Precambrian Research最新文献

{"title":"Zircon, monazite and titanite U-Pb geochronology revealing Orosirian metamorphic events within the Guiana Shield, Amazonian Craton","authors":"Matheus Scalabrin,&nbsp;Robert de Lima Muniz,&nbsp;Ticiano José Saraiva dos Santos","doi":"10.1016/j.precamres.2025.107766","DOIUrl":"10.1016/j.precamres.2025.107766","url":null,"abstract":"<div><div>Petrography coupled with U-Pb geochronology of migmatites enables the observation of processes and mechanisms involved in continental crust generation and transformation during orogeny. This study focuses on high-grade rocks of four lithostratigraphic units in the Guiana Shield, Amazonian Craton: the Trairão Suite, the Cauarane Group, the Rio Urubu Suite, and the Serra da Prata Suite. Petrographical and geochronological studies of these units reveal that the Orosirian Akawai Orogeny took place from approximately 2.04 to 1.93 Ga. During these 110 million years two high-grade events occurred associated with partial melting and magmatism. Metamorphic event M₁ (2.02 – 1.99 Ga), represented by a grey diatexite of the Trairão Suite, is related to fluid-present partial melting under amphibolite facies conditions. The age of anatexis (2.02 Ma) was obtained for zircon from a dioritic metatexite enclave in the diatexite. The crystallization of the melt generated in this event occurred at 2.00 Ga, obtained for zircon from the grey diatexite. Hornblende-biotite metatexite (Rio Urubu Suite), garnet-sillimanite-K-feldspar metatexite (Cauarane Group), and clinopyroxene-hornblende-orthopyroxene gneiss (Serra da Prata Suite) record the second high-grade metamorphic event M₂ (1.97 – 1.93 Ga). The anatexis of the Cauarane Group occurred by biotite dehydration under high amphibolite to granulite facies conditions. The crystallization of the anatectic melt in the Cauarane Group occurred between ca. 1.96 Ga (metamorphic zircon rims) and 1944 ± 5 Ma (U-Pb monazite). The water-fluxed partial melting in the hornblende-biotite metatexite (Rio Urubu Suite) took place under amphibolite facies conditions, with the crystallization of the anatectic melt occurring at 1938 ± 11 Ma. Granulite facies metamorphism occurred in lenses of clinopyroxene-hornblende-orthopyroxene gneiss of the Serra da Prata Suite at 1949 ± 4 Ma (metamorphic zircon) contemporaneous with dry magma emplacement. Statherian reactivation along NE-SW-trending shear zone in the center of the Guiana Shield was identified in titanite in hornblende-biotite metatexite (Rio Urubu Suite), probably induced by the accretion of the Rio Negro Belt (1.86 – 1.72 Ga).</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107766"},"PeriodicalIF":3.2,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143715277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tectonically-induced neptunian dykes and breccias of the Paleoproterozoic Teena Dolomite: Significance to stratiform zinc deposits in the McArthur Basin, Australia","authors":"Mana Ryuba ,&nbsp;Malcolm W. Wallace ,&nbsp;Ashleigh v.S. Hood ,&nbsp;Christopher P. Reed ,&nbsp;Nicola Cawood","doi":"10.1016/j.precamres.2025.107768","DOIUrl":"10.1016/j.precamres.2025.107768","url":null,"abstract":"<div><div>A widespread system of breccias and neptunian dykes is present within the Paleoproterozoic Teena Dolomite of the McArthur Basin. Most breccia types within the unit are infilled by early fibrous marine cements and dark grey sediments. We interpret the dominant breccia types as <em>in-situ</em> synsedimentary fracture systems (neptunian dykes) while some matrix-supported breccias are likely to be mass flow deposits. Fibrous marine cements filling the neptunian dykes have several different textures and all now consist of dolomite. Petrographic evidence indicates the cements were likely precipitated as calcite and dolomitized during early diagenesis. The trace and rare earth element chemistry of the marine cements is typical of Paleoproterozoic marine cements and indicate relatively anoxic marine conditions.</div><div>The breccias in the Teena Dolomite appear to be the result of a basin-wide tectonic event that occurred during Teena Dolomite to early Barney Creek time at ∼1640 Ma. Early marine-cemented neptunian dykes likely formed by tectonic fracturing and gravitational collapse on tectonic highs. Many large stratiform Zn-Pb deposits in northern Australia (HYC, Teena, Lady Loretta, Mt Isa) are hosted by shales that are coeval with this tectonic event, suggesting a genetic link between tectonism and mineralization. We suggest that this ∼1640 Ma tectonic event is responsible for both the release of mineralization fluids (via faulting and/or dewatering), and the deposition of deeper water organic-rich fine-grained sediments that host the mineralization (via tectonic subsidence). This tectonic event appears to be an important component of the sedimentary exhalative mineral system in the Carpentaria Zinc Belt of northern Australia.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107768"},"PeriodicalIF":3.2,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143697846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial distribution of the lithospheric density structure in three large cratons in China based on GOCE gravity gradient data","authors":"Yu Tian ,&nbsp;Huiyou He ,&nbsp;Lei Shi ,&nbsp;Qing Ye ,&nbsp;Aizhi Guo ,&nbsp;Yong Wang","doi":"10.1016/j.precamres.2025.107771","DOIUrl":"10.1016/j.precamres.2025.107771","url":null,"abstract":"<div><div>The long-term stability of continental cratons can prevent them from being transformed by tectonic processes, such as late-stage plate subduction and convective erosion. This stability is closely related to their unique material composition and lithospheric root structure. The tectonics of China exhibit distinct features compared with those of other regions in the world. Studying the lithospheric density structure of the three large cratons offers an effective approach for understanding the dynamic mechanisms involved in the evolution of China continental cratons. Gravity observations are sensitive to density changes. In this study, after the GOCE satellite gravity gradient data in China and adjacent areas are processed, the methods of boundary identification and depth imaging are combined to effectively obtain the spatial distribution of the lithospheric density structure. The horizontal and vertical distributions of detailed structural lithospheric features in three large cratons in China are obtained. The results indicate that the North China Craton (NCC) has experienced destruction in both the north–south and east–west directions. The boundaries of the suture zone in the southern South China Craton (SCC) are consistent with the structural lines and are more oriented towards the eastern side of the Jiangshan Shaoxing Fault in the eastern SCC. At the southern edge of the Tarim Craton (TC), the features of the spatial distribution of density do not indicate southwards movement of material. With the features of the spatial distribution in three large cratons in China, the features of the distributions in three large cratons are compared, and the reasons for the dynamic mechanism are further analysed and summarized.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107771"},"PeriodicalIF":3.2,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143687705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Early Paleoproterozoic mafic to felsic magmatism from the Cuoke Complex, South China: Implications for the early tectonic evolution of the southwestern Yangtze Craton","authors":"Jibiao Zhang ,&nbsp;Xiaozhong Ding ,&nbsp;Yanxue Liu ,&nbsp;Heng Zhang ,&nbsp;Peiwen Liu ,&nbsp;Chenglong Shi","doi":"10.1016/j.precamres.2025.107769","DOIUrl":"10.1016/j.precamres.2025.107769","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The early Paleoproterozoic architecture and tectonic evolution of the Yangtze Craton in present-day southern China remain poorly understood due to the limited outcrops of rocks from this period. The recently discovered Cuoke Complex in the southwestern Yangtze Craton preserves numerous early Paleoproterozoic igneous rocks, providing a valuable opportunity to investigate the early evolution of the Yangtze Craton. On the basis of lithological features, magmatic zircon U–Pb–Lu–Hf isotopes, and whole-rock geochemical characteristics, four main lithological assemblages have been identified, and their petrogeneses have been revealed. (1) The ca. 2.36 Ga monzogranites have low Zr + Nb + Ce + Y contents (155–267 ppm), high A/CNK ratios (1.14–1.42), and low 10,000*Ga/Al ratios (1.66–2.50), which are typical of S-type granites. These monzogranites display negative whole-rock ε&lt;sub&gt;Nd&lt;/sub&gt;(t) (−4.7 to −7.6) and zircon ε&lt;sub&gt;Hf&lt;/sub&gt;(t) values (−2.4 to −4.8) and high CaO/Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; (0.01–0.08) and CaO/Na&lt;sub&gt;2&lt;/sub&gt;O ratios (0.04–0.32), suggesting that they formed through the remelting of ancient pelites. (2) The ca. 2.33 Ga diorites are characterized by high Sr contents (556–619 ppm), high Sr/Y (63.0–83.1) and (La/Yb)&lt;sub&gt;N&lt;/sub&gt; ratios (24.7–28.1), and low Y (7.45–9.17 ppm) and Yb (0.94–1.11 ppm) contents; thus, these rocks resemble adakites. The elevated Mg&lt;sup&gt;#&lt;/sup&gt; values (46–56), high Cr (106–125 ppm) and Ni (38.9–43.9 ppm) contents, and positive ε&lt;sub&gt;Nd&lt;/sub&gt;(t) (+2.4 to + 4.2) and ε&lt;sub&gt;Hf&lt;/sub&gt;(t) values (+1.4 to + 8.4) indicate that these rocks originated from the partial melting of a subducted oceanic slab. (3) The ca. 2.32 Ga mafic rocks exhibit typical Nb-enriched basaltic features, with high TiO&lt;sub&gt;2&lt;/sub&gt; (2.08–3.94 wt%) and Nb (7.63–16.7 ppm) contents and elevated Nb/Th (4.85–11.7), Nb/La (0.33–0.87), and Nb/U (13.4–32.1) ratios. The rocks have decoupled Nd–Hf isotopes with relatively low whole-rock ε&lt;sub&gt;Nd&lt;/sub&gt;(t) (+2.1 to + 3.6) values and relatively high zircon ε&lt;sub&gt;Hf&lt;/sub&gt;(t) (+2.2 to + 9.0) values, suggesting that they were derived from a mantle wedge modified by slab-derived adakitic melts. (4) The ca. 2.32 Ga granites display high Zr + Nb + Ce + Y contents (451–522 ppm), high 10,000*Ga/Al (2.58–2.69), Y/Nb (1.32–1.94), and Yb/Ta ratios (1.09–1.89), and significantly negative Eu, Ba, Sr, and Ti anomalies, indicating an affinity with A&lt;sub&gt;2&lt;/sub&gt;-type granites. The peraluminous features (A/CNK = 1.05–1.24) and negative whole-rock ε&lt;sub&gt;Nd&lt;/sub&gt;(t) (−2.9 to −5.5) values and zircon ε&lt;sub&gt;Hf&lt;/sub&gt;(t) values (−2.1 to −5.1) suggest that these rocks formed through the partial melting of ancient metasedimentary rocks. Considering previous geochronological and geochemical studies of other ancient complexes within the Yangtze Craton, we propose that the ca. 2.36 Ga monzogranites were most likely generated in a &lt;em&gt;syn&lt;/em&gt;-collisional setting, whereas the ca. 2.34–2.32 Ga adakites, Nb-enriched mafic rocks, and","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107769"},"PeriodicalIF":3.2,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143683741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revisiting the formation ages of Tangjiazhuang Group: Insights from new U-Pb zircon ages in TTG gneisses of the Jiaobei terrane, North China Craton","authors":"Rucheng Zhang ,&nbsp;Lei Zhao ,&nbsp;Mingguo Zhai ,&nbsp;Ross N. Mitchell","doi":"10.1016/j.precamres.2025.107773","DOIUrl":"10.1016/j.precamres.2025.107773","url":null,"abstract":"<div><div>The Jiaobei terrane is a typical and representative early Precambrian terrane of the North China Craton (NCC) characterized by extensively metamorphosed supracrustal rocks. These supracrustal units are of great importance for deciphering the NCC’s tectonic evolution, mineralization processes, and environmental responses during the early Earth. However, the distribution of Archean supracrustal rocks in the Jiaobei terrane is not as extensive as in other parts of the NCC. Despite the most commonly used classification of the Archean supracrustal rocks in the Jiaobei terrane into the Mesoarchean Tangjiazhuang Group and the Neoarchean Jiaodong Group, the precise formation age of the Tangjiazhuang Group has remained elusive. Addressing this gap, this study introduces new zircon U–Pb geochronological insights from TTG (Tonalite-Trondhjemite-Granodiorite) gneisses that intruded the Tangjiazhuang Group. The analyzed zircons predominantly exhibit magmatic cores with metamorphic overgrowth rims, indicative of complex geological processes. Our findings reveal two distinct age groups at 2794 ± 27 Ma and 1914 ± 36 Ma, corresponding to the intrusion of TTG gneisses during the late Mesoarchean and their subsequent metamorphism in the Paleoproterozoic, respectively. They were later intruded by the Paleoproterozoic granitic gneiss at 2194 ± 16 Ma. Combined with field observation and previous studies, the new age data definitively suggest that the Tangjiazhuang Group was formed by at least the late Mesoarchean, thereby offering crucial refinements to the temporal framework for the early crustal formation and evolution of the NCC. The lack of continent-derived components (pelitic rocks) in this lithological unit implies submerged environment for the Mesoarchean Jiaobei terrane of the eastern NCC.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107773"},"PeriodicalIF":3.2,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143687704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Review of Paleoproterozoic tectonics in the southern West African Craton: Insights from multi-disciplinary data integration","authors":"Julien Perret ,&nbsp;Mark W. Jessell ,&nbsp;Quentin Masurel ,&nbsp;Patrick C. Hayman ,&nbsp;Nicolas Thébaud ,&nbsp;Lenka Baratoux ,&nbsp;Alain Kouamélan ,&nbsp;Aurélien Eglinger ,&nbsp;Anne-Sylvie André-Mayer ,&nbsp;Augustin Y. Koffi ,&nbsp;Ibrahima Dia ,&nbsp;Jacques Koné ,&nbsp;James Davis ,&nbsp;Ousmane Wane ,&nbsp;Prince O. Amponsah ,&nbsp;Seta Naba ,&nbsp;Oliver Vanderhaeghe","doi":"10.1016/j.precamres.2025.107707","DOIUrl":"10.1016/j.precamres.2025.107707","url":null,"abstract":"<div><div>For over a century, research has focused on the southern West African Craton (sWAC), aiming to unravel its lithological, geochemical, geochronological, structural, metamorphic, and metallogenic record. Yet, the late Siderian to early Rhyacian (c. 2350–2265 Ma) geodynamic setting of the sWAC remains poorly constrained due to (i) the unresolved configuration of adjacent Archean blocks; (ii) limited geochronological data for the lowermost stratigraphic units; and (iii) extensive overprinting by subsequent magmatic, tectonic, and thermal events. Using a multidisciplinary data integration approach, it is however possible to conduct the analysis of tectonic processes governing the emplacement of the Paleoproterozoic granite-greenstone belts of West Africa.</div><div>In this review, we integrate all available published datasets and knowledge to provide new insights on the late Siderian to Rhyacian tectonic evolution of the sWAC. This data compilation is presented and discussed in the form of key time slices (c. 2350–2265 Ma, 2265–2200 Ma, 2200–2135 Ma, 2135–2120 Ma, 2120–2095 Ma and 2095–2060 Ma), which mark evolutionary stages in the geological history of the region. The results of our analysis support the shift from enigmatic Archean tectonic modes to plate tectonics, with the onset of subduction at c. 2265 Ma.</div><div>However, critical knowledge gaps remain, particularly regarding the tectonic significance of greenstone belts and the role of the West African Craton in potential configurations of the Eburnean–Transamazonian Orogen during the assembly of Nuna. To address these issues, future research directions are proposed to conclude this synthesis.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107707"},"PeriodicalIF":3.2,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143683740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"TTG petrogenesis and U–Pb SHRIMP zircon geochronology constraints on the tectonic regime and formation of the Mesoarchean crust from the Ourilândia–Tucumã area in the Carajás Province, Amazonian Craton, Brazil","authors":"Yury Harrison da Costa Reis ,&nbsp;Davis Carvalho de Oliveira ,&nbsp;Luana Camile Silva-Silva ,&nbsp;Williamy Queiroz Felix ,&nbsp;Bhrenno Marangoanha ,&nbsp;Marco Antônio Galarza ,&nbsp;José de Arimatéia Costa de Almeida","doi":"10.1016/j.precamres.2025.107767","DOIUrl":"10.1016/j.precamres.2025.107767","url":null,"abstract":"<div><div>Tonalite–trondhjemite–granodiorite (TTG) magmatism marked crucial episodes in early crustal growth and cratonization worldwide; petrogenetic processes, tectonic configurations, and sources of TTGs are the focus of continuous debate. Here, we present a geochemical and geochronological (zircon U–Pb SHRIMP) study of TTG granitoids to determine their petrogenesis and to better constrain the crustal evolution of Carajás Province. New evidence of preserved TTG crust in the Ourilândia–Tucumã area, which is composed of tonalite–trondhjemites, is presented. The tonalite has an emplacement age of 3.0 Ga. These rocks are consistent with low- and medium- to high-pressure TTGs. Our modeling of the sources that gave rise to these TTGs revealed that the origin of the trondhjemites was related to the 13 % partial melting of an amphibolite/eclogite source at high pressure (approximately 1.5 GPa) in the garnet/rutile stability zone. The tonalite data also suggest 16–22 % partial melting of a metabasaltic crust at medium–low pressures (approximately 1.0 GPa), with little or no influence from garnet in the residue. The source had an affinity with the metabasalts in the greenstone belt sequence of the Tucumã–Gradaús Group. The proposed geodynamic setting of the Carajás Province TTG crust evolved from stagnant lid tectonics to mobile lid tectonics. Drip tectonics occurred over 30–50 Ma, aborted low-angle subduction began to occur, and as the crust became thicker and more resistant, increasingly steep subduction occurred.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107767"},"PeriodicalIF":3.2,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143683742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"P-T path of staurolite-bearing metapelitic schist from the Taihua Complex, southern Trans-North China Orogen, and tectonic implications","authors":"Xinyue Han ,&nbsp;Laixi Tong ,&nbsp;Zhao Liu ,&nbsp;Chao Li ,&nbsp;Mingguo Zhai ,&nbsp;Jiali You ,&nbsp;Feng Zhou ,&nbsp;Kexin Wu ,&nbsp;Xiaoping Long ,&nbsp;Yue Gao","doi":"10.1016/j.precamres.2025.107754","DOIUrl":"10.1016/j.precamres.2025.107754","url":null,"abstract":"<div><div>The Taihua Complex, located on the southern margin of the Trans-North China Orogen (TNCO), North China Craton, is a critical region for decoding tectonic evolution of the TNCO. In this study, an integrated investigation of petrology, phase equilibrium modelling and LA-ICP-MS zircon U-Pb dating is undertaken for the staurolite-bearing metapelitic schist in the Lushan Taihua Complex. Petrographic observations reveal a four-stage metamorphic evolution, including: (1) A pre-peak (M1) assemblage consisting of the garnet core and its mineral inclusions of staurolite, plagioclase, biotite, quartz, ilmenite and rutile; (2) The pressure peak (M2) assemblage represented by the inclusions of plagioclase, biotite, quartz, ilmenite and rutile within garnet rims, and the presence of kyanite pseudomorphs after sillimanite, which is confirmed by the Raman spectra; (3) The decompression stage (M3) characterized by the transformation from kyanite to sillimanite as well as partial replacement of rutile by ilmenite; and (4) the final stage (M4) marked by the fine-grained assemblage of biotite + plagioclase + quartz ± sillimanite, locally surrounding the garnet porphyroblasts. Phase equilibrium modelling results suggest that the metapelitic schist experienced the high-amphibolite facies metamorphism, with <em>P-T</em> conditions approaching 654 ∼ 661℃/8.7 ∼ 9.1kbar (M1) and 751 ∼ 766 ℃/10.7 ∼ 11.1 kbar (M2), followed by a decompression with minor heating to 778 ∼ 795 ℃/7.2 ∼ 7.9 kbar (M3), and finally, the rocks underwent a cooling process until 699 ∼ 702 ℃/7.1 ∼ 7.2 kbar (M4). Thus, a clockwise <em>P-T</em> path is retrieved. Zircon U-Pb dating yields a weighted mean ²⁰⁷Pb/²⁰⁶Pb age of 1883 ± 9 Ma, interpreted as the time of the post-peak cooling. Therefore, it can be inferred that the Taihua Complex has been involved in the collision between the Western and Eastern Blocks of the NCC in the late Paleoproterozoic. Based on previously published data, we propose that the Taihua Complex records the pressure peak metamorphic ages of ca. 1.95 Ga and cooling ages of ca. 1.93(1.92) ∼ 1.80 Ga. The main crustal thickening process possibly occurs at ca. 1.95 Ga, followed by uplifting, and final cooling from ca. 1.93(1.92) − 1.80 Ga.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"421 ","pages":"Article 107754"},"PeriodicalIF":3.2,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The helically coiled microfossil Obruchevella from the upper Ediacaran Miaohe Member in South China","authors":"Qin Ye ,&nbsp;Zhihui An ,&nbsp;Shuhai Xiao ,&nbsp;Sishuo Chen ,&nbsp;Xinghua Chen ,&nbsp;Mingxin Liu","doi":"10.1016/j.precamres.2025.107764","DOIUrl":"10.1016/j.precamres.2025.107764","url":null,"abstract":"<div><div>Exceptionally preserved fossils from Precambrian strata are crucial for our understanding of the origin and evolution of early life on Earth. Some of them (e.g., <em>Obruchevella</em>) are comparable with extant forms in cellular morphology, indicating remarkable evolutionary conservatism or morphological convergence. Here we describe abundant and exceptionally preserved specimens of <em>Obruchevella</em> from the upper Ediacaran Miaohe Member in South China. The new specimens are characterized with a helical filament, a diagnostic feature of the genus <em>Obruchevella</em>, but many of them also have an elongate, axially arranged, rod structure. The axial rod is probably a taphonomic artifact, although we also consider its possible biological origin. Should the axial rod be proven as biological in origin, it may represent a previously undocumented component of <em>Obruchevella</em>, or an organism distinct from but symbiotically associated with <em>Obruchevella</em>. These uncertainties highlight the challenges in distinguishing taphonomic and biological structures in Precambrian microfossils despite their exceptional preservation. Regardless, the new microfossils provide new taphonomic and morphological insights into <em>Obruchevella</em>, which is considered as a morphological analog of the modern cyanobacteria <em>Spirulina</em> and <em>Arthrospira</em>. They also enrich the microfossil diversity of the Miaohe Member, which is better known for macroscopic carbonaceous compression fossils.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"421 ","pages":"Article 107764"},"PeriodicalIF":3.2,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143628993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Archean to early Mesoproterozoic crustal evolution of the Yangtze Craton: Insights from U-Pb-Hf-O isotopic and trace elemental compositions of detrital zircon","authors":"Xinyu Cai ,&nbsp;Rui Li ,&nbsp;Guangyan Zhou ,&nbsp;Heng Luo ,&nbsp;Zhifu Liu ,&nbsp;Nimat Ullah Khattak ,&nbsp;Wei Wang","doi":"10.1016/j.precamres.2025.107751","DOIUrl":"10.1016/j.precamres.2025.107751","url":null,"abstract":"<div><div>Detrital zircons from ancient sedimentary rocks provide essential evidence for deciphering the early crustal evolution of Earth, particularly in ancient cratons with limited ancient rock records. The Yangtze Craton in South China has limited exposure of Archean-Paleoproterozoic rocks, while abundant Paleo-Mesoproterozoic sedimentary units in the southwestern Yangtze Craton contains voluminous Archean detrital zircons. In this study, new U-Pb-Hf-O isotopic and trace elements data of detrital zircons and whole-rock elemental data from the Dongchuan and Hekou Groups are conducted. Three distinct detrital zircon age populations at 2.85 ∼ 2.6 Ga, 2.45 ∼ 2.2 Ga, and 2.0 ∼ 1.75 Ga are identified. Almost all zircons exhibit depleted LREEs, enriched HREEs, pronounced negative Eu anomalies, and positive Ce anomalies, suggesting a magmatic origin. The comparison of U-Pb-Hf isotopic data of detrital zircons with magmatic zircons within the Yangtze basement rocks, coupled with the angular morphology of the zircons, collectively suggest that the provenance originates within the Yangtze Craton rather than exotic terranes. At ca. 2.85 Ga and 2.1 Ga, mean δ¹⁸O values of detrital zircons are 5.8 ‰ and 5.5 ‰, respectively, with corresponding median ε_Hf(t) values of + 4.16 and −0.59. Subsequently, the δ¹⁸O values began to increase markedly, whereas ε_Hf(t) values declined during the same interval. Zircon trace element signatures point to their origin in S-type granites linked to orogenic events, with zircon Eu anomalies indicating crustal thickening at 2.85 Ga and 2.1 Ga, which coincides with the evolutionary trends observed in zircon O-Hf isotopes and resonates with supercontinent cycles. Crust growth curve calculations reveal that the growth of continent nuclei in Yangtze Craton can be tracked back to the late Hadean, reaching nearly 80 % of its present volume during the Meso-Neoarchean, with a subsequent decrease in growth rates. This growth pattern aligns with evolution trends of global crust growth curve, indicating a gradual growth and stabilization of continental crust during the Archean period.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"421 ","pages":"Article 107751"},"PeriodicalIF":3.2,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}