Columbia Supercontinent Research Articles

Evolution of A-type granites during the Late Paleoproterozoic orogenic cycle of North China craton: Implications for post-collisional magmatism

“A-type” granites were originally considered anorogenic, however current consensus closely associates them with orogenic settings. The correlation between the prolific emergence of A-type granites and the assembly of the Columbia (Nuna) supercontinent during the Late Paleoproterozoic remains ambiguous possibly being indicative of a geodynamic shift from the amalgamation to the fragmentation of the supercontinent. This study identifies a Late Paleoproterozoic pluton exhibiting A2-type granite characteristics in the Shaerqin area of the Khondalite belt, North China craton. The plutonic rocks exhibit evolved whole-rock Nd isotopic (εNd(t) = −6.6 to −8.0) and zircon Hf isotopic (εHf (t) = −6.3 to −2.9) compositions, along with notably high zircon δ18O values (averaging 8.35 ± 0.29 ‰, 1SD). The Hf–Nd–O isotope systematics imply that the Shaerqin A-type granites originated from the partial melting of preexisting crustal materials under conditions of low pressure and high temperature. Incorporating the outcomes of this research with a compiled dataset of 1.9–1.5 Ga A-type granites across the entire craton, we deduce that: 1) Key geochemical ratios and indices, such as 10,000 Ga/Al, Y/Nb, and Zr/Nb, in A-type granites exhibit temporal variations, signifying a transition from A2-type to A1-type granite; 2) There is an increasingly apparent involvement of mantle-derived magmas in their genesis, coupled with a more pronounced role of fractional crystallization in the development of A1-type granites compared to their A2-type counterparts. We contend that these compositional and isotopic transitions reflect the tectonic evolution from post-orogenic extension to anorogenic rifting occurring around 1.7 Ga. The refined geochemical variations revealed in this study may offer a paradigm for post-orogenic evolutionary processes in general.

Paleoproterozoic positive δ13C excursion recorded in the carbonatite of southeast Tarim Craton, northwest China

The Paleoproterozoic Aketashitage carbonatite of northwest China is one of few high-δ13C carbonatites worldwide. Its absence of associated alkaline silicate rocks positions it as an intriguing case for probing the complex formation process of carbonatites. To provide further constraints on the genesis of these carbonatites, we have executed an exhaustive study encompassing petrography, geochemistry, geochronology, and radiogenic-stable isotope analysis. The Aketashitage carbonatites exhibit complex intrusive relationships with surrounding wall-rocks and house a diverse array of xenoliths, unmistakably signifying their igneous origin. Their rare earth elements (REE) diagrams are characterized by a nearly flat pattern and pronounced positive Eu anomalies, indicating a significant impact from hydrothermal fluids. These carbonatites are notably deficient in REEs, Ba, Sr, U, Th, Nb, and Ta. Their 143Nd/144Nd ratios and εNd (t) values range from 0.5109 to 0.5111 and −8.13 to −6.11, respectively. Remarkably, their δ13CV-PDB values (V-PDB, Vienna Pee Dee Belemnite) are exceptionally elevated, ranging from +13.31 to +15.48 ‰, thereby setting them apart from typical mantle-derived carbonatites, which exhibit δ13C values below 0 ‰. These comprehensive geochemical traits diverge significantly from those of mantle-derived carbonatites but share striking resemblances with crustal-origin carbonate rocks. Moreover, petrographic and mineralogical analyses reveal indicators of regional metamorphism within these carbonatites, proposing their possible for formation through the anatexis of high-grade marbles during the peak metamorphic event of the Paleoproterozoic era. Coupled with determined formation ages, these results imply a potential connection of Aketashitage carbonatites formation to the collision and amalgamation of the supercontinent Columbia. Moreover, the notable δ13C enrichment observed in these carbonatites presents substantial evidence for the impactful reach of the global Lomagundi-Jatuli event on the Tarim Craton.

Metamorphic turnover at 2 Ga related to two-stage assembly of Columbia

Understanding the stabilization of cratons and how this is related to the onset of plate-tectonics is among the most important questions in geoscience. The assembly of Earth’s first supercontinent Columbia represents the first lines of evidence for a global subduction network, when the oldest, deep subduction-related rocks have been reported. We combine the low-, intermediate- and high-T/P global metamorphic record with the two-stage assembly of the Nuna-Columbia supercontinent to address the significance of the oldest “cold” rocks (low-T/P) and the related emergence of bimodal metamorphic belts. For this purpose, we analyse two examples from Laurentia (including Greenland) and Australia between 2.0–1.8 Ga and 1.8–1.6 Ga. Two main observations are: (i) a first-stage (2.0–1.8 Ga) amalgamation of the megacontinent Nuna (precursor to Columbia) is characterized by bimodal metamorphism along major mobile belts suturing the megacontinent’s center. In contrast, a second-stage (1.8–1.6 Ga) is dominated by the formation of soft collisional orogens during the final Columbia supercontinent assembly, recording intermediate- to high-T/P metamorphism; (ii) the metamorphic signature of the two assembly stages, featuring low- and intermediate-T/P rocks during Nuna assembly followed by their near absence during Columbia amalgamation, contrasts with the thermobaric ratios recorded by the Phanerozoic Gondwana-Pangea assembly, where intermediate and low-T/P rocks dominated the final stage of Pangea amalgamation. This discrepancy may signify substantial changes in intraplate metamorphism and minor rearrangements during Columbia assembly compared to major continent–continent collisions, such as the Appalachian-Variscan Orogen as well as production and fast exhumation of high- to ultra-high-pressure rocks during the assembly of the supercontinent Pangea. Furthermore, the variation of thermobaric ratios aligns with the concept of a two-stage mega-supercontinent formation, emphasizing differences between the potentially oldest and youngest supercontinent cycles.

A uniform basement: Implications for the tectonics of Beishan Orogenic Belt in the southern Central Asian Orogenic Belt

The orogen is a significant window for studying the history and architecture of Earth; its architecture involves many significant issues. Currently, research on the architecture of orogenic belts mainly focuses on the process of orogeny, and few studies focus on the tectonics before the orogeny, which somewhat constrains orogen evolution. The nature of the basement(s) of microcontinents in the Beishan Orogenic Belt (BOB) in the middle Central Asian Orogenic Belt (CAOB) has been debated for a long time, which causes confusion about the tectonics of the BOB. This study conducted field surveys, geochronology, geochemistry, and Hf isotope analysis on the major microcontinents of BOB. The age information of ca. 1.4 Ga and the Paleoproterozoic-Archean with small scale were found in the northern BOB. The northern BOB (NBOB) and southern BOB (SBOB) (separated by the Hongliuhe-Niujuanzi-Xichangjing ophiolitic mélange belt) have experienced similar magmatic thermal events at ca. 1.4 Ga and ca. 0.9 Ga, which are revealed by the analogical tectonic setting, formation ages, and Hf isotopic features. The Precambrian basements of the NBOB and SBOB are analogous in terms of rock assemblages, detrital zircon ages, magmatic rock ages, εHf(t) of Precambrian rocks, and Hf crustal model ages TDMC of Paleozoic igneous rocks, which imply that they shared similar history and provenance and might originate from a uniform basement. The basement has no close tectonic affinity to the adjacent cratons or blocks, except the Baltica Craton and Laurentia Craton. And it might have been involved in the amalgamation of the Columbia Supercontinent and be situated on the periphery of the Rodinia Supercontinent, and then fragmented when the Rodinia Supercontinent rifted apart.

Indosinian anatexis of Paleoproterozoic granites in the east Cathaysia Block, South China

AbstractGranulite facies metamorphism and crustal anatexis exist in the East Cathaysia Block, the exact timing of granulite facies partial melting and its link with orogenesis have not been well constrained. In this study, we carried out petrography, whole rock geochemistry, and zircon U–Pb dating, trace elements and Hf isotopes analyses on Dazhe gneissic granite and banded migmatite from the Badu Group in southwest Zhejiang province in the East Cathaysia Block. The melts were produced through the dehydration of biotite, such as biotite + quartz + plagioclase = orthopyroxene + K‐feldspar + melt and biotite + quartz + plagioclase + sillimanite = garnet + K‐feldspar + melt. Zircons from these rocks show clear core‐rim structure and yield rim and core concordant ages at 233 Ma and 1.83 Ga, respectively. The zircon rims suggesting the melts and the cores are suggesting the protolith of Dazhe gneissic granite and banded migmatite were crystallized from an evolving magma. The zircon cores and rims have negative εHf(t) = −2.2 ~ −6.3 and εHf(t) = −22.8 ~ −32.4, and they give suggestion of the presence of Neoarchean components. Although the major‐element compositions of the gneissic granite and banded migmatite are slightly different, the trace‐element spider diagram and REE pattern show they are similar, and then we find that the protoliths are A‐type granodiorite/diorite. Combined with the published data, we suggested that the Dazhe gneissic granite and banded migmatite were formed through granulite facies partial melting at 233 Ma, which was promoted by crustal shortening and thickening of the collision orogeny between East Cathaysia Block and an unknown terrane with a NNE trend structure line. The protoliths (granite or granodiorite) of Dazhe gneissic granite and banded migmatite crystallized at 1.83 Ga by reworking of the Neoarchean components of East Cathaysia Block. The Paleoproterozoic (1912–1819 Ma) collisional orogeny and the later intraplate rifting stage are corresponding to the aggregation and breakup of the Columbia supercontinent.

Fluctuating oxygenation and dynamic iron cycling in the late Paleoproterozoic ocean

The mid-Proterozoic (1.8–0.8 billion years ago, Ga) is generally considered to have been an interval of relative stasis in terms of environmental and biological evolution. Indeed, in terms of ocean redox chemistry, deeper ocean waters are considered to have dominantly remained anoxic and ferruginous throughout this interval. Despite the persistence of ferruginous conditions, the mid-Proterozoic has long been considered notable for a general absence of iron formations (IFs), in stark contrast to the major intervals of IF deposition that occurred in the ferruginous oceans of the earlier Precambrian. In recent years, however, sporadic IFs have been found in the mid-Proterozoic, but controls on the genesis of these IFs, as well as implications for the evolution of ocean chemistry, remain poorly understood. Here, we present major and trace element data, iron speciation systematics, and organic carbon and iron isotope data for the ∼1.64 Ga Chuanlinggou Formation, which hosts a sudden reappearance of substantial IF deposition on the North China Craton. The Chuanlinggou IF has low Y/Ho ratios (24–26), slightly positive Eu anomalies (Eu/Eu* = 1.14–1.47), no Ce anomalies, slightly positive δ56Fe values (0.05 to 0.35 ‰), and high δ13Corg values (−29 ‰) relative to deeper water facies (down to −33.4 ‰). These observations provide support for a redox-stratified ocean with oxic surface waters overlying ferruginous deeper waters, and further suggest that IF deposition occurred in a stratified ocean with a shallow redoxcline during an interval of elevated Fe concentrations. Specifically, we suggest that the development of relatively intense ferruginous conditions was likely a consequence of hydrothermal activity during the breakup of the Columbia supercontinent. Microaerophilic iron-oxidizing bacteria and/or anoxygenic photosynthesizers likely played a key role in the generation of the Chuanlinggou IF. Importantly, however, data for shales that overly the Chuanlinggou IF suggest episodic intervals of deeper water oxygenation. Thus, similar to recent studies of the later Mesoproterozoic ocean, our data indicate that ocean chemistry during the latest Paleoproterozoic may have been more dynamic than previously considered, with fluctuating oxygen and iron levels likely exerting a limiting constraint on both the evolution of eukaryotes and the deposition of IFs across the immense interval of time encapsulated by the mid-Proterozoic.

Zircon U[sbnd]Pb and Hf isotope insights into the Mesoproterozoic breakup of supercontinent Columbia from the Sausar Belt, Central Indian Tectonic Zone

Credible records of rifting and associated sedimentation and granitoid magmatism coinciding with the Columbia breakup event are not common in the Precambrian Indian continent. We report a 1322 ± 3 Ma concordia age for magmatic zircons from the granitoid rocks of the Sausar mobile belt, Central Indian Tectonic Zone (CITZ). The rocks exhibit geochemical characteristics of A-type granitoid rocks and were generated by the dehydration melting of shallow crust in an extensional tectonic setting. The predominantly negative εHf(t) values and partial melting modelling imply their origin by the reworking of pre-existing granitoid crust. TDM2 (Hf) model ages for these rocks range from 2856 Ma to 1885 Ma suggesting a prolonged period of crustal evolution and reworking of Archean to Paleoproterozoic basement rocks. The temperature for magma generation, determined from the calculated zircon saturation temperature of 874.2 °C is suggestive of melting of a thinned crust that was heated by the upwelling asthenosphere in an extensional tectonic setting. The obtained ages provide evidence for the existence of an extensional event during mid-Mesoproterozoic coinciding with the Columbia breakup event. The extension could also be argued as a local event related to far-field stresses generated due to the ca. 1.6 to 1.5 Ga subduction-collision event at the plate margin farther to the north of the studied region of the CITZ. The recrystallized margins of zircon grains yield 207Pb/206Pb ages between 0.95 Ga and 1.0 Ga implying their alteration during a metamorphic event that can be identified with the final amalgamation and stabilization of the northern and southern Indian blocks along the CITZ, coinciding with the Rodinia assembly, during which the regional structural fabric developed.

Rhyacian to Orosirian short-lived polyphase deformation and migmatization in northernmost São Francisco Craton, Brazil

The Minas-Bahia Orogen, which is Siderian-Orosirian age, is exposed in the northern sector of the São Francisco Craton and in its African counterpart, the Congo Craton. In this sector, two orogenic domains outcrops with geological evolution and terrains with different trends: Western and Eastern Bahia. The advance of scientific knowledge in the northeast of the West Bahia Orogenic Domain has revealed the existence of more tectonic terrains than those traditionally delimited, and reveal the presence of juvenile terranes and cratonic crust separated complex zones where they interacted. The region of interaction between the Gavião and Bom Jesus da Lapa Paleoplate has been the subject of debates about the tectonic significance of granulitic rocks with Meso-Neoarchean protoliths, which are intruded by Rhyacian - Orosirian granitoids. The set of geological data presented in this article demonstrates that the metatexite migmatites with felsic granulitic paleosome and charnockitic neosome were generated during the initial phases of the collision between these two paleoplates, between 2068 and 2058 Ma. The structural mass transport is from NW to SE. The youngest migmatization event, in high amphibolite facies, occurred during NNW-SSE trending sinistral strike-slip tectonics as suggested by the emplacement of Dn+3 neosomes controlled by S/C/C' structures, in between 2049–2000 Ma. The interpreted tectonic model is complex and involves the accretion and collision among Bom Jesus da Lapa, Gavião and Jequié paleoplates during the Rhyacian-Orosirian, contributing to the advancement of knowledge of tectonic pieces and their interactions that contributed to the formation of Columbia supercontinent.

Changes in orogenic style and surface environment recorded in Paleoproterozoic foreland successions

The Earth’s interior and surficial systems underwent dramatic changes during the Paleoproterozoic, but the interaction between them remains poorly understood. Rocks deposited in orogenic foreland basins retain a record of the near surface to deep crustal processes that operate during subduction to collision and provide information on the interaction between plate tectonics and surface responses through time. Here, we document the depositional-to-deformational life cycle of a Paleoproterozoic foreland succession from the North China Craton. The succession was deposited in a foreland basin following ca. 2.50–2.47 Ga Altaid-style arc–microcontinent collision, and then converted to a fold-and-thrust belt at ca. 2.0–1.8 Ga due to Himalayan-style continent–continent collision. These two periods correspond to the assembly of supercratons in the late Archean and of the Paleoproterozoic supercontinent Columbia, respectively, which suggests that similar basins may have been common at the periphery of other cratons. The multiple stages of orogenesis and accompanying tectonic denudation and silicate weathering, as recorded by orogenic foreland basins, likely contributed to substantial changes in the hydrosphere, atmosphere, and biosphere known to have occurred during the Paleoproterozoic.

Late Neoarchean and Paleoproterozoic tectonothermal and metamorphic evolution recorded in high-pressure granulites: Evidence from the Xuanhua Complex, northern North China Craton

Archean cratons usually underwent reworked processes during the late Paleoproterozoic orogeny, which may result in multiple tectonothermal records preserved in some high-grade metamorphic rocks; thus, these rocks provide a key opportunity on understanding the tectonic styles during different periods. In this study, we report new petrological, mineral chemical and geochronological data of a suite of newly discovered mafic and felsic metamorphic rocks in the Xuanhua Complex from the northern North China Craton (NCC), revealing the complex metamorphic thermal history and the transition of tectonic regime from the late Neoarchean to the late Paleoproterozoic. The mafic granulite preserves the prograde quartz and clinopyroxene inclusions within garnets (M1), and the peak stage (M2) is recorded by garnet, clinopyroxene, hornblende, plagioclase, quartz and ilmenite. The first retrograde (M3a) and final cooling stages (M3b) are defined by the appearance of orthopyroxene, and the amphibolite-facies overprinting, respectively. The felsic granulite records the similar peak mineral assemblage (M2), but has higher volumes of feldspar and quartz than the mafic granulite. The retrograde stage (M3) is represented by amphibolite-facies assemblage (hornblende ± biotite ± clinopyroxene) and fine-grained intergrowth of hornblende + plagioclase around garnet. Pseudosection modeling and thermobarometry results suggest that both high-pressure (HP) mafic and felsic granulites record clockwise P–T paths, including isothermal decompression and cooling from the peak stage (M2: 10.4–10.8 kbar/830–860 °C and 9.6–11.2 kbar/850–930 °C, respectively) to the retrograde stages (M3a and M3b: 7.5–8.0 kbar/840–870 °C and 7.8–8.2 kbar/650–700 °C, respectively; M3: 7.2–8.6 kbar/670–800 °C). Zircon U–Pb dating shows that the magmatic precursors of these rocks were emplaced at c. 2.5–2.47 Ga. The metamorphic zircons reveal two groups metamorphic ages of c. 2.51–2.45 Ga and c. 1.90–1.85 Ga. The c. 2.51–2.45 Ga ages indicate a late Neoarchean tectonothermal event, and the c. 1.95–1.85 Ga ages are interpreted to represent the Paleoproterozoic HP granulite-facies metamorphism overprinting. The highest positive εHf(t) value of 7.64 and 2.8–2.6 Ga Hf model ages of c. 2.5 Ga magmatic zircons indicate that the c. 2.5 Ga mantle-derived mafic magma and the c. 2.5 Ga partial melting of 2.8–2.6 Ga basaltic juvenile crust generated the protoliths of mafic and felsic granulites, respectively, revealing 2.8–2.6 Ga and 2.5 Ga crustal growth and c. 2.5 Ga crustal reworking in the northern NCC.To sum up, we consider that the late Neoarchean magmatism and coeval metamorphism recorded in our samples are probably resulted from the amalgamation of micro-blocks. The Paleoproterozoic clockwise P–T–t paths with near-isothermal decompression segments and low geothermal gradients (c. 21–26 °C/km) of HP mafic and felsic granulites indicate a rapid post-collisional exhumation process after the significantly crustal thickening, and this long-term orogeny along the TNCO (c. 1.95–1.85 Ga; > 100 Myr) is related to the incorporation of the NCC into the Columbia supercontinent.

Paleoproterozoic crustal evolution of the Tarim Craton, NW China: Constraints from geochronology and geochemistry of orthogneisses and granitic veins in the Xingdi region of the Quruqtagh Block

The Archean–Paleoproterozoic basement rocks, exposed in the Xingdi region of the Quruqtagh Block, provide a great opportunity to characterize the early crustal evolution of the Tarim Craton and reconstruct the Columbia supercontinent. Here we report zircon U–Pb ages, Lu–Hf isotope compositions, and bulk-rock geochemical data of orthogneisses and granitic veins from the Xingdi region of the Quruqtagh Block in the northeastern margin of the Tarim Craton. The orthogneisses formed in the late Neoarchean to early Paleoproterozoic (2504 ± 33 Ma, 2419 ± 24 Ma and 2450 ± 27 Ma), and were metamorphosed in the late Paleoproterozoic (1789 ± 43 Ma and 1748 ± 35 Ma). The orthogneisses have relatively high Sr (312–710 ppm) contents, and low Y (5.3–13.8 ppm) and Yb (0.46–1.10 ppm) contents, resulting in high Sr/Y (32–118) and La/Yb (17–64) ratios that are characteristics of adakites. The relatively high Mg# (49–55) and depleted zircon Hf isotope characteristics (positive εHf(t), with TDM2 of ca. 2.5–2.8 Ga) indicate that the orthogneisses crystallized from partial melting of garnet-bearing amphibolite in a subduction environment. The granitic veins that intrude the orthogneisses formed during the late Paleoproterozoic (1760 ± 25 Ma), which is roughly contemporaneous with the metamorphic ages of the orthogneisses; the granitic veins are characterized by extremely high SiO2 (>80 %), enrichments in Rb, Ba and U, and depletions in Nb and Ta. It is inferred that the granitic veins formed by in situ anatexis of the orthogneisses during the late Paleoproterozoic. Based on the zircon ages with Hf isotope compositions, it is evident that the continental crust in the Xingdi region of the Tarim Craton largely formed between 2.5 and 2.8 Ga and was reworked at ca. 1.8 Ga; this evolutionary history is similar to that of the Dunhuang Block. Comparison of the Paleoproterozoic tectono-thermal events in the different terranes of the Tarim Craton, it is suggested that the Tarim Craton is composed of discrete terranes that detached from different ancient cratonic nuclei prior to the late Paleoproterozoic, and assembled within the Columbia supercontinent respectively.

Neoarchean to Paleoproterozoic crustal evolution of the central Aravalli-Banded Gneissic Complex (NW India): Evidence from zircon U-Pb-Hf isotope systematics and whole-rock composition of Neoarchean sanukitoids, Paleoproterozoic granitoids and metasedimentary rocks

The central Aravalli-Banded Gneissic Complex in NW India is an Archean nucleus that was extensively reworked during the late Paleo- to Neoproterozoic. New results of combined zircon U-Pb-Hf isotopes and whole-rock geochemical data reveal that the basement was affected by felsic magmatism during the Neoarchean and Paleoproterozoic, followed by a passive margin stage. The results provide evidence for coeval emplacement of sanukitoids and TTGs at ca. 2540 Ma, and for granitoid magmatism at ca. 1875 Ma. Similar REE patterns of the synchronous sanukitoids and TTGs, coupled with high SiO2 contents (59.2–70.9 wt%), subchondritic εHf2.55 Ga values (−5.0 to −2.6) and Hf-model ages (3246–3123 Ma) of the Masuda sanukitoids indicate that the sanukitoid magmas were formed mainly by interaction of TTG magmas (generated by the melting of subducted Paleo- to Mesoarchean oceanic crust) with the overlying enriched peridotite. The calc-alkalic and magnesian compositions, enrichment in LREE and LILE along with pronounced depletion in HFSE (Nb, P and Ti) in ca. 1875 Ma granitoid gneisses imply subduction-related magmatism during Paleoproterozoic. The predominance of subchondritic εHf1.87 Ga values, ranging from −4.4 to +1.7, suggests that the parental magmas mainly resulted from the reworking of heterogeneous Meso- to Neoarchean felsic crust. Age-Hf isotope data of detrital zircon grains provide evidence that clastic sedimentary rocks covering the central Aravalli basement were deposited in a passive margin setting at < 1730 Ma, and the detritus was mainly sourced from adjoining Neoarchean and Paleoproterozoic granitoids. Comparison of our new data with other Indian and worldwide cratons indicate that the Aravalli orogen represents a unique terrane, where the Neoarchean TTGs and sanukitoids with subchondritic Hf isotopic signatures were emplaced nearly coeval in a close spatial relationship. The Aravalli Archean basement was subsequently reconfigured by voluminous felsic magmatism during Paleoproterozoic at 1875–1810 Ma. Furthermore, the compiled zircon U-Pb age and Hf-Nd isotope data for the late Paleoproterozoic subduction-related magmatic rocks provide evidence for substantial crustal reworking during assembly of the Columbia supercontinent.

Mid-Mesoproterozoic (ca. 1.37 Ga) anorogenic magmatism in the Dabie orogen, northern Yangtze Craton: Response to the breakup of Columbia

It is evident that the Yangtze Craton was involved in the formation and breakup of the Columbia supercontinent. However, due to the scarcity of Mesoproterozoic geological records and reliable paleomagnetic data, little is known about the timing, paleogeographic position, and geological processes of the Yangtze Craton. We conducted detailed geological mapping, petrographic, geochemical, and in situ zircon U-Pb and Lu-Hf isotopic investigations on newly recognized Mesoproterozoic quartz syenite and monzogranite in the Dabie orogen, northern Yangtze Craton. The results show that the quartz syenite and the monzogranite were emplaced at 1369 ± 12 Ma and 1372 ± 5 Ma, respectively. Both rocks are high in total alkali (K2O + Na2O) content and FeOt/(FeOt + MgO), with elevated diagnostic 10,000*Ga/Al ratios and Zr + Nb + Ce + Y concentrations, and enrichment in light rare earth elements. They are also depleted in heavy rare earth elements with significant negative Eu anomalies but remarkably low Sr, Cr, and Ni contents. These compositions define affinity to A1-type granite. In addition, the quartz syenite displays variable zircon Hf and homogeneous whole-rock Nd isotopic compositions with positive εHf(t) values of +0.7 to +5.7 (average +2.4) and εNd(t) values of −0.1 to +2.5 (average +1.0). In contrast, the monzogranite has homogeneous zircon Hf and whole-rock Nd isotopic compositions with negative εHf(t) values of −5.7 to −2.6 (average −4.8) and εNd(t) values of −3.5 to −1.5 (average −2.2). We propose that the quartz syenite was likely generated by the partial melting of juvenile, crust-derived melt with involvement of minor mantle-derived material, while the monzogranite was likely derived from the partial melting of ancient crust in an extensional tectonic regime (e.g., continental rift). Based on the newly recognized ca. 1.37 Ga granitic magmatism and previously reported magmatic events, we argue that the mid-Mesoproterozoic (ca. 1.37 Ga) magmatism in the Yangtze Craton occurred in response to the breakup of Columbia, and represents the separation of the Yangtze Craton from Columbia. Furthermore, according to comparable magmatic and sedimentary events, we propose that the Yangtze Craton, along with central Hainan Island, may have been linked to northwestern Laurentia, southwestern Siberia, and northeastern Australia during 1.6−1.4 Ga.

Archean to Paleoproterozoic magmatic and metamorphic evolution of the Lofoten – Vesterålen area in northern Norway through zircon U-Pb and Hf isotopic analysis

Neoarchean (2.8–2.5 Ga) and Paleoproterozoic (2.5–1.6 Ga) crust preserves a record of major crustal growth events, the oldest supercontinent assemblies, and the likely transition to modern plate tectonics. The Lofoten–Vesterålen area in Norway underwent a multistage tectono-magmatic history from the Neoarchean to the Paleoproterozoic. In this region three main components are distinguished: 1) a granulite facies zone (GFZ); 2) an amphibolite facies zone (AFZ); and 3) an anorthosite-mangerite-charnockite-granite (AMCG) suite. New zircon U-Pb and Lu-Hf isotope data are used to investigate the evolution of this 2.7–2.6 and 1.9–1.8 Ga crust and evaluate how the developments fit in the global context of Earth’s crustal evolution. In-situ LASS–MC-ICPMS analyses were conducted on zircons to simultaneously determine U-Pb ages and Hf isotope compositions. Solution Hf isotope compositions were additionally obtained on zircons previously dated by ID-TIMS. In general, there is a good agreement between solution and in-situ data. Samples from the GFZ and AFZ both yield Neoarchean (2.7–2.6 Ga) and Paleoproterozoic (1.9–1.8 Ga) populations. Neoarchean populations have εHf(i) of +0.9 to −0.3; Paleoproterozoic populations have εHf(i) around −16 and −7 at ∼1.80 and ∼1.87 Ga, respectively. The AMCG suite was emplaced in two magmatic pulses: the early one at 1.87–1.86 Ga characterized by εHf(∼1.87 Ga) ∼ −7, and the main pulse at 1.80–1.79 Ga has εHf(∼1.80 Ga) between −4.0 and −15.0. Metamorphic overprinting recorded within the GFZ and the AMCG at ∼1.80 Ga is absent in the AFZ, supporting the hypothesis of a tectonic boundary between these domains. The Hf isotope compositions suggest that Paleoproterozoic magmatism was sourced from a combination of juvenile material and incorporated ancient crust, probably in variable proportions, as suggested by the variation in the isotope composition of the AMCG suite. Broadly chondritic Hf isotope compositions in Neoarchean rocks indicate the absence of significantly older crust as a source component. Main crustal growth events recorded in the Lofoten–Vesterålen area coincide with global age peaks and zircon Hf isotope record. The AMCG suite was emplaced during the Columbia supercontinent assembly. Neoarchean and Paleoproterozoic crust in the Lofoten–Vesterålen area exemplifies the elevated preservation potential in collisional tectonic settings.

Geochemistry and petrology of the Chandarpur-Raipur sandstones: Implications for the evolution of the Chattisgarh Basin, Central India

Depositional processes and stratigraphic evolution of the Chattisgarh basin exhibit a synergistic relation between sedimentation and tectonics. To interpret the sedimentation history and basin evolution, multiproxy approach including field studies, petrography, geochemical, and multivariate statistical analyses of the sandstones of Chandarpur and Raipur groups is employed. The study provides a detailed analysis of the time-connoted petrography and geochemistry of the sandstone units from each formation of the Chandarpur-Raipur sequence of Chattisgarh basin. The sandstones grade from immature wacke through submature arkose to mature quartzarenite from the bottom up the section. These sandstones are broadly characterized by felsic provenance, arid-humid palaeoclimate, and weak-intense palaeoweathering at the source. The assemblage of wacke-arkose-sublitharenite of the basal Lohardih Formation is characteristics of fan delta environment and represents initiation of rifting and basin formation stage. Subarkoses from the younging up sequence of Lohardih-Chaporadih-Kansapathar formations reflect prograding shelf environment that represents craton interior field of the continental block provenance and passive marginal tectonic setting, indicating gradual stabilization of the basin. Quartzarenites from Kansapathar Formation and stratigraphically younger Devsagar Member of Charmuria Formation also represent broadly similar provenance and tectonic setting indicating stable craton interior provenance in a passive marginal setting. Petrographic and geochemical analyses of some of the Kansapathar-Devsagar sandstones suggesting recycled orogen provenance, however, may be attributed to the orogenic activity and/or role of younger bimodal volcanic rock during rejuvenation of multistage basin opening faults. Rifting stage was followed by subsidence stage as indicated by the presence of black limestone capping the sandstone successions. Initiation of basin formation ∼1400 Ma and sedimentation can be correlated with the late-stage fragmentation of the supercontinent Columbia. The basin probably closed ∼1000 Ma during the assembly of the next supercontinent Rodinia. It is estimated that ∼87% of the 2.2-km-thick sedimentary succession in the eastern Chattisgarh basin, were already deposited within this time frame (∼1405 and ∼1007 Ma). The basin is correlatable with other Mesoproterozoic basins of Peninsular India like Vindhyan, Cuddapah basins, as well as with basins like Xiong’er rift basin of North China Craton, Espinhaco basin of eastern Brazil, that are related to the Columbia-Rodinia Supercontinent cycle.

A craton‐like subcontinental lithospheric mantle beneath the Trans‐North China Orogen revealed by the ca. 1.54 Ga kimberlites

AbstractAncient orogens within the supercontinent like Columbia can remain stable evolution as long as the cratons. What kind of lithospheric mantle was beneath those orogens and how it evolved into a stable state are still enigmatic. The Trans‐North China orogen (TNCO) is one of the typical collisional orogens within the Columbia supercontinent and was formed at ca. 1.85 Ga. Our work reveals that a cluster of kimberlites intruded the orogenic belt at ca. 1.54 Ga. These rocks were originally generated under a thick lithosphere (&gt;200 km). Their entrained olivine cores show a composition of overlapping olivines from refractory mantle peridotites. The results suggest a thick and refractory lithospheric mantle beneath the TNCO at ca. 1.54 Ga. Such craton‐like property may result from large volume melt extraction from the lithospheric mantle, possibly caused by the ca. 1.78 Ga large igneous event, which eventually induces the long‐term stability of the TNCO during the subsequent supercontinent cycle.

Paleomagnetism and geochronology of the Gwalior Sills, Bundelkhand craton, Northern India Block: New constraints on Greater India assembly

We present an updated paleomagnetic pole from the Gwalior Sills in the Bundelkhand craton within the Northern India Block (NIB). Geochronological results from baddeleyite grains from one of the sills yielded an age of 1719 ± 7 Ma which together with a previously published age indicates the emplacement of sills between 1712 and 1756 Ma (∼1730 Ma). The paleomagnetic pole calculated from additional sites in this study, combined with previous studies, falls at 13.5°N, 173.7°E (A95 = 3.6°, K = 98) indicating near equatorial latitudes for northern India. Limestone sampled a few meters above the contact with the sill exhibits similar directions consistent with having been baked by the sill. The pole does not resemble any younger poles from Peninsular India and receives a reliability score of R = 5. Dykes in the Singhbhum craton are slightly older (1765 Ma) and indicate low paleolatitudes for the Southern Indian Block (SIB). Although the Gwalior and Singhbhum poles data indicate low latitudes for both the NIB and SIB, they are statistically different and indicate that a rotation of at least 65° is required to bring the poles into accord. We propose that the NIB and SIB were in proximity but were separated by an ocean basin. We propose the name Gotosindhu (‘Ancient Sea’) for the body of water separating the NIB and SIB. We also review previous models for the assembly of the Columbia supercontinent during this time and critically examine the position of the NIB/SIB in those reconstructions.

U-Pb ages of detrital zircon and monazite from beach placers in Sri Lanka: Implications for configuration of the Columbia supercontinent

U-Pb ages of detrital zircon and monazite from beach placers in Sri Lanka: Implications for configuration of the Columbia supercontinent

The Earliest Clastic Sediments of the Xiong’er Group: Implications for the Early Mesoproterozoic Sediment Source System of the Southern North China Craton

The volcanic activity of the Xiong’er Group and its concomitant sedimentation are related to the stretching–breakup of the Columbia supercontinent. The Dagushi Formation overlies the Paleoproterozoic Shuangfang Formation with an angular unconformity. The Dagushi Formation, as the earliest clastic strata of the Xiong’er Group and the first stable sedimentary cover overlying the Archean crystalline basement in the southern margin of the North China Craton, provides tectonic evolution information that predates Xiong’er volcanic activity. By distinguishing lithologic characteristics and sedimentary structures, we identified that the sedimentary facies of the Dagushi Formation were braided river delta lake facies from bottom to top. The U–Pb ages of the detrital zircons of the Dagushi Formation can be divided into four groups: ~1905–1925, ~2154–2295, ~2529–2536, and ~2713–2720 Ma, indicating the provenance from the North China Craton basement. Based on the geochemical characteristics of the Dagushi Formation, we suggest that the sediments accumulated rapidly near the source, which were principally felsic in nature, and were supplemented by recycled materials. The provenance area pointed to the underlying metamorphic crystalline basement of the North China Craton as the main source area with an active tectonic background. The Chemical Index of Alteration (CIA) values of the Dagushi Formation sandstone samples ranged from 60.8 to 76.7, indicating that the source rocks suffered from slight to moderate chemic chemical weathering. The Index of Composition Variability (ICV) values ranged from 0.8 to 1.3, which indicates the first cyclic sediments. The vertical facies and provenance changes of the Dagushi Formation reflect a continuous crust fracturing process that occurred in the North China Craton.

Characteristics and genetic mechanism of the Mesoproterozoic rift system, Ordos Basin, China

The Mesoproterozoic rifts are developed in the Ordos Basin located in the western margin of the North China Plate. Based on the latest 3D seismic data and previous research results, this study intends to discuss the zonal differential deformation characteristics and genetic mechanism of the Mesoproterozoic rifts in the Ordos Basin. NE-trending rifts are developed in the Mesoproterozoic in the south-central Ordos Basin, the main part of which are located near the western margin of the North China Plate. NNW-trending rifts are developed in the north of the basin, while NW-NNW rifts in the Mesoproterozoic in Hangjinqi area. The genetic mechanism of the Mesoproterozoic rifts is related to regional extensional stress field, plate boundary conditions and internal preexisting structures. The main extensional stress direction strikes NWW-SSE (120°) in the western margin of the North China Plate, based on the forward rift trend of the northern Mesoproterozoic. In Hangjinqi area, the reactivation of the existing NW-trending Wulansu fault and NW-NW-trending Daolao fault, results in dextral shear stress field. The boundary between the western margin of the North China Plate and its adjacent plates forms a nearly NS-trending preexisting basement tectonic belt, which intersects with the NWW-SSE (120°) extensional stress at an acute angle of 60°. Therefore, the western margin of the North China Plate is formed by oblique normal faults under oblique extension. Due to the long time span of Columbia Supercontinent breakup (1.8–1.6 Ga), the oblique rift in the south-central Ordos Basin is formed under the continuous oblique extension at the western margin of the North China Plate.