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• The Lechangxia and Bacun groups in the Cathaysia Block was deposited during Ediacaran and early Cambrian. • These successions formed in passive setting, except for the mid Bacun Group in collisional setting. • A mid Cambrian uplift led to a provenance change from exotic to intrinsic sources in the Cathaysia Block. • The Cathaysia Block was linked to east Gondwana at lease since ca. 630 Ma. Paleogeographic reconstruction of the Cathaysia Block of South China and its link with orogeny associated with Rodinia and Gondwana remain enigmatic, leading to controversial models proposed for supercontinental configuration. This study presents detailed provenance analysis of late Neoproterozoic to early Paleozoic sedimentary successions from the Cathaysia Block, to trace the sedimentary provenance, that was essentially linked to previously adjacent continents/blocks. Zircon U-Pb dating combined with published paleontological evidence suggests an Ediacaran depositional age range (633–542 Ma) for the Lechangxia Group, while deposition of the Bacun Group most likely commenced during early Cambrian. The older strata were sourced mainly from recycling of quartz rich sedimentary rocks while the younger one received sediments dominantly from felsic igneous rocks. High SiO 2 contents (54.6–79.3 wt%) and K 2 O/Na 2 O ratios (0.69–35.7), detrital zircon age distribution and abundant monocrystalline quartz indicate a passive setting for Ediacaran and early Cambrian successions. In great contrast, the middle Cambrian strata was likely deposited in collisional setting, considering relatively lower SiO 2 contents (67.9–74.5 wt%) and K 2 O/Na 2 O ratios (0.97–1.63) plus absence of old zircons. This tectonic transition is consistent with the change from quartz arenite to arkose that could be related to a disconformity between early and middle Cambrian strata. Dominant late Mesoproterozoic detritus (1250–1050 Ma) in the Lechangxia Group was possibly sourced from older Grenville orogens (1300–1050 Ma) in western Australia and East Antarctica because rocks of these ages are rare in the Cathaysia Block. Similarly, abundant early Neoproterozoic clastic (1000–950 Ma) in the late Ediacaran and early Cambrian successions imply an increasing input from younger Grenville orogens (990–950 Ma) in East Antarctica and eastern India. Thus the Cathaysia Block was a part of the East Gondwana assembly and was linked to eastern India, East Antarctica and western Australia during Ediacaran and Cambrian. The source change was coeval with the Pinjarra Orogeny (550–520 Ma) and the early stage of the Kuunga Orogeny (570–550 Ma). In middle Cambrian strata, the middle Neoproterozoic sediments (850–700 Ma) were mainly derived from intrinsic sources, likely to be the Wuyishan terrane. This provenance variation can be linked to the middle Cambrian uplift of the Cathaysia Block in synchronous with the later phase of the Kuunga Orogeny (530–480 Ma). [ABSTRACT FROM AUTHOR]

The geological evolution of the Central African Fold Belt (CAFB) remains debated. The granitoids, orthogneisses and granitic veins from the Goa-Mandja area (Adamawa-Yade domain) are considered to constrain this belt. These rocks are consistent with late-D 2 regional emplacement and synchronous with the magmatism at ~600 Ma within the CAFB in Cameroon and its extension into northeastern Brazil, as the zircon U Pb dating points to 603–598 Ma crystallization ages. Analytical data reveal slightly elevated δ18O zrn (6.45–7.17‰) and δ18O WR (8.20–8.61‰), moderate to high SiO 2 (59.70–77.23 wt%), low MgO (0.07–2.77 wt%), Cr (0.29–55.12 ppm), Ni (0.45–33.6 ppm), V (1.52–116.62 ppm) and Mg# (0.02–0.36) contents, indicating crustal origin. The low to medium 87Sr/86Sr i (0.703328–0.722670) and positive to negative ε Nd(t) (+5.7 to −9.9), coupled with the diversity of Nd model ages (T DM2) support the heterogeneity of crustal protoliths. The high positive ε Nd(t) (+5.7) of the granitic vein indicates derivation from juvenile Neoproterozoic (Nd-T DM2 at 854 Ma) crustal protolith. T DM2(Nd) and T DM2(Hf) ages of 1188–2120 Ma and 2173–2480 Ma also suggest the involvement of Mesoproterozoic to Paleoproterozoic crustal protoliths. Samples show metaluminous to weakly peraluminous, high-K calc-alkaline to shoshonitic and I-type granitoid features and are similar with crustal rocks in regard to LILE (Rb, K) and LREE enrichments and HFSE (Nb, Ta, Ti) depletions. These combined features indicate slab subduction related setting for the magma generation. Slab subduction may have generated the heat necessary to provoke partial melting at the lower crustal level. Considering their position close to the Tchollire-Banyo Fault corridor, at the transition between the Adamawa-Yade and northern domains, the subduction derived features shown by the Goa-Mandja I-type granitoids could be related to the subduction of an old plate boundary during amalgamation of Gondwana. Therefore, the Goa-Mandja area records dominant magmatic accretion along the northern margin of the Congo craton (active margin) associated with a possible northwestern subduction. • The Goa-Mandja granitoids formed at 603–598 Ma. • Variable types of granitoids are identified in the Goa-Mandja area. • They were originated from heterogeneous crustal protoliths. • They are related to the subduction of an old plate boundary during Gondwana assembly. [ABSTRACT FROM AUTHOR]

• The Linte massif reveals a protracted magmatism which lasted at least 60 Ma. • Rocks show geochemical affinities of I-type, shoshonitic and metaluminous granitoids. • The 660 and 630 Ma rocks originate from source involving mantle material which could have been mingled or mixed with crustal component while the 600 Ma rocks come from crustal material. • They were formed during the syn- collisional phase of the Pan-African orogeny. The Central African Fold Belt (CAFB) holds a key position in understanding the process and implications of the Pan-African orogeny in central Africa. However, it has not been fully understood as geological information on some vital domains is not yet available. The Linte massif in the Adamawa-Yade, one of the unrepresented terranes, was investigated and its whole rock geochemical, zircon U-Pb geochronology and Hf-O isotope characteristics and whole rock Sr-Nd data are presented and discussed here. The Linte massif is largely constituted of syenite and subordinate monzonite. The zircon U - Pb dating reveals three major ages at 660, 630 and 600 Ma, indicating a protracted magmatism which lasted at least 60 Ma, during the Neoproterozoic. The rocks are shoshonites, I-type and metaluminous. They have high LILEs (Cs, Rb, Ba and Sr), HFSEs (Th and U) and LREE contents. Their Nb/U, Ta/U, Ce/Pb, Th/La and Th/U ratios, δ18O zrn (5.3–7.6‰) and zircon εHf(t) (−14.7 to +3.2), point toward predominantly crustal with or without a mantle component in the sources. The negative εNd(t) values (−8.1 to −10.0), Paleoproterozoic Nd-T DM model ages (ca. 1700–1900 Ma), Hf-T DM2 ages of ca. 1300–2400 Ma of zircon grains in Neoproterozoic rocks underline their derivation from Mesoproterozoic to Paleoproterozoic basement rocks. The lithospheric mantle-generated heat facilitated partial melting in the sources region, as inferred from the shoshonitic affinity and the subduction-related geochemical features (Nb, Ta and Ti depletion). A mainly crustal source with a minor mantle component is inferred for the 660 Ma magmatism and for the 630 Ma rocks emplaced during crustal thickening. On the other hand, the 600 Ma (youngest) magmatic rocks were derived from a crustal source. We infer a subduction-collision setting for the Linte massif during the 660–600 Ma interval. The 630–600 Ma interval of the culmination of collision is consistent with the timing of the main convergence of the Brasiliano Orogeny recorded in South America (∼630–600 Ma), suggesting continuation of tectonic features into the western Gondwana. [ABSTRACT FROM AUTHOR]

It is debated whether global-scale tectono-magmatic quiescence prevails on the Earth during the early Paleoproterozoic. The early Paleoproterozoic meta-mafic and intermediate rocks in the southwestern Yangtze Block of South China could provide an opportunity to constrain not only the tectonic evolution of the Yangtze Block itself but also augment our understanding of the global tectono-magmatic lull during the early Paleoproterozoic. Zircon U Pb geochronological study indicates that the meta-mafic rocks were emplaced at ca. 2.32 Ga, whereas the intermediate rocks were emplaced at ca. 2.35 Ga. These two lithologies are characterized by subduction-related whole-rock geochemical (such as depleted Nb, Ta and enriched Rb, K, Pb) and unradiogenic Nd Hf isotopic signatures (ε Hf (t) < 0, ε Nd (t) < 0), implying a derivation from a geochemically enriched lithospheric mantle modified by ancient subduction. Thermodynamic modeling further suggests that the intermediate rocks are products of the AFC process between mantle-derived basaltic magma and TTG-like basement rocks at shallow crustal levels. We interpret this as occurring within a post-orogenic extensional setting. Integrated with the published work, we further posit that the Yangtze Block experienced a tectonic regime transition from compressive orogenesis to post-orogenic extension during the early Paleoproterozoic, and the magmatic activities in several crustal blocks are still active until ~2.3 Ga and therefore places important constraints on the beginning of the tectono-magmatic lull. [Display omitted] • 2.35–2.32 Ga mafic-intermediate magmatism is identified in the SW Yangtze Block. • Mafic-intermediate rocks in this study were derived from the lithospheric mantle. • Tectonic transition from orogeny to post-orogenic extension at ~2.35 Ga in Yangtze. [ABSTRACT FROM AUTHOR]