Cyclic formation and stabilization of Archean lithosphere by accretionary orogenesis: Constraints from TTG and potassic granitoids, North China Craton

“…Thus, the Northern Liaoning Terrane likely accreted onto the northern continental margin of NCC after ~2530 Ma, marking final stabilization of the regional continental crust (Figure b). Similarly, a late Neoarchean intra‐oceanic arc system was proposed for the region southwest of Northern Liaoning Terrane (Western Liaoning, Zunhua‐Qinglong Block of Eastern Hebei, and Wutai Complex), which accreted onto the >2.7 Ga continental nucleus of Eastern Block at the end of the Archean [ Liu et al ., ; W. Wang et al ., , , , ; Guo et al ., ].…”

“…Similarly, a late Neoarchean intra-oceanic arc system was proposed for the region southwest of Northern Liaoning Terrane (Western Liaoning, Zunhua-Qinglong Block of Eastern Hebei, and Wutai Complex), which accreted onto the >2.7 Ga continental nucleus of Eastern Block at the end of the Archean [Liu et al, 2006;W. Wang et al, , 2015W. Wang et al, , 2017Guo et al, 2013].…”

A Ca. 2.8‐Ga Plume‐Induced Intraoceanic Arc System in the Eastern North China Craton

“…Subsequently, the discoveries of ~3.0–2.8‐Ga eclogite inclusions within kimberlites, together with the rapid decrease in the net rate of crustal growth from ~3.2 to 2.7 Ga, indicated that the worldwide onset of plate tectonics occurred during ~3.2–2.7 Ga, although the mantle plume regime still played an important role locally (Dhuime et al, ; Naeraa et al, ; Rollinson, ; Shirey & Richardson, ; Van Kranendonk, ). Based on detailed investigations of field mapping, petrology, and geochemistry in the past 20 years, an ~2.6–2.5 Ga more than 1,000‐km length NNE‐SSW‐trending intraoceanic arc system has been described in the northwestern margins of the eastern North China Craton (ENCC), indicating that the late Neoarchean geodynamic regime was dominated by plate tectonics (Bai et al, , , ; Fu et al, , ; Guo et al, ; Liu et al, , , , , , , , , ; Liu et al, ; Liu et al, ; Wang, ; Wang et al, ; Wang et al, ; Wang et al, ; Wang et al, ; Yongjun et al, ; Zhang et al, ). What geodynamic processes led to transformation of the Hadean‐Paleoarchean mantle plume regime to the Mesoarchean to Neoarchean major plate tectonic regime and how the Archean subduction zones initiated are still unknown, which presents serious barriers to understanding the geodynamic evolution of the early Earth crust.…”