Breakup Of Columbia Research Articles

Late Paleoproterozoic within-plate mafic magmatism in the western Yangtze Block, South China Craton: Implications for the initial break-up of the Columbia supercontinent

The Paleoproterozoic was an important period for the tectonic-magmatism evolution of the Yangtze Block, which coincided with the assembly and break-up of the global Columbia (also known as Nuna) supercontinent. However, an essential issue, when the Yangtze Block initiated rifting from the supercontinent, remains controversial. This paper presents new zircon chronology, Lu-Hf isotopic data, and whole-rock geochemical analyses of the Bajiaojing and Xiaoqingshan meta-diabases in the western Yangtze Block to address this issue. The magmatic zircons from the Bajiaojing and Xiaoqingshan meta-diabases yielded U-Pb ages of 1675 ± 38 Ma and 1719 ± 10 Ma, representing an episode of mafic magmatism during the Late Paleoproterozoic. Moreover, the abundances and elemental ratios of high-field-strength elements (HFSEs, e.g., Y, Ta, Th, and Hf) in both meta-diabases are very similar to those of within-plate and mantle plume magmas. This implies that these Late Paleoproterozoic mafic rocks were likely derived from a mantle plume source in a continental within-plate extensional setting. Their magmatic source was relatively heterogeneous in isotopic and geochemical compositions, as inferred from significant differences in εHf(t) values and certain HFSE ratios (e.g., Nb/Yb, Ta/Yb, Th/Yb, Nb/Y, and Zr/Y) among samples. Such source heterogeneity might be attributed to interactions between the mantle plume and the overlying lithosphere. Combined with published εHf(t) values of detrital zircons and whole-rock εNd(t) values of (meta-)magmatic rocks, we speculate that the Yangtze Block experienced a tectonic transition from plate convergence to continental extension at ∼ 1.7 Ga. This means that the block began to rift from the Columbia supercontinent as early as 1.7 Ga. The Yangtze Block then evolved progressively as an isolated fragment until it was amalgamated into the Rodinia supercontinent.

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.

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.

Nature of early Mesoproterozoic magmatism in the Qilian-North Qaidam tectonic belt, NW China: Implications for prolonged extension processes and transition from Columbia to Rodinia

Precambrian basement rocks exposed in uplift zones and orogenic belts provide accessible opportunities for paleogeographic reconstruction, especially for microcontinents and cratons with thick covers. Here we report early Mesoproterozoic rifting-related mafic and granitic metaigneous rocks preserved in the Qilian-North Qaidam tectonic belt, NE Tibetan Plateau. Mafic rocks include garnet amphibolite emplaced at 1.40 Ga and metagabbro that were emplaced at 1.39 Ga, exposed in the North Wulan area. They are derived from low-degree (<7 %) partial melting of slab-modified lithospheric mantle lherzolites with Sp:Grt ranging from 90:10 to 60:40. The calculated low P-T conditions of mantle melting (Tpmax < 1472–1451 °C at P = 2.0 Ga) are also consistent with a thermal normal lithospheric mantle upwelling event. Granitic rocks comprise ca. 1.44 Ga garnet-bearing and ca. 1.41 Ga two-mica granites that were emplaced in the North Wulan and Central Qilian areas, respectively. They are S-type granites derived from crustal reworking of psammitic-rich and/or clay-rich metasedimentary rocks. In addition, the two-mica granites represent the oldest basement rocks yet identified in Central Qilian and indicate the existence of ancient basement rocks older than ca. 1.41 Ga. All the mafic and granitic rocks belong to a part of intense Mesoproterozoic rift-related magmatism in the composite Qilian-Quanji block (QQB), and subsequently underwent 1.18–0.9 Ga metamorphic modifications. The composite QQB in the NE Tibetan Plateau was involved in the long-term processes including crustal reworking and mantle upwelling (1.5–1.35 Ga) correspond to the breakup of Columbia followed by oceanic subduction (1.2–1.0 Ga) and subsequent collision and exhumation (0.9–0.8 Ga) at the periphery of Rodinia. Our results improve the understanding of the Mesoproterozoic tectonic evolution for the whole QQB and provide important constrains on the transition from Columbia to Rodinia.

Newly discovered ca. 1.6 Ga K-bentonite layers from the Lakharpata Group in Nepal Lesser Himalaya: Implications for basin evolution during the Columbia breakup

• Zircon U-Pb age for newly discovered K-bentonite (ca. 1.6 Ga) constrained the deposition time of the Lakharpata Group. • The Lakharpata Group in Nepal Lesser Himalaya is coeval sediment with the Lower Vindhyan in India. • The Lakharpata Group was deposited in a passive continental margin basin during the Columbia breakup. The Lakharpata Group, a set of marine sediments with a thickness of over 5000 m, occupies the middle part of the Lesser Himalayan sequence and records important tectono-sedimentary evolution in the northern margin of the Indian continent. However, the duration of deposition and tectonic background of the Lakharpata Group are poorly defined. This study presents zircon U-Pb ages and Hf isotopes, as well as petrochemical data for the newly discovered K-bentonite layers in the Aru Formation, the upper part of the Lakharpata Group. Integrating the detrital zircon ages of the underlying metasedimentary rocks and the sedimentation rate of dolomite in the South China Block, we suggest that the Lakharpata Group was deposited during the late Paleoproterozoic to early Mesoproterozoic (ca. 1680–1580 Ma) rather than from Mesoproterozoic to Early Paleozoic as previously presumed. Stratigraphic correlations show the Lakharpata Group in Nepal Lesser Himalaya correlates to the Lower Vindhyan Supergroup, as well as to the Deoban and Rautgara formations in Kumaun Lesser Himalaya and the Baxa Group in Sikkim Lesser Himalaya, India. The Lakharpata Group comprises two depositional sub-sequences that record two transgression-regression sedimentary processes, which are comparable to the Lower Vindhyan. Geochemical and sedimentological studies suggest that the Lakharpata Group may represent the deposition of a passive continental margin basin during the breakup of the Columbia supercontinent.

Precambrian Tectonic Evolution of Southern Kongling Terrane, Yangtze Craton: Constraint From the Detrital Zircon U‐Pb Geochronology of the Metasedimentary Rocks

AbstractThe Kongling terrane (Huangling dome) outcrops Precambrian metamorphic basement of the Yangtze craton. However, the Precambrian tectonic evolution of the southern Kongling terrane remains poorly constrained. In this contribution, we report zircon geochronology of the metasedimentary rocks from southern Kongling terrane of the Yangtze craton. Zircon U‐Pb dating results yielded magmatic age clusters at ca. 3,000 Ma, ca. 1,520 Ma, ca. 1,150 Ma, ca. 860 Ma, 900–920 Ma, and 980 Ma, and metamorphic age at ca. 2,900 Ma. These data display that the southern Kongling terrane witnessed Mesoarchean magmatism and metamorphic event, Mesoproterozoic and Neoproterozoic magmatism. In combination with previous studies, it is proposed that the Precambrian metamorphic basement of the Yangtze craton was amalgamated by the multi‐stage subduction‐collision processes at ca. 3,000–2,900 Ma, ca. 2,000–1,800 Ma, and ca. 1,100–940 Ma. In addition, the Proterozoic processes were related to the assembly and breakup of Columbia and Rodinia supercontinents.

Mesoproterozoic accretionary orogenesis: Evidence from ∼ 1.4 Ga metamorphism on the southeastern margin of the North China Craton

The Mesoproterozoic period has always been thought of as an orogenic quiescence stage. However, contemporaneous magmatism and metamorphism indicate that this period was relatively restless. A Mesoproterozoic metamorphic event (~1.4 Ga) was first discovered in the southeastern part of the North China Craton. Samples, including garnet amphibolite and its countryrock biotite plagiogneiss, were collected from Rushan city on the Jiaodong Peninsula. The major elements of the rock are characterized by high Ti, where the trace elements show slight depletions in Th, U and Sr contents, and the REEs show E-MORB like patterns. The mineral assemblage of the garnet amphibolite includes garnet, hornblende and plagioclase. These metamorphic minerals are also found in zircons as inclusions. Cloudy and homogeneous CL images and flat HREE patterns of zircon trace elements in garnet amphibolite indicate a metamorphic origin, and zircon U-Pb age dating obtained an ∼ 1.4 Ga metamorphic age, which is consistent with the second age group age of the countryrock. Our dating results suggest that the Meoproterozoic metamorphic event in the North China Craton is comparable to metamorphic events reported in the Laurentian and Australian Cratons. Similar magmatism and comparable stratigraphy of these ancient cratons also support the Mesoproterozoic era was not an orogenic quiescence stage. Therefore, we infer a giant orogenic belt that existed along the outer margin of the supercontinent of the Columbia in the Earth’s middle age. Long-lived Mesoproterozoic accretionary orogenesis probably affected the edges of supercontinents in a transition stage from the breakup of Columbia to the assembly of Rodinia.

Linking ∼1.4–0.8 Ga volcano-sedimentary records in eastern Central Asian orogenic belt with southern Laurentia in supercontinent cycles

The record of Meso- to Neoproterozoic magmatism and sedimentation from the western Xing’an-Airgin Sum Block (XAB), eastern Central Asian Orogenic Belt (CAOB), provides the first key evidence for the close affinity between XAB and southern Laurentia, as well as the linkage with the supercontinent cycles. The ∼ 1.4 Ga calc-alkline granite-rhyolite association within the western XAB was probably the product of extension on a long-lived retreating convergent margin during the Columbia breakup, remarkably similar to the coeval Granite-Rhyolite Province in the southern Laurentia. Siliciclastic, mixed clastic and carbonate sequences of the Airgin Sum Group accumulated on the western XAB during two stages at 1.00–0.92 and 0.87–0.75 Ga, which were comparable with the syn- to post-orogenic successions on the southern Laurentia margin representing two dominant phases of the Grenville orogenic cycle in the Rodinia assembly. The Columbia breakup to Rodinia assembly also correlated well with the shift of zircon Hf isotope from a long-term juvenile crustal growth (1.6–1.2 Ga) to the rapid crustal reworking (1.1–0.8 Ga), and with the changes of zircon trace elements over time in the western XAB. The ever-growing new discovery of predominant 1.5–1.3, 0.9–0.8 Ga detrital zircon age peaks and coeval magmatism in many blocks worldwide suggests that they recorded much more intense magmatic activity, exhumation and deposition than previous thought. Juvenile crustal growth underestimated in previous researches, occurred extensively in blocks within the CAOB and Columbia at ∼ 1.5–1.3 Ga, and crust reworking significantly dominated the crustal evolution during the Rodinia assembly in 1.1–0.8 Ga.

Meso-Neoproterozoic arc-related sediments of the Xiahe Group in the Qinling block, central China: Implications for the paleogeographic reconstruction of Rodinia

The Meso-Neoproterozoic Rodinia supercontinent formed a coherent large landmass, which was later dispersed over all current major continents and a number of microcontinents. The Qinling block is a Precambrian continental mass, located in the Qinling orogenic belt, which marks the junction of the North China and South China cratons. In this paper, we present a systematic study of the petrology, whole-rock geochemistry and geochronology of metasedimentary rocks from the Xiahe Group, which is a key unit of the Precambrian basement in the Qinling block, to constrain the paleogeographic reconstruction of Rodinia. The studied metasedimentary rocks have detrital zircon ages of 3054–1082 Ma that peak at 1172 Ma and 1582 Ma. The protoliths of the metasedimentary rocks are mainly shales and wackes with maximum depositional ages from 1147 to 1082 Ma, representing a part of a continental arc-related sedimentary sequence. Combining our results with existing data, we propose that their protoliths constituted a sedimentary series including an older sequence of basement and a younger sequence with depositional ages between 1262 and 840 Ma. The detritus that is older than 1266 Ma was sourced from the continental margin of the Indian craton, which was part of the Columbia supercontinent. There was a Paleo-Mesoproterozoic continental nucleus in the Qinling block that split from the margin of the Indian craton during the breakup of Columbia. The source rocks for the younger detritus were arc magmatic rocks in the Qinling block, which formed in a continental arc by oceanic lithosphere subduction during the assembly of Rodinia. A sequence of oceanic subduction beneath the continental nucleus of the Qinling block (1262–981 Ma), arc-continent collision between the continental nucleus and the Indian craton (981–911 Ma), continuous subduction of oceanic crust beneath the block with formation of a mature volcanic arc (929–833 Ma), and continental rifting (833–774 Ma) during the formation of the Qinling block was identified. The block faced the Neoproterozoic ocean during the assembly of Rodinia, and finally rifted off the supercontinent during its breakup to form an isolated arc terrane

Provenance and Hf isotopic variation of Precambrian detrital zircons from the Qilian Orogenic Belt, NW China: Evidence to the transition from breakup of Columbia to the assembly of Rodinia

The Qilian Orogenic Belt (QOB) in Northwest China consists of three distinct terranes: North Qilian, Central Qilian, and South Qilian, which have experienced complex rifting and converging. Here, we present new U-Pb ages and Hf isotopes of detrital zircons from the Neoproterozoic and Mesoproterozoic sedimentary rocks in the QOB to constrain the tectonic affinity of the different terranes and provide new evidence to the transition from Columbia to Rodinia. Two Mesoproterozoic zircon samples from the North and the Central Qilian display similar age spectra with a dominant population varying from 1.21 Ga to 1.78 Ga. The population show two age peaks at ~1.5 Ga and ~1.75 Ga and have same range of εHf(t) values from −9.1 to +9.8. Except for this population, the rest zircons yield Paleoproterozoic or even older ages with a peak at ~2.45 Ga. These results suggest that the three terranes were once of a united block in the late Mesoproterozoic. The two Neoproterozoic samples from the Central Qilian and the South Qilian both have a main population of ages at 0.85–1.0 Ga and a minor population peaked at ~2.45 Ga. Their zircon εHf(t) values indicated that the source rocks of the main population were dominantly composed of recycled crustal materials. Because of the comparable and homogeneous age patterns and Hf isotopic compositions of Proterozoic detrital zircons, the QOB has a close relationship to South China from Mesoproterozoic to Early Neoproterozoic. Our zircon ages and Hf isotopic data indicate that the juvenile components increased at 1.6–1.2 Ga, which response to an exterior orogen that newly-formed crust has replaced the lower crust possibly triggered by slab retreat or upwelling of asthenosphere materials related to the breakup of Columbia. In contrast, the abundant addition of the reworking materials at 1.2–0.8 Ga reacts to an interior orogen characteristic because continental collision was involved in the convergent of Rodinia. This changing, therefore, was a response to the transition from breakup of Columbia to the assembly of Rodinia.

Late Mesoproterozoic low-P/T–type metamorphism in the North Wulan terrane: Implications for the assembly of Rodinia

AbstractRegional metamorphism provides critical constraints for unravelling lithosphere evolution and geodynamic settings, especially in an orogenic system. Recently, there has been a debate on the Rodinia-forming Tarimian orogeny within the Greater Tarim block in NW China. The North Wulan terrane, involved in the Paleozoic Qilian orogen, was once part of the Greater Tarim block. This investigation of petrography, whole-rock and mineral geochemistry, phase equilibrium modeling, and in situ monazite U-Pb dating of garnetite, pelitic gneiss, and quartz schist samples from the Statherian–Calymmian unit of the North Wulan terrane provides new constraints on the evolutionary history of the Greater Tarim block at the end of the Mesoproterozoic during the assembly of Rodinia. The studied samples yielded three monazite U-Pb age groups of ca. 1.32 Ga, 1.1 Ga, and 0.45 Ga that are interpreted to be metamorphic in origin. The tectonic significance of the early ca. 1.32 Ga metamorphism is uncertain and may indicate an extensional setting associated with the final breakup of Columbia. The ca. 1.1 Ga low-pressure, high-temperature (low-P/T)–type granulite-facies metamorphism is well preserved and characterized by a clockwise P-T path with a minimum estimation of ∼840–900 °C and ∼7–11 kbar for peak metamorphism, followed by postpeak decompression and cooling. A tectonothermal disturbance occurred at ca. 0.45 Ga, but with limited influence on the preexisting mineral compositions of the studied samples. The characteristics of the metamorphism indicate an arc–back-arc environment with ongoing subduction of oceanic lithosphere at ca. 1.1 Ga. Combined with previous studies, we suggest that the Greater Tarim block probably experienced a prolonged subduction-to-collision process at ca. 1.1–0.9 Ga during the assembly of Rodinia, with a position between western Laurentia and India–East Antarctica.

Pre-Neoproterozoic continental growth of the Yangtze Block: From continental rifting to subduction–accretion

The Yangtze Block exemplifies the gradual formation of cratons since the Archean, and its pre-Neoproterozoic basement constitution needs to be clarified by a study of the combination of spatiotemporal relationship, geochemistry, and radiogenic isotopes of pre-Neoproterozoic rocks within and around the continent. It is suggested that the Yangtze Block could be divided into the north (NYB) and south (SYB) parts before the Neoproterozoic due to distinct rock configuration and tectonic evolution. The NYB consists of extensive Archean lithosphere and witnessed nascent stage (~2.0 Ga) of Columbia (Nuna)-assembly tectonics and was less involved in subsequent supercontinent breakup. It was then surrounded by a series of early Neoproterozoic (1.0–0.93 Ga) intra-oceanic accretionary system, which facilitated the tectonic emplacement of ~1.1–0.95 Ga ophiolite suites and the accretion of allochthonous terranes. The SYB, as well as the south Qinling Orogenic Belt and western Cathaysia Block, in part or in whole, may serve as one of the accretionary terranes around the NYB. These accreted terranes were generally involved in the extensional tectonics in response to the breakup of Columbia supercontinent, with the post-1.5 Ga rift locally evolved to seafloor spreading as evidenced by the occurrences of relic oceanic lithosphere in some areas. We highlight the progressive continental growth from a large-scale, long-term continental rifting during Columbia breakup to subsequent Rodinia-assembly-related tectonics around the NYB. The former stage is characterized by the consuming of ancient continental lithosphere and creation of thick, juvenile volcanic-sedimentary rocks within continents (failed rift) or along passive margins (successful rift). In contrast, the latter stage may have driven the subduction–accretion of allochthonous rift terranes around the NYB and promoted the emplacement of circum-NYB 1.1–0.9 Ga ophiolite suites and island-arc units. We suggest that the significant mantle input in both extension and convergence stages and the successive lateral accretion of terranes may have contributed to the continental growth and reshaping of the Yangtze Block.

Geoquímica dos diques máficos da região leste da Província Aurífera Alta Floresta: inferências sobre a fonte mantélica e implicações geodinâmicas

O enxame de diques máficos de Peixoto de Azevedo e Nova Guarita, região Leste da Província Aurífera Alta Floresta (PAAF), compõe-se de basaltos toleíticos evoluídos. Tais rochas provêm de fonte enriquecida por fluidos originados durante a subducção de crosta oceânica recoberta por significativa quantidade de sedimentos de composição semelhante à média global de sedimentos subductados (global subducting sediment composition — GLOSS). O enxame de diques intrude granitos e gnaisses paleoproterozoicos dos arcos magmáticos Cuiú-Cuiú e Juruena, e possui idade de 1419 Ma. No Cráton Amazônico, suas características geoquímicas relacionadas à sua origem mantélica são muito semelhantes às dos diques máficos de Carajás e da Suíte Máfica Vespor, ambos paleoproterozoicos. São semelhantes em idade quando comparados aos diques de Nova Lacerda, assim como de outras regiões do Supercontinente Columbia, como os diques Bas Drâa Inlier, a W do Cráton da África, a soleira Midsommerso, a NE da Groenlândia, e os diques Michael Gabbro, na Província Grenville, no Canadá. Essas intrusões ocorreram entre 1,42 e 1,33 Ga, durante as fases finais de fragmentação do Supercontinente Columbia.

Ca. 1.7 Ga Magmatism on Southwestern Margin of the Yangtze Block: Response to the Breakup of Columbia

AbstractThis paper presents some data of the Jiaopingdu gabbro and Caiyuanzi granite at the southwestern margin of the Yangtze Block, on the geochemical compositions, zircon LA–ICP–MS U–Pb ages and Hf isotopic data. The Jiaopingdu gabbro gives the age of 1721 ± 5 Ma, the Caiyuanzi granite 1732 ± 6 Ma and 1735 ± 4 Ma, and the Wenjiacun porphyry granite 1713 ± 4 Ma, suggesting nearly contemporaneous formation time of the gabbro and granite. The bimodal feature is demonstrated by the gabbro SiO2content of 44.64–46.87 wt% and granite 73.81–77.03 wt%. In addition, the granite has high content of SiO2and Na2O + K2O, low content of Al2O3and CaO, enriched in REEs (except Eu) and Zr, Nb, Ga and Y, depleted in Sr, implying it belongs to A‐type granite geochemistry and origin of within‐plate environment. The zircon∊Hf(t) of the granite and gabbro is at the range of 2–6, which is near the 2.0 Ga evolution line of the crust, implying the parent magma of the gabbro being derived from the depleted mantle and a small amount of crustal material, and the parent magma of the granite from partial melting of the juvenile crust and some ancient crustal material at the same time. Compared with 1.8–1.7 Ga magmatism during breakup of other cratons in the world, we can deduce that the Columbia has initially broken sinceca. 1.8 Ga, and some continental marginal or intra‐continental rifts occurred atca. 1.73 Ga.

Revisiting to the Neoproterozoic tectonic evolution of the Tarim Block, NW China

The Tarim Block comprises two terranes, namely, the Northern Tarim terrane (NTT) and the Southern Tarim terrane (STT). The distinct geological features of the Pre- Cryogenian basement and igneous activity between these two terranes that share common Cryogenian cover sequences strongly suggest that they underwent independent pre-Cryogenian evolutions. However, owing to the likely position of the Tarim Block on the margin of Rodinia, the Neoproterozoic igneous rocks and sedimentary sequences of this block should provide important insights into the geodynamics of the evolution of this supercontinent. In this contribution, our new geochronological data show that the earliest glacial deposit in the Tarim Block, namely, the Beiyixi tillite, was deposited a little later than 720 Ma, which is consistent with the timing of the global Sturtian glaciation. The other two glacial deposits, namely, the Altungol–Tereenken and Hankachocugh tillites, were deposited at 685–635 Ma and later than 591 Ma, consistent with the global Marinoan and Gaskiers glaciations, respectively.Combining our field observations and new geochronological data with a comprehensive synthesis of the Precambrian basement rock units, metamorphic events, and igneous activities in both the NTT and STT, we construct a detailed late Mesoproterozoic to Cryogenian evolution for the Tarim Block, and discuss its relationship to Precambrian supercontinent evolution. We suggest that the STT might be a continental fragment that separated and drifted from the Congo Craton during the initial breakup of Rodinia and subsequently docked along the northern fringe of Australia a little later than ca. 800 Ma. In contrast, the NTT might be a continental fragment that detached and drifted from North China–India during the breakup of the Columbia supercontinent. During the process of breakup of Columbia and the assembly of Rodinia, the NTT amalgamated with the STT a little earlier than 800 Ma, owing to circum-Rodinia subduction between 1000 and 760 Ma. However, upwelling of the Rodinia plume could have affected subduction along the northern margin of the Tarim Block, as demonstrated by a voluminous ca. 770 Ma mafic dyke swarm. The Rodinia plume terminated the subduction along the northern margin of the Tarim Block at ca. 740 Ma, suggesting that the plume could have played a key role in the breakup of Rodinia. This conclusion is supported by Cryogenian–Cambrian sedimentary sequences with passive-continental-margin affinity in the Tarim Block, indicating the detachment and movement of this block from Rodinia. Both the characteristics of Cryogenian–Cambrian basins and coeval igneous activity argue strongly against long-term subduction along the northern margin of the Tarim Block.

Paleoproterozoic tectonic evolution of the northern Yangtze craton from oceanic subduction through continental collision to continental rifting: Geochronological and geochemical records of metabasites from the Tongbai orogen in central China

We report for the first time the existence of multistage Paleoproterozoic collision- and rift-related tectonothermal events in the northern margin of the Yangtze craton. This is achieved through an integrated study of geochronology and geochemistry for Phanerozoic metabasites from the Tongbai orogen in central China. Zircon U-Pb dating and trace element analysis reveal two episodes of magmatism and one episode of metamorphism from ca. 1.96 Ga to 1.63 Ga. Whole-rock geochemistry indicates that the 1.96 Ga metabasite shows typical arc-like trace elemental distribution patterns with enrichment in LREE but depletion in HFSE, whereas the 1.63 Ga metabasites are characterized by enriched mid-ocean ridge basalts (MORB)- or ocean island basalts (OIB)-like trace element distribution patterns with enrichment in LREE but no depletion in HFSE. In addition, a 1.84 Ga granulite facies metamorphic event is recorded by sector zoned domains of zircon from the 1.96 Ga metabasites, showing flat HREE patterns with markedly negative Eu anomalies and a high formation temperature of 825 °C. Integrating the available data from the northern Yangtze craton, we suggest that the 1.96 Ga metabasite was produced by decompressional melting of the metasomatic mantle domain subsequent to exhumation of the high-pressure metamorphic rocks, the 1.84 Ga granulite facies metamorphism was induced by asthenospheric upwelling in response to post-collisional extension, and the 1.63 Ga magmatism was associated with lithospheric extension due to continental rifting. Therefore, the Paleoproterozoic metabasites in the Tongbai orogen witness the tectonic evolution from oceanic subduction through continental collision to continental rifting, indicating that the northern margin of the Yangtze craton was involved in the assembly and breakup of supercontinent Columbia. In comparison to the coeval rift-related igneous rocks in other blocks, the geochemical features of 1.63 Ga metabasites in the northern Yangtze craton are similar to those in the northern Australia, but are significantly different from those in the southern Siberia and the northern Laurentia. This indicates a possible connection between the northern Yangtze and the northern Australia before the Columbia breakup.

New insights into the Precambrian tectonic evolution and continental affinity of the Qilian block: Evidence from geochronology and geochemistry of metasupracrustal rocks in the North Wulan terrane

Abstract The Qilian block, one of the Precambrian terranes in the Qinling-Qilian-Kunlun orogenic system, is a critical region for reconstruction of the overall architecture and tectonic evolution of NW China. This investigation of zircon U-Pb and Lu-Hf isotopes and whole-rock geochemistry of a metasupracrustal sequence in the North Wulan terrane provides new insights into the Qilian block. A Statherian–Calymmian unit (ca. 1.67–1.5 Ga), dominated by Al- and Si-rich gneisses, arkosites, quartzites, and amphibolites with minor calc-silicate rocks and marbles, is interpreted to have been deposited during continental rifting. Detrital zircons show two main age populations of 2685–2276 and 2098–1761 Ma with mostly negative εHf(t) values (–14.0 to +3.6). The sources are characterized by mixed felsic to intermediate igneous rocks as well as recycled components and are interpreted as being derived from the Tarim craton because of the age distribution of their detrital zircons. A Stenian–Tonian unit (ca. 1.1–0.9 Ga) consists mainly of felsic gneisses, quartzites, calc-silicate rocks, marbles, metavolcanic rocks, and amphibolites. The metasedimentary rocks yielded detrital zircon ages clustering at ca. 1.64, 1.43, 1.3–1.2, 1.1, and 0.94 Ga with predominantly positive εHf(t) values (–7.1 to +9.7). One metavolcanic rock has an age of ca. 1110 Ma and εHf(t) values of +6.5 to +9.1. The provenance is dominated by local syndepositional arc-related igneous rocks with older detritus possibly from Laurentia, again based on the age distribution of the detrital zircons. The Central Qilian and Hualong terranes show strong affinities with the North Wulan terrane and together constituted a single coherent Qilian block prior to their involvement in the Qilian–North Qaidam orogen. The Qilian block was probably once part of the Tarim craton and had a strong linkage to South Tarim, which drifted from North Tarim during the breakup of Columbia in the early Mesoproterozoic. We suggest that, from the late Mesoproterozoic to early Neoproterozoic, the South Tarim–Qilian formed an active continental margin located close to Laurentia during the assembly of Rodinia. The final collision occurred in the early Neoproterozoic with the formation of a significant continent that included the reunified Tarim-Qilian as well as Qaidam-Kunlun and Qinling terranes, Alxa block, Kyrgyz-Chinese Tianshan, and Yili block.

The Paleoproterozoic bimodal magmatism in the SW Yangtze block: Implications for initial breakup of the Columbia supercontinent

The fragmentation of the Columbia supercontinent is thought to have begun as early as ~1.7 Ga; however, the breakup of its core domain occurred only at ~1.5–1.25 Ga. This study presents the integrated petrological and chemical characteristics of gabbro and granite porphyry intrusions in the Haizi region of China, which record the oldest magmatism associated with the initial breakup of Columbia in the southwestern Yangtze Block. The dating of gabbro and granite porphyry samples using laser ablation–inductively coupled plasma–mass spectrometry zircon UPb geochronology gives crystallization ages of 1754 ± 14 Ma and 1743 ± 4 Ma, respectively. The gabbro is characterized by low La/Ta, Th/Y, (La/Yb)N, and (Dy/Yb)N ratios, negligible NbTa anomalies, moderately depleted Nd isotope signatures (εNd (t) = +2.4 to +5.3), and enriched zircon Hf isotopes (εHf(t) = −1.8 to −7.8), indicating derivation of the primary magma from ambient asthenospheric mantle and complex petrogenetic processes before emplacement. Geochemical modeling indicates a variable but low degree of partial melting (1%–15%) and minor crustal contamination during magma ascent. The gabbro samples have relatively high TiO2 (1.94–3.73 wt%) and Zr (95–271 ppm) contents, typical of rocks formed in an intraplate tectonic setting. The granite porphyry samples display high FeOT/MgO and Ga/Al ratios, high contents of high-field-strength elements, and low CaO–Sr contents, resembling A-type granites. Compared with the gabbros, these porphyries show wider geochemical gaps, more variable ratios between incompatible elements, and lower radiogenic Nd isotopic compositions (εNd(t) = +0.3 to +2.7 and TDM2(Nd) = 2226– 2028 Ma). However, the porphyries have more radiogenic zircon Hf isotopes (εHf(t) = 0 to +3.7 and TDM2(Hf) = 2421–2189 Ma) than those of the gabbros, suggesting their derivation from the partial melting of a Paleoproterozoic crustal source triggered by an upwelling basaltic magma in an intraplate extensional setting. The ~1.75 Ga bimodal magmatism reported in this study, together with the ~1.75–1.65 Ga mafic magmatism documented in other cratonic blocks, suggests a possible spatial linkage between the Yangtze Block, northern Australia, northwestern Laurentia, and southern Siberia in the late Paleoproterozoic Columbia supercontinent.

Petrology and geochemistry of the Mesoproterozoic Vattikod lamproites, Eastern Dharwar Craton, southern India: evidence for multiple enrichment of sub-continental lithospheric mantle and links with amalgamation and break-up of the Columbia supercontinent

Numerous lamproite dykes are hosted by the Eastern Dharwar Craton, southern India, particularly towards the northwestern margin of the Cuddapah Basin. We present here a comprehensive mineralogical and geochemical (including Sr and Nd isotopic) study on the lamproites from the Vattikod Field, exposed in the vicinity of the well-studied Ramadugu lamproite field. The Vattikod lamproites trend WNW–ESE to NW–SE and reveal effects of low-temperature post-magmatic alteration. The studied lamproites show porphyritic texture with carbonated and serpentinized olivine, diopside, fluorine-rich phlogopite, amphibole, apatite, chromite, allanite, and calcite. The trace-element geochemistry (elevated Sr and HFSE) reveals their mixed affinity to orogenic as well as anorogenic lamproites. Higher fluorine content of the hydrous phases coupled with higher whole-rock K2O highlights the role of metasomatic phlogopite and apatite in the mantle source regions. Trace-element ratios such as Zr/Hf and Ti/Eu reveal carbonate metasomatism of mantle previously enriched by ancient subduction processes. The initial 87Sr/86Sr-isotopic ratios (calculated for an assumed emplacement age of 1350 Ma) vary from 0.7037 to 0.7087 and ɛNd range from − 10.6 to − 9.3, consistent with data on global lamproites and ultrapotassic rocks. We attribute the mixed orogenic–anorogenic character for the lamproites under study to multi-stage metasomatism. We relate the (1) earlier subduction-related enrichment to the Paleoproterozoic amalgamation of the Columbia supercontinent and the (2) second episode of carbonate metasomatism to the Mesoproterozoic rift-related asthenospheric upwelling associated with the Columbia breakup. This study highlights the association of lamproites with supercontinent amalgamation and fragmentation in the Earth history.

U-Pb zircon and titanite ages from granulites of the Koraput area – Evidence for Columbia, Rodinia and Gondwana from the Eastern Ghats Province, India

The Eastern Ghats Province (EGP) of India, characterized by ∼1 Ga granulite metamorphism (M1), collided with the Archaean Indian craton in either Grenvillian (∼1 Ga) or Pan-African (∼0.6–0.5 Ga) time. At ∼850 Ma, the Koraput Alkaline Complex (KAC) intruded into M1 EGP granulites, and was metamorphosed during a second granulite event (M2) in the EGP. U-Pb zircon dates from gneisses in Koraput yield magmatic ages ∼1500 Ma, with overgrowths at 1100–900 Ma and 800–700 Ma. Cratonic zircons from the EGP contact zone have Archaean 2.8–2.6 Ga cores with overgrowths at ∼700 Ma. Titanites from a calc-silicate gneiss within the EGP define a U-Pb isochron around 700 Ma, whereas titanites from nepheline syenites within the KAC yielded a range of dates from ∼622 to 520 Ma. The c. 1500 Ma age in the EGP either implies Columbia break-up or proximity to a Columbia margin. The ∼700 Ma age is interpreted as the age of M2 granulite metamorphism that followed intracontinental thrusting of the EGP over ∼2.8 Ga granulites of the Jeypore Province. The ∼520 Ma titanite ages are correlated with final juxtaposition of the EGP-Jeypore Province amalgam with the Indian craton during Gondwana formation.