Precambrian Research最新文献

{"title":"2.08 Ga andesitic gneisses in the southwestern Yangtze Block: Unveiling new insights into its geological evolution","authors":"Jun-Ping Liu ,&nbsp;Zai-Bo Sun ,&nbsp;Wei-Ke Li ,&nbsp;Hua-Li Luo ,&nbsp;Shi-Jun He ,&nbsp;Shao-Bin Hu ,&nbsp;Jiang-Tai Zhao ,&nbsp;Hai-bao Yan ,&nbsp;Ming-Guo Zhai ,&nbsp;Hai-Long He","doi":"10.1016/j.precamres.2024.107639","DOIUrl":"10.1016/j.precamres.2024.107639","url":null,"abstract":"<div><div>The early geological history of the Yangtze Block has been difficult to unravel due to limited exposure of Archean to Paleoproterozoic rocks. Through detailed geological investigations and mapping in the southwestern (SW) Yangtze Block, this study identified Paleoproterozoic andesitic and granitic gneisses, as well as associated sedimentary rocks, within the Xinanchang (XAC) Complex. Zircon U-Pb dating yields a concordant age of 2078 ± 11 Ma for the andesitic gneiss, and a weighted mean ²⁰⁷Pb/²⁰⁶Pb age of 1835 ± 12 Ma for the granitic gneiss. The zircon grains from these gneisses exhibit oscillatory zoning and Th/U ratios of 0.40–0.94, corroborating their magmatic origins. Additionally, U-Pb age spectra of concordant zircon grains from the XAC strata range from 1.80 to 2.69 Ga. Together with the intrusive relationship between the 1.84 Ga granitic gneiss and the strata, this implies a depositional age of ca. 1.84 Ga for the XAC strata. The andesitic gneiss exhibits enrichment in large-ion lithophile elements (LILEs) and light rare earth elements (LREEs), but shows depletion in Nb, Ta, and Ti. These geochemical signatures are consistent with those of contemporaneous andesitic magmatic rocks in the northern Yangtze Block, suggesting that they were derived from subduction-related sources. In contrast, the granitic gneiss in the XAC Complex shows A-type granite affinities, similar to contemporaneous granitoids widely found across the Yangtze Block. This indicates that these granitoids were formed in a post-orogenic extensional tectonic setting. The northern and SW Yangtze blocks both show records of a transition from subduction to post-orogenic extensional environments between 2.10 Ga and 1.85 Ga, suggesting that the proto-Yangtze Block likely aggregated before 2.10 Ga.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"417 ","pages":"Article 107639"},"PeriodicalIF":3.2,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142758965","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 Ediacaran Xueqiong ophiolite in the East Kunlun Orogen, northern Tibetan Plateau: Insights into the early evolution of the Proto-Tethys Ocean","authors":"Qingxing Luo ,&nbsp;Bo Hui ,&nbsp;Yunpeng Dong ,&nbsp;Dengfeng He ,&nbsp;Shengsi Sun ,&nbsp;Yuangang Yue ,&nbsp;Xiang Ren ,&nbsp;Bin Zhang ,&nbsp;Rutao Zang ,&nbsp;Yongcheng Li","doi":"10.1016/j.precamres.2024.107638","DOIUrl":"10.1016/j.precamres.2024.107638","url":null,"abstract":"<div><div>Reshaping the tectonic evolution of the Proto-Tethys Ocean is of paramount significance for comprehending the ocean-continent transitions since the Neoproterozoic. Nevertheless, the intricacies of this evolution, particularly during its early stage, remain a pivotal issue that needs further deciphering. The discovery of early Ediacaran ophiolites within the East Kunlun Orogen offers a crucial clue for exploring this issue. This study presents intergrade field geology, zircon U–Pb geochronology and whole-rock geochemistry on the related rocks from this specific ophiolite identified in the Xueqiong area, easternmost East Kunlun Orogen. Field investigations reveal the currently remaining dismembered Xueqiong ophiolite merely include gabbro, basalt and chert, which are in the form of tectonic blocks within an ophiolitic mélange. Zircon U–Pb dating results show that the gabbro samples from two near rock slices yield consistent weighted mean ages of 597 ± 5 Ma and 601 ± 2 Ma, whereas the basalt sample gives a similar age of 600 ± 6 Ma as well, indicating the magmatic component of the ophiolitic suite was formed at ca. 600 Ma during the early Ediacaran. Geochemical analysis indicates that all the gabbro and basalt share a common parental magma. Patterns of rare earth and trace elements show their properties between the enriched mid-ocean ridge basalt and oceanic island basalt models, along with their characteristic trace element covariances aligning with enriched mid-ocean ridge basalt, suggesting a mantle source similar to the enriched mid-ocean ridge basalt, with interaction with the residual asthenosphere mantle material. Relatively low SiO₂, TFe₂O₃ and MnO₂ contents and flat rare earth element patterns of chert, suggesting its lithogenic property and restricted basin setting near the continental margin. These findings collectively indicate that the Xueqiong ophiolite represents remnants of the oceanic lithosphere and overlying deep-sea sediments from the early-stage evolution of the Proto-Tethys Ocean, when the ocean evolution might not have been fully mature and oceanic floor sedimentation capable of receiving terrigenous detritus. This evidence further supports that the Proto-Tethys Ocean in the East Kunlun domain could be traced back at least to the early Ediacaran.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"417 ","pages":"Article 107638"},"PeriodicalIF":3.2,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142758966","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":"Age and composition of the lithospheric mantle beneath Jiande, Zhejiang Province: Implications for crust-mantle co-evolution of the South China Block","authors":"Danni Li ,&nbsp;Yong Xu ,&nbsp;Yantao Hao ,&nbsp;Xue Xiao ,&nbsp;Bin Qin ,&nbsp;Jingao Liu","doi":"10.1016/j.precamres.2024.107637","DOIUrl":"10.1016/j.precamres.2024.107637","url":null,"abstract":"<div><div>Fresh mantle peridotite xenoliths entrained in the Eocene Jiande alkaline basalts from western Zhejiang Province, South China Block (SCB), offer an opportunity to elucidate the compositional and temporal relationships between the subcontinental lithospheric mantle (SCLM) and its overlying crust. The Jiande peridotites (20 lherzolites + one harzburgite) exhibit tightly correlated and relatively fertile whole-rock major element compositions (WR Mg#=89.0–90.8), indicating mild to moderate degrees (mostly ≤ 10 %) of mantle partial melting and limited metasomatism experienced by the Jiande SCLM. The above mantle processes are further underscored by: 1) the nearly unfractionated highly-siderophile-element (HSE) relative abundances ((Pd/Ir)_N = 0.81–1.37, normalized to primitive-upper-mantle values); 2) the robust positive correlations observed between ¹⁸⁷Os/¹⁸⁸Os (0.1196–0.1283) and ¹⁸⁷Re/¹⁸⁸Os ratios (0.112–0.451; R² = 0.79), and Al₂O₃ contents (1.5–3.8 wt%; R² = 0.85) across the majority of high-¹⁸⁷Os/¹⁸⁸Os samples. Both Re-Os (initial ¹⁸⁷Os/¹⁸⁸Os = 0.1172) and Al-Os isochrons (initial ¹⁸⁷Os/¹⁸⁸Os = 0.1181) also yield an age of ∼ 1.4 Ga for the predominant melt depletion event that shaped the formation of the Jiande SCLM, aligning well with the peak of two-stage depleted mantle Hf model ages of the SCB crustal rocks. This age-coupled crust-mantle differentiation event occurring in the Mesoproterozoic may have been controlled by tectonic-magmatic processes during the breakup of the Columbia supercontinent. In addition, two low-¹⁸⁷Os/¹⁸⁸Os (0.1108–0.1128) samples with ∼ 15–20 % melting degrees ((Pd/Ir)_N = 0.15–0.30) show the oldest Re-depleted Os model ages (2.2 and 2.4 Ga) among all the reported SCB mantle peridotites. These older SCLM materials may represent remnants linked to earlier crust-forming events that were incompletely reworked or replaced. Alternatively, they could represent mantle heterogeneity inherited by the newly formed lithospheric mantle during the Mesoproterozoic era.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"417 ","pages":"Article 107637"},"PeriodicalIF":3.2,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142758955","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":"Preservation of igneous and metamorphic charnockites in the Paleoproterozoic Prøven Igneous Complex, Rinkian Orogen, central West Greenland","authors":"A. Dziggel ,&nbsp;L. Bramm ,&nbsp;T.F. Kokfelt ,&nbsp;J. Grocott ,&nbsp;J.F.A. Diener","doi":"10.1016/j.precamres.2024.107634","DOIUrl":"10.1016/j.precamres.2024.107634","url":null,"abstract":"<div><div>The Paleoproterozoic Prøven Igneous Complex (PIC) of the Rinkian Orogen in central West Greenland comprises a suite of arc-related charnockite plutons, extending over an area of at least 7200 km². The PIC was emplaced into paragneisses of the Karrat Group during a series of magmatic events between c. 1900 and 1850 Ma. Magmatism was accompanied by high-grade metamorphism and deformation, culminating in granulite facies peak conditions and partial melting at c. 1820 Ma. To unravel the conditions of charnockite formation and granulite facies metamorphism, a detailed petrographic study was carried out on samples from the PIC and the surrounding paragneisses. The rock types studied include i) charnockites from the massive PIC, ii) charnockites and migmatites from the layered lower PIC, iii) migmatites from the surrounding paragneisses, and iv) igneous enclaves from the lower PIC. Charnockites from the massive PIC generally show a magmatic, porphyritic texture and only minor macro-textural evidence of deformation. The lower PIC and paragneisses are both migmatized and exhibit extensive recrystallization with a solid-state crystal-plastic fabric. Igneous enclaves are found within the lower PIC and show an equigranular, igneous texture. Based on the dominant igneous texture it is interpreted that the massive PIC crystallized from a dry magma and was not significantly overprinted during peak metamorphism. Phase equilibrium modelling, Hb-Pl thermometry and Al-in-hornblende barometry constrain the PIC to have been emplaced at 680–795 °C and 4.2–5.4 kbar. By contrast, the lower PIC and paragneiss samples record granulite facies peak conditions of 785–805 °C and 3.4–4.0 kbar, suggesting that both charnockite magmatism and metamorphism took place at relatively shallow crustal levels. Our results are consistent with the P-T conditions recorded by the 1890–1880 Ma Qikiqtarjuaq Plutonic Suite, an arc-type charnockite intrusion on Baffin Island, Canada. A correlation between the tectonothermal events on Baffin Island and in the Rinkian Orogen is proposed, therefore relating the intrusion of the PIC to the collision of the Meta Incognita microcontinent and the Rae Craton.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"417 ","pages":"Article 107634"},"PeriodicalIF":3.2,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745601","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":"The Neoarchean granitoids in the Yanlingguan area, western Shandong, North China Craton record the transition from TTG to K-rich granitoids","authors":"Yuqing Wang ,&nbsp;Chunyan Dong ,&nbsp;Simon A. Wilde ,&nbsp;Hangqiang Xie ,&nbsp;Shoujie Liu ,&nbsp;Dunyi Liu ,&nbsp;Yusheng Wan","doi":"10.1016/j.precamres.2024.107633","DOIUrl":"10.1016/j.precamres.2024.107633","url":null,"abstract":"<div><div>The Neoarchean is an important period of continental crustal growth worldwide. Determining how the continental crust increases in size and was finally cratonized at the end of the Archean is therefore an important scientific issue in geology. This study involved field investigations, SHRIMP U-Pb zircon dating, zircon <em>in situ</em> Hf isotopic analysis, and whole-rock geochemistry of Neoarchean granitoids at Yanlingguan, a typical Neoarchean area in the western Shandong granite-greenstone belt, North China Craton. Three samples of diorite/TTG that occur as enclaves in monzogranite record the oldest magmatic zircon ²⁰⁷Pb/²⁰⁶Pb ages of 2738–2731 Ma. They have low ΣREE (total REE) contents (37.5–72.4 ppm), low (La/Yb)_n (8.9–25.5) and variable Eu/Eu* (0.90–1.86). The Xinfushan trondhjemite has a weighted mean ²⁰⁷Pb/²⁰⁶Pb age of 2599 ± 4 Ma for magmatic concordant or near-concordant zircons from six samples. The trondhjemites have large REE variations, with ΣREE, (La/Yb)_n, and Eu/Eu* being 36.3–150.9 ppm, 23.9–91.1 and 0.57–2.00, respectively. The Lianhuashan monzogranite has a weighted mean ²⁰⁷Pb/²⁰⁶Pb age of 2502 ± 6 Ma for magmatic concordant or near-concordant zircons from four samples. These rocks have ΣREE contents, (La/Yb)_n and Eu/Eu* of 42.9–573.7 ppm, 2.4–89.1 and 0.31–1.20, respectively. The geochemisal data indicate that the 2.7 Ga diorite/TTG rocks formed by fractional crystallization of mafic magma under low-pressure conditions. In contrast, the 2.6 Ga trondhjemites were most likely formed by a mixture of magmas derived from partial melting of low-K mafic and the earlier tonalitic rocks; whereas the 2.5 Ga monzogranites were derived by partial melting of the earlier TTG rocks, with addition of some sedimentary material. These events commenced with the subduction and melting of early Neoarchean oceanic crust, likely influenced by mantle plume activity, through an increase in crustal melting and consequent increase in the K₂O/Na₂O ratio in the 2.6 Ga TTG, and culminated in the production of the widespread generation of K-rich monzogranites at 2.5 Ga. Western Shandong thus underwent an increase in crustal maturity as it transitioned from TTG-dominated magmatism to K-rich granite, marking cratonization of the North China Craton at the end of the Neoarchean.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"417 ","pages":"Article 107633"},"PeriodicalIF":3.2,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757695","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":"Petrogenesis of the > 2.90 Ga komatiite in the Sujiagou region of the North China Craton: Implications for Archean mantle source and geodynamic setting","authors":"Rui Zuo ,&nbsp;Xiaoping Long ,&nbsp;Bin Wu ,&nbsp;Mei-Fu Zhou","doi":"10.1016/j.precamres.2024.107632","DOIUrl":"10.1016/j.precamres.2024.107632","url":null,"abstract":"<div><div>Komatiite, characterized by high MgO content and low H₂O concentration, is crucial to understanding the Archean magma processes and crust–mantle differentiation. Although well preserved in most cratons, Archean komatiites are scarce in the North China Craton (NCC). The Sujiagou komatiites, as the most typical Archean komatiites in China, were exposed in the Luxi terrane, but their geochronology and petrogenesis types remain controversial. In this study, our new Re–Os data indicate the Sujiagou komatiites originated before 2.90 Ga. The felsic zircons discovered in the komatiites, coupled with Nb–Th–La simulation, suggest ∼ 2 % crustal contamination of the komatiites. Thus, the least-altered, spinifex- and massive-texture samples that underwent unconspicuous crustal contamination were selected as proximate proxies for the primary magma composition. The Al/Ti ratios of the Sujiagou komatiites are comparable to or slightly exceed those of chondrite, suggesting they were aluminium-undepleted komatiites and formed at ∼ 8 GPa. The primitive mantle-normalized rare earth element (REE) patterns show depleted light REE and flat heavy REE, suggesting approximately 50 % partial melting based on REE simulation. Additionally, the komatiites exhibit slightly depleted Os isotope ratios, with an average γ_Os(t) value of -0.3, indicating the magma source is comparable to or slightly depleted to chondrite. Simulation of the relevant Nb/Zr and La/Sm_PM ratios further suggests the mantle source became slightly depleted due to ca. 1 % melt extraction. Furthermore, the Mg isotopic composition of the Sujiagou komatiites (δ²⁶Mg = -0.23 ± 0.03 ‰) is consistent with that of the primitive mantle, indicating the absence of recycled carbonate material in the mantle source. Both Re–Os and Mg isotopes reveal limited involvement of crustal or carbonate material in the mantle source, implying the absence of oceanic slab subduction in the Luxi terrane during this time. The formation of the Sujiagou komatiites can be attributed to a hot mantle plume, resulting from high potential and eruption temperature. The identification of felsic zircons in the Sujiagou komatiites indicates the presence of an ancient continental nucleus in the Luxi terrane. Combined with the spatially adjacent terrigenous clastic sedimentary rocks, we suggest that the Sujiagou komatiites erupted most likely in a continental margin of the old terrane.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"417 ","pages":"Article 107632"},"PeriodicalIF":3.2,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745602","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":"Middle Neoproterozoic (ca. 715 Ma) slab window along the Yangtze northern margin: Constrained from meta-mafic igneous records","authors":"Feifei Zhang ,&nbsp;Mingxia Wang ,&nbsp;Peter A. Cawood ,&nbsp;Yunpeng Dong ,&nbsp;Yifan Wang ,&nbsp;Bo Hui ,&nbsp;Shuai He ,&nbsp;Hongsen Gao","doi":"10.1016/j.precamres.2024.107630","DOIUrl":"10.1016/j.precamres.2024.107630","url":null,"abstract":"<div><div>We constrain the Neoproterozoic tectonic pattern and subduction termination records of the Yangtze Block through new geochronological, geochemical and Sr-Nd-Pb-Hf isotopic data for the metabasites of the Wudang Group in the South Qinling Belt. Our data show that these <em>meta</em>-igneous rocks formed at ca. 715 Ma and can be compositionally classified into five groups: arc- and MORB-like, high-Nb and Nb-enriched metabasite, and high-Mg andesite. Their ε_Nd(t) values range from + 5.4 to −0.4, (²⁰⁶Pb/²⁰⁴Pb)_i from 16.53 to 17.47, (²⁰⁷Pb/²⁰⁴Pb)_i from 15.34 to 15.49, (²⁰⁸Pb/²⁰⁴Pb)_i from 36.54 to 37.46 with Δ8/4 = +65 ∼ +173 and Δ 7/4 = +4.5 ∼ +10.5, respectively. Their source was the convergent plate margin mantle wedge, modified by subduction-related component or interacting with the OIB-type asthenospheric mantle. Together with available data, the Wudang Group in the South Qinling Belt is characterized by the Neoproterozoic volcano-sedimentary rocks, with the volcanic rocks are dominated by the ca. 850–780 Ma mafic, ca. 780–730 Ma felsic and ca. 720–710 Ma mafic rocks. The Wudang Group is overlain by the ca. 700–630 Ma rift-related Yaolinghe Group with the intervening angular unconformity constrained to an age of ca. 710–700 Ma. Based on regional data from the northern margin of the Yangtze Block, we propose a long-lived Neoproterozoic (∼890–710 Ma) a north facing arc-trench system with south-directed subduction ongoing until ca. 710 Ma. This subduction termination could reflect the development of a tear-induced slab window model in the South Qinling Belt.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"416 ","pages":"Article 107630"},"PeriodicalIF":3.2,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705675","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":"Structural evolution of the resource-rich Proterozoic western greater McArthur Basin: A focus on the Daly Waters Fault Zone, northern Australia","authors":"Johann Soares ,&nbsp;Rosalind King ,&nbsp;Simon Holford ,&nbsp;Alan S. Collins","doi":"10.1016/j.precamres.2024.107616","DOIUrl":"10.1016/j.precamres.2024.107616","url":null,"abstract":"<div><div>Proterozoic basins cover vast cratonic areas on every continent. Their basin architecture preserves considerable information that can unravel the tectonic evolution of large parts of the world, yet many do not yet have the resolution of seismic data across them to reveal their internal structure. The ca. 1820–1320 Ma greater McArthur Basin, in the North Australian Craton, is a data-rich exception. Surface exposures in the west (Birrindudu Basin), south (Tomkinson Province) and north (McArthur Basin <em>sensu stricto</em>) are linked together in seismic profiles through the Beetaloo Sub-basin that allow the full basin evolution to be determined.</div><div>A key feature of the basin is the Daly Waters Fault Zone, a north–south-oriented structural formation about 200 km in length. This fault zone serves as a boundary, dividing the Birrindudu Basin and the western Beetaloo Sub-basin from the eastern Beetaloo Sub-basin. It is a complex fault zone with multiple phases of structural extension and compression that have influenced the greater McArthur Basin fill from the Redbank Package (ca. 1820–1700 Ma) to the Wilton Package (ca. 1500–1320 Ma).</div><div>Two dimensional seismic lines and 17 well penetrations in an area encompassing the Birrindudu Basin to the western portion of the Beetaloo Sub-basin and across the Daly Waters Fault Zone are re-interpreted to better understand the evolution of the basin and the role of the Daly Waters Fault Zone. We reveal at least five tectonic events that controlled deposition and exhumation in the region: 1) Extension during the early Redbank Package (ca. 1820–1750 Ma), followed by compression that inverted the Redbank Package (ca. 1740–1700 Ma). 2) Extension during the Glyde Package (ca. 1660–1620 Ma). 3) Compression after deposition of the Glyde Package (ca. 1620–1520 Ma). 4) Extension during the lower Wilton Package (ca. 1500–1400 Ma), and 5) compression after deposition of the Wilton Package (after ca. 1320 Ma).</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"416 ","pages":"Article 107616"},"PeriodicalIF":3.2,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705676","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":"Greenstone belt-hosted Mesoarchaean Mbarga BIF prospect, NW Congo Craton (southern Cameroon): Petrography, geochemistry, Sr-Nd isotopes, zircon u-pb geochronology, petrogenetic, and tectonic implications","authors":"George Lemewihbwen Ngiamte ,&nbsp;Roland Maas ,&nbsp;Eleanor C.R. Green ,&nbsp;Olugbenga Akindeji Okunlola ,&nbsp;Cheo Emmanuel Suh ,&nbsp;Alan Greig ,&nbsp;Ashleigh van Smeerdijk Hood ,&nbsp;Nowel Yinkfu Njamnsi ,&nbsp;Cyril Samndong Tufoin","doi":"10.1016/j.precamres.2024.107631","DOIUrl":"10.1016/j.precamres.2024.107631","url":null,"abstract":"<div><div>Banded Iron Formations (BIFs) interbedded with schists characterize the Mbarga prospect in the Ntem Complex at the northwest edge of the Congo Craton. This study presents new whole-rock geochemical, Sr-Nd, and zircon U-Pb isotopic data for the BIFs and schists to constrain the timing and geodynamic setting of the deposit. The abundances of SiO₂ (52.81 to 79.14 wt%) and Na₂O+K₂O (4.24 to 8.54 wt%) in the schists indicate andesitic, dacitic, to rhyolitic protoliths. Trace element signatures, such as high Ba and depleted Nb-Ta concentrations, suggest a volcanic arc affinity. A well-defined U-Pb zircon age of 2890 ± 4 Ma implies a Mesoarchaean protolith age, while an imprecise Rb-Sr whole-rock age of ca. 2.65 Ga is consistent with known tectonothermal events (∼2.75 and 2.65 Ga) in the Ntem Complex. Initial ε_Nd(2.89) values of + 0.8 to + 2.0 for the schists indicate an unevolved, mantle-like source for the protoliths. The BIFs show partial to extensive alterations of magnetite to hematite-martite and are of the Algoma type. They are characterized by high Fe₂O₃ (∼54.06 wt%) and SiO₂ (∼45.40 wt%) but low Al₂O₃ (∼0.14 wt%), TiO₂ (∼0.1 wt%), Zr (∼4.92 ppm), Th (∼0.11 ppm), and REE-Y contents. Rare earth patterns marked by LREE depletion, positive Eu anomalies (∼2), mild Ce depletion (Ce/Ce* 0.67 to 1.16), and super-chondritic Y/Ho ratios (∼34) suggest formation under anoxic to suboxic Archaean marine conditions, possibly involving mixing of Archaean seawater with minor (0.1–1 %) contributions from medium- to high-<em>T</em> hydrothermal fluids. Sparse 2951 ± 24 Ma zircons, presumably of detrital origin, establish a depositional link to the associated schists, redefining the age of BIF deposition within the Ntem Complex to ca. 2.95–2.89 Ga. However, whole-rock Sm-Nd isotope data for five BIF samples define a scattered array with an imprecise slope equivalent to an age near 1004 ± 78 Ma, which may reflect a previously unrecognized recrystallization event in the BIFs. The initial ε_Nd of this array (−11.1 ± 2.0) suggests a crustal source. The mineralogical, geochemical, and isotopic datasets reconcile the Mbarga BIF prospect with arc magmatism in the Late Archaean, suggesting their formation in a back-arc basin setting.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"416 ","pages":"Article 107631"},"PeriodicalIF":3.2,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705704","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":"Reconstructing Tarim within Rodinia: Constraints from early Tonian accretionary and collisional records in the Altyn belt","authors":"Wei Li ,&nbsp;Jinlong Yao ,&nbsp;Guochun Zhao ,&nbsp;Yigui Han ,&nbsp;Qian Liu ,&nbsp;Donghai Zhang","doi":"10.1016/j.precamres.2024.107605","DOIUrl":"10.1016/j.precamres.2024.107605","url":null,"abstract":"<div><div>The position of the Tarim craton within Rodinia has long been debated, with competing models varying from internal to external ones. The Altyn belt in the southeast Tarim margin preserves extensive early Neoproterozoic magmatic successions, which are possibly related to the Rodinia assembly. Thus, we here investigated the granitoids in the South Altyn belt (SAB), and present field geology, zircon U–Pb–Hf–O isotopes and H₂O contents, and whole rock geochemistry data from these granitoids. The Tula granite is dated at 914 ± 3.9 Ma, whereas the Kuoshi granites are dated at 919 ± 5.2 Ma and 927.7 ± 5.0 Ma. The Tula and Kalaqiaoka granite samples display high ACNK values that are typical of S-type granitoids, consistent with the occurrence of garnet and muscovite. In addition, the Tula granite has higher zircon δ¹⁸O (7.62 to 10.85 ‰) and lower εHf(t) (−2.4 to +0.1) values, along with lower zircon H₂O content (medium values at 102 ppmw), indicating a primary water-deficient magma generated from recycled ancient crust, with minor juvenile contribution. On the other hand, the Kuoshi granite shows high Sr (169–259 ppm), Sr/Y (17.85–19.33) and (La/Yb)_N (30–49) ratios. The Kuoshi granites are also characterized by higher MgO, lower zircon δ¹⁸O (4.15 to 9.81 ‰) and εHf(t) (−4.0 to −0.4) values, higher zircon H₂O content (medium values at 255 ppmw), as well as subduction related chemical features. These signatures suggest that the Kuoshi granitic magma might have been formed by partial melting of recycled ancient crust and juvenile crust in a subduction setting. Thus, these granitoids across the SAB reflect a transformation from water-enriched subduction setting to water-deficient <em>syn</em>-collisional setting at ca. 930–920 Ma. Moreover, the zircon Hf isotope evolution trend across the SAB also suggest a possible transformation from slab retreat to <em>syn</em>-collision at 930–920 Ma. Furthermore, the end Mesoproterozoic and early Neoproterozoic metamorphic and magmatic events in the Tarim Craton, North Qaidam-Kunlun Block, Australia and India blocks display a close affinity. Therefore, we conclude a position of the Tarim craton between QKB, Australia and North India blocks in the periphery of Rodinia, consistent with earlier paleomagnetic data.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"416 ","pages":"Article 107605"},"PeriodicalIF":3.2,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705703","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}