Columbia(Nuna)is a Paleo-Mesoproterozoic supercontinent that was assembled during global 2.0–1.8Ga collisional events,underwent long-lived,subductionrelated accretion at key continental margins in the period
The evolution of Earth's biosphere,atmosphere and hydrosphere is tied to the formation of continental crust and its subsequent movements on tectonic plates.The supercontinent cycle posits that the continental crust i...The evolution of Earth's biosphere,atmosphere and hydrosphere is tied to the formation of continental crust and its subsequent movements on tectonic plates.The supercontinent cycle posits that the continental crust is periodically amalgamated into a single landmass,subsequently breaking up and dispersing into various continental fragments.Columbia is possibly the first true supercontinent,it amalgamated during the 2.0-1.7 Ga period,and collisional orogenesis resulting from its formation peaked at 1.95-1.85 Ga.Geological and palaeomagnetic evidence indicate that Columbia remained as a quasi-integral continental lid until at least 1.3 Ga.Numerous break-up attempts are evidenced by dyke swarms with a large temporal and spatial range; however,palaeomagnetic and geologic evidence suggest these attempts remained unsuccessful.Rather than dispersing into continental fragments,the Columbia supercontinent underwent only minor modifications to form the next supercontinent (Rodinia) at 1.1 -0.9 Ga; these included the transformation of external accretionary belts into the internal Grenville and equivalent collisional belts.Although Columbia provides evidence for a form of ‘lid tectonics’,modern style plate tectonics occurred on its periphery in the form of accretionary orogens.The detrital zircon and preserved geological record are compatible with an increase in the volume of continental crust during Columbia's lifespan; this is a consequence of the continuous accretionary processes along its margins.The quiescence in plate tectonic movements during Columbia's lifespan is correlative with a long period of stability in Earth's atmospheric and oceanic chemistry.Increased variability starting at 1.3 Ga in the environmental record coincides with the transformation of Columbia to Rodinia; thus,the link between plate tectonics and environmental change is strengthened with this interpretation of supercontinent history.展开更多
The volcanic rocks of the Xiong’er Group are situated in the southern margin of the North China Craton(NCC).Research on the Xiong er Group is important to understand the tectonic evolution of the NCC and the Columbia...The volcanic rocks of the Xiong’er Group are situated in the southern margin of the North China Craton(NCC).Research on the Xiong er Group is important to understand the tectonic evolution of the NCC and the Columbia supercontinent during the Paleoproterozoic.In this study,to constrain the age of the Xiong’er volcanic rocks and identify its tectonic environment,we report zircon LA-ICP-MS data with Hf isotope,whole-rock major and trace element compositions and Sr-Nd-Pb-Hf isotopes of the volcanic rocks of the Xiong’er Group.The Xiong’er volcanic rocks mainly consist of basaltic andesite,andesite.dacite and rhyolite,with minor basalt.Our new sets of data combined with those from previous studies indicate that Xiong’er volcanism should have lasted from 1827 Ma to 1746 Ma as the major phase of the volcanism.These volcanics have extremely low MgO.Cr and Ni contents,are enriched in LREEs and LILEs but depleted in HFSEs(Nb,Ta,and Ti),similar to arc-related volcanic rocks.They are characterized by negative zirconεHft values of-17.4 to 8.8,whole-rock initial 87Sr/86Sr values of 0.7023 to 0.7177 andεNd(t)values of-10.9 to 6.4.and Pb isotopes(206Pb/204Pb=14.366-16.431,207Pb/204Pb=15.106-15.371,208Pb/204Pb=32.455-37.422).The available elemental and Sr-Nd-Pb-Hf isotope data suggest that the Xiong’er volcanic rocks were sourced from a mantle contaminated by continental crust.The volcanic rocks of the Xiong’er Group might have been generated by high-degree partial melting of a lithospheric mantle that was originally modified by oceanic subduction in the Archean.Thus,we suggest that the subduction-modified lithospheric mantle occurred in an extensional setting during the breakup of the Columbia supercontinent in the Late Paleoproterozoic,rather than in an arc setting.展开更多
Diverse models have been proposed for the role of the Tarim Craton within the Paleoproterozoic Columbia supercontinent assembly. Here we report a suite of-1.71 Ga Nb-enriched meta-gabbro lenses in the eastern Quanji M...Diverse models have been proposed for the role of the Tarim Craton within the Paleoproterozoic Columbia supercontinent assembly. Here we report a suite of-1.71 Ga Nb-enriched meta-gabbro lenses in the eastern Quanji Massif, within the Tarim Craton in NW China. The meta-gabbroic rocks have Nb contents of 11.5-16.4 ppm with Nb/La ratios varying from 0.84 to 1.02((Nb/La)_N = 0.81-0.98) and Nb/U ratios from 38.0 to 47.2. They show low SiO_2(45.1-48.5 wt.%) and MgO(5.96-6.81 wt.%) and Mg#(Mg# = Mg/(Mg + Fe) = 43.5-47.7), high FeO^t(13.0-15.7 wt.%) and moderate Ti02(1.70-2.51 wt.%).with tholeiitic affinities. These rocks possess low fractionated REE patterns without obvious Eu anomalies(Eu/Eu~* = 0.87-1.02). Their primitive mantle-normalized elements patterns display significant Zr-Hf troughs, positive Nb anomalies, weak negative Ti and P anomalies, and high contents of Rb and Ba,resembling Nb-enriched basalts generated in arc-related tectonic settings. Their arc-like geochemical signatures together with whole rock εNd(t) values of 0.4-2.1 and corresponding old T_(DM)(2.22-2.37 Ga)as well as(^(143)Nd/^(144)Nd)_t and(^(87)Sr/^(86)Sr)t(t = 1712 Ma) values of 0.5104-0.5105 and 0.7030-0.7058,respectively, suggest that their precursor magma originated from mantle wedge peridotite metasomatised by subduction-derived melts. The results from our study reveal subduction along the eastern periphery of the Tarim Craton and marginal outgrowth continuing to ~1.7 Ga within the Columbia supercontinent.展开更多
Objective Petrogenesis of the Paleoproterozoic mafic dikes and their tectonic implications are of great significance to the tectonic evolution of the Yangtze craton as well as the paleoposition of the Yangtze craton r...Objective Petrogenesis of the Paleoproterozoic mafic dikes and their tectonic implications are of great significance to the tectonic evolution of the Yangtze craton as well as the paleoposition of the Yangtze craton relative to the Columbia supercontinent.Till now,展开更多
Steady decline in the percentage of 235U in terrestrial uranium made natural fission impos- sible after about 1.8 Ga. Fission before 1.8 Ga disturbed the lead isotope system at various places world- wide, such as Oklo...Steady decline in the percentage of 235U in terrestrial uranium made natural fission impos- sible after about 1.8 Ga. Fission before 1.8 Ga disturbed the lead isotope system at various places world- wide, such as Oklo, Gabon, and may have caused the first lead isotope paradox. Fission in areas of high uranium concentration may also have generated enough heat to localize sparse Archean and Paleoproter- ozoic UHT belts. The oldest widespread orogenic systems formed at approximately 2.0-1.8 Ga after fission stopped contributing to the earth's heat flow. These early orogenic systems partly created the supercontinent Columbia.展开更多
在Columbia超大陆的聚合和裂解过程中,扬子板块西南缘扮演着重要角色,前人认为Columbia超大陆在古元古代末期—中元古代中期裂解,对于其最初裂解在扬子板块西南缘的响应时间存在~1.85 Ga及~1.75 Ga两种认识(Liu Kang et al.,2019;刘军平...在Columbia超大陆的聚合和裂解过程中,扬子板块西南缘扮演着重要角色,前人认为Columbia超大陆在古元古代末期—中元古代中期裂解,对于其最初裂解在扬子板块西南缘的响应时间存在~1.85 Ga及~1.75 Ga两种认识(Liu Kang et al.,2019;刘军平等,2020)。扬子板块西南缘广泛分布的古元古代1.77~1.65 Ga板内镁铁质岩浆活动代表着超大陆裂解的高峰,而古元古代双峰式岩浆作用则相对罕见。展开更多
The mechanism of the breakup of supercontinent is a scientific frontier in the field of supercontinent study.The rifting and breakup of supercontinent has long been considered to be related to mantle plume.Paleo-
The number of good quality paleomagnetic data of the Mesoproterozoic supercontinent Nuna(e.g.Columbia,Hudsonland)has increased in recent years enabling more reliable global continental reconstructions(e.g Hoffman
The observation is made that there are very strong similarities between the supercontinents Columbia, Rodinia and Pangea. If plate tectonics was operating over the past 2.5 billion years of Earth history, and dominate...The observation is made that there are very strong similarities between the supercontinents Columbia, Rodinia and Pangea. If plate tectonics was operating over the past 2.5 billion years of Earth history, and dominated by extroversion and introversion of ocean basins, it would be unusual for three superconti-nents to resemble one another so closely. The term'strange attractor' is applied to landmasses that form a coherent geometry in all three supercontinents. Baltica, Laurentia and Siberia form a group of'strange attractors' as do the elements of East Gondwana (India, Australia, Antarctica, Madagascar). The elements of "West Gondwana" are positioned as a slightly looser amalgam of cratonic blocks in all three super-continents and are referred to as 'spiritual interlopers'. Relatively few landmasses (the South China, North China, Kalahari and perhaps Tarim cratons) are positioned in distinct locations within each of the three supercontinents and these are referred to as'lonely wanderers'. 〈br〉 There may be several explanations for why these supercontinents show such remarkable similarities. One possibility is that modern-style plate tectonics did not begin until the late Neoproterozoic and horizontal motions were restricted and a vertical style of 'lid tectonics' dominated. If motions were limited for most of the Proterozoic, it would explain the remarkable similarities seen in the Columbia and Rodinia supercontinents, but would still require the strange attractors to rift, drift and return to approximately the same geometry within Pangea. 〈br〉 A second possibility is that our views of older supercontinents are shaped by well-known connections documented for the most recent supercontinent, Pangea. It is intriguing that three of the four 'lonely wanderers' (Tarim, North China, South China) did not unite until just before, or slightly after the breakup of Pangea. The fourth'lonely wanderer', the Kalahari (and core Kaapvaal) craton has a somewhat unique Archean-age geology compared to its nearest neighbors in Gondwana, but very similar to that in western Australia.展开更多
The Alto MoxotóTerrane of the Borborema Province presents a wide exposure of Paleoproterozoic crust,but unlike other continental blocks of South America,its orogenic history is strongly obliterated by late Neopro...The Alto MoxotóTerrane of the Borborema Province presents a wide exposure of Paleoproterozoic crust,but unlike other continental blocks of South America,its orogenic history is strongly obliterated by late Neoproterozoic deformation.New isotopic and geochemical studies were conducted in mafic-ultramafic(Fazenda Carmo Suite)and granitic-gneissic rocks(Riacho do Navio Suite)within the terrane.The former present zircon U-Pb crystallization ages at ca.2.13 Ga,whereas Sm-Nd data suggests a juvenile origin via melting of early Paleoproterozoic to Archean peridotitic sources.Geochemical data for these rocks are compatible with tholeiitic magmas with some degree of crustal contamination and trace element distribution points to a continental-arc related setting interpreted as remnants of the early stages of subduction.In contrast,the Riacho do Navio Suite was emplaced at ca.2.08 Ga and has highly negativeεNd(t)values indicating crustal reworking.The suite displays calc-alkali to alkali-calcic and ferroan geochemical signatures compatible with Cordilleran magmas.In addition,trace-element distribution as well as discriminant diagrams suggest that the precursor magmas were generated during the later stages of a continental arc or in a syn-collisional setting.Based on our results,we suggest that the studied units might represent missing pieces of a Paleoproterozoic accretionary orogen that formed the crustal framework of the Alto MoxotóTerrane,and that this represents a block associated with assembly of the Nuna/Columbia supercontinent,which is now largely hidden within the Neoproterozoic orogenic belts of West Gondwana.展开更多
华北克拉通保存有与Columbia超大陆裂解相关的中元古代岩浆记录。本文综述了华北克拉通中元古代A型花岗岩的时空分布、岩石学和地球化学等特征,讨论了各期次A型花岗岩的成因及构造背景,论述了其对华北克拉通中元古代裂解事件的指示意义...华北克拉通保存有与Columbia超大陆裂解相关的中元古代岩浆记录。本文综述了华北克拉通中元古代A型花岗岩的时空分布、岩石学和地球化学等特征,讨论了各期次A型花岗岩的成因及构造背景,论述了其对华北克拉通中元古代裂解事件的指示意义。华北克拉通主要发育4期A型花岗岩:1)~1.78 Ga A型花岗岩主要分布于南缘熊耳裂陷槽和晋陕地区;2)~1.70 Ga A型花岗岩主要分布于北缘渣尔泰—白云鄂博和燕辽裂陷槽;3)~1.60 Ga A型花岗岩主要分布于南缘熊耳裂陷槽;4)~1.32 Ga A型花岗岩主要分布于北缘渣尔泰—白云鄂博和燕辽裂陷槽。这4期A型花岗岩均来源于地壳物质的部分熔融,可能与同期伸展作用导致岩浆底侵提供热源有关。整体具有造山后伸展到陆内裂谷环境的演化序列,且存在明显的时空差异。华北克拉通中元古代A型花岗岩记录了4期主要的裂解事件,为华北克拉通参与了Columbia超大陆裂解提供了依据。展开更多
文摘Columbia(Nuna)is a Paleo-Mesoproterozoic supercontinent that was assembled during global 2.0–1.8Ga collisional events,underwent long-lived,subductionrelated accretion at key continental margins in the period
文摘The evolution of Earth's biosphere,atmosphere and hydrosphere is tied to the formation of continental crust and its subsequent movements on tectonic plates.The supercontinent cycle posits that the continental crust is periodically amalgamated into a single landmass,subsequently breaking up and dispersing into various continental fragments.Columbia is possibly the first true supercontinent,it amalgamated during the 2.0-1.7 Ga period,and collisional orogenesis resulting from its formation peaked at 1.95-1.85 Ga.Geological and palaeomagnetic evidence indicate that Columbia remained as a quasi-integral continental lid until at least 1.3 Ga.Numerous break-up attempts are evidenced by dyke swarms with a large temporal and spatial range; however,palaeomagnetic and geologic evidence suggest these attempts remained unsuccessful.Rather than dispersing into continental fragments,the Columbia supercontinent underwent only minor modifications to form the next supercontinent (Rodinia) at 1.1 -0.9 Ga; these included the transformation of external accretionary belts into the internal Grenville and equivalent collisional belts.Although Columbia provides evidence for a form of ‘lid tectonics’,modern style plate tectonics occurred on its periphery in the form of accretionary orogens.The detrital zircon and preserved geological record are compatible with an increase in the volume of continental crust during Columbia's lifespan; this is a consequence of the continuous accretionary processes along its margins.The quiescence in plate tectonic movements during Columbia's lifespan is correlative with a long period of stability in Earth's atmospheric and oceanic chemistry.Increased variability starting at 1.3 Ga in the environmental record coincides with the transformation of Columbia to Rodinia; thus,the link between plate tectonics and environmental change is strengthened with this interpretation of supercontinent history.
基金supported by the National Natural Science Foundation of China(Grant No.41872080)the National Basic Research Program of China(Grant No.2015CB452603)+1 种基金the MOST Special Fund from the State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences(Beijing)(Grant No.MSFGPMR201804)and the Fundamental Research Funds for the Central Universities of China(Grant Nos.2652016077,2652017223)
文摘The volcanic rocks of the Xiong’er Group are situated in the southern margin of the North China Craton(NCC).Research on the Xiong er Group is important to understand the tectonic evolution of the NCC and the Columbia supercontinent during the Paleoproterozoic.In this study,to constrain the age of the Xiong’er volcanic rocks and identify its tectonic environment,we report zircon LA-ICP-MS data with Hf isotope,whole-rock major and trace element compositions and Sr-Nd-Pb-Hf isotopes of the volcanic rocks of the Xiong’er Group.The Xiong’er volcanic rocks mainly consist of basaltic andesite,andesite.dacite and rhyolite,with minor basalt.Our new sets of data combined with those from previous studies indicate that Xiong’er volcanism should have lasted from 1827 Ma to 1746 Ma as the major phase of the volcanism.These volcanics have extremely low MgO.Cr and Ni contents,are enriched in LREEs and LILEs but depleted in HFSEs(Nb,Ta,and Ti),similar to arc-related volcanic rocks.They are characterized by negative zirconεHft values of-17.4 to 8.8,whole-rock initial 87Sr/86Sr values of 0.7023 to 0.7177 andεNd(t)values of-10.9 to 6.4.and Pb isotopes(206Pb/204Pb=14.366-16.431,207Pb/204Pb=15.106-15.371,208Pb/204Pb=32.455-37.422).The available elemental and Sr-Nd-Pb-Hf isotope data suggest that the Xiong’er volcanic rocks were sourced from a mantle contaminated by continental crust.The volcanic rocks of the Xiong’er Group might have been generated by high-degree partial melting of a lithospheric mantle that was originally modified by oceanic subduction in the Archean.Thus,we suggest that the subduction-modified lithospheric mantle occurred in an extensional setting during the breakup of the Columbia supercontinent in the Late Paleoproterozoic,rather than in an arc setting.
基金supported by the National Science Foundation of ChinaNSFC grants(Grant Nos.41602056,41372075,41172069)+1 种基金the China Postdoctoral Science Foundation(Grant No.2016M590729)the Fundamental Research Funds for National Universities,China University of Geosciences(Wuhan)(Grant No.CUG160846)
文摘Diverse models have been proposed for the role of the Tarim Craton within the Paleoproterozoic Columbia supercontinent assembly. Here we report a suite of-1.71 Ga Nb-enriched meta-gabbro lenses in the eastern Quanji Massif, within the Tarim Craton in NW China. The meta-gabbroic rocks have Nb contents of 11.5-16.4 ppm with Nb/La ratios varying from 0.84 to 1.02((Nb/La)_N = 0.81-0.98) and Nb/U ratios from 38.0 to 47.2. They show low SiO_2(45.1-48.5 wt.%) and MgO(5.96-6.81 wt.%) and Mg#(Mg# = Mg/(Mg + Fe) = 43.5-47.7), high FeO^t(13.0-15.7 wt.%) and moderate Ti02(1.70-2.51 wt.%).with tholeiitic affinities. These rocks possess low fractionated REE patterns without obvious Eu anomalies(Eu/Eu~* = 0.87-1.02). Their primitive mantle-normalized elements patterns display significant Zr-Hf troughs, positive Nb anomalies, weak negative Ti and P anomalies, and high contents of Rb and Ba,resembling Nb-enriched basalts generated in arc-related tectonic settings. Their arc-like geochemical signatures together with whole rock εNd(t) values of 0.4-2.1 and corresponding old T_(DM)(2.22-2.37 Ga)as well as(^(143)Nd/^(144)Nd)_t and(^(87)Sr/^(86)Sr)t(t = 1712 Ma) values of 0.5104-0.5105 and 0.7030-0.7058,respectively, suggest that their precursor magma originated from mantle wedge peridotite metasomatised by subduction-derived melts. The results from our study reveal subduction along the eastern periphery of the Tarim Craton and marginal outgrowth continuing to ~1.7 Ga within the Columbia supercontinent.
基金financially supported by National Science Foundation of China(grant No.41303026)the funded project of the China Geological Survey(grants No.DD20160030,DD20160351 and DD20160029)
文摘Objective Petrogenesis of the Paleoproterozoic mafic dikes and their tectonic implications are of great significance to the tectonic evolution of the Yangtze craton as well as the paleoposition of the Yangtze craton relative to the Columbia supercontinent.Till now,
文摘Steady decline in the percentage of 235U in terrestrial uranium made natural fission impos- sible after about 1.8 Ga. Fission before 1.8 Ga disturbed the lead isotope system at various places world- wide, such as Oklo, Gabon, and may have caused the first lead isotope paradox. Fission in areas of high uranium concentration may also have generated enough heat to localize sparse Archean and Paleoproter- ozoic UHT belts. The oldest widespread orogenic systems formed at approximately 2.0-1.8 Ga after fission stopped contributing to the earth's heat flow. These early orogenic systems partly created the supercontinent Columbia.
文摘在Columbia超大陆的聚合和裂解过程中,扬子板块西南缘扮演着重要角色,前人认为Columbia超大陆在古元古代末期—中元古代中期裂解,对于其最初裂解在扬子板块西南缘的响应时间存在~1.85 Ga及~1.75 Ga两种认识(Liu Kang et al.,2019;刘军平等,2020)。扬子板块西南缘广泛分布的古元古代1.77~1.65 Ga板内镁铁质岩浆活动代表着超大陆裂解的高峰,而古元古代双峰式岩浆作用则相对罕见。
文摘The mechanism of the breakup of supercontinent is a scientific frontier in the field of supercontinent study.The rifting and breakup of supercontinent has long been considered to be related to mantle plume.Paleo-
文摘The number of good quality paleomagnetic data of the Mesoproterozoic supercontinent Nuna(e.g.Columbia,Hudsonland)has increased in recent years enabling more reliable global continental reconstructions(e.g Hoffman
基金supported in part by grants from the National Science Foundation EAR09-10888 and EAR11-19038
文摘The observation is made that there are very strong similarities between the supercontinents Columbia, Rodinia and Pangea. If plate tectonics was operating over the past 2.5 billion years of Earth history, and dominated by extroversion and introversion of ocean basins, it would be unusual for three superconti-nents to resemble one another so closely. The term'strange attractor' is applied to landmasses that form a coherent geometry in all three supercontinents. Baltica, Laurentia and Siberia form a group of'strange attractors' as do the elements of East Gondwana (India, Australia, Antarctica, Madagascar). The elements of "West Gondwana" are positioned as a slightly looser amalgam of cratonic blocks in all three super-continents and are referred to as 'spiritual interlopers'. Relatively few landmasses (the South China, North China, Kalahari and perhaps Tarim cratons) are positioned in distinct locations within each of the three supercontinents and these are referred to as'lonely wanderers'. 〈br〉 There may be several explanations for why these supercontinents show such remarkable similarities. One possibility is that modern-style plate tectonics did not begin until the late Neoproterozoic and horizontal motions were restricted and a vertical style of 'lid tectonics' dominated. If motions were limited for most of the Proterozoic, it would explain the remarkable similarities seen in the Columbia and Rodinia supercontinents, but would still require the strange attractors to rift, drift and return to approximately the same geometry within Pangea. 〈br〉 A second possibility is that our views of older supercontinents are shaped by well-known connections documented for the most recent supercontinent, Pangea. It is intriguing that three of the four 'lonely wanderers' (Tarim, North China, South China) did not unite until just before, or slightly after the breakup of Pangea. The fourth'lonely wanderer', the Kalahari (and core Kaapvaal) craton has a somewhat unique Archean-age geology compared to its nearest neighbors in Gondwana, but very similar to that in western Australia.
基金support from Australian Research Council grant FL160100168supported by the National Institute of Science and Technology for Tectonic Studies(INCT)of Brazil。
文摘The Alto MoxotóTerrane of the Borborema Province presents a wide exposure of Paleoproterozoic crust,but unlike other continental blocks of South America,its orogenic history is strongly obliterated by late Neoproterozoic deformation.New isotopic and geochemical studies were conducted in mafic-ultramafic(Fazenda Carmo Suite)and granitic-gneissic rocks(Riacho do Navio Suite)within the terrane.The former present zircon U-Pb crystallization ages at ca.2.13 Ga,whereas Sm-Nd data suggests a juvenile origin via melting of early Paleoproterozoic to Archean peridotitic sources.Geochemical data for these rocks are compatible with tholeiitic magmas with some degree of crustal contamination and trace element distribution points to a continental-arc related setting interpreted as remnants of the early stages of subduction.In contrast,the Riacho do Navio Suite was emplaced at ca.2.08 Ga and has highly negativeεNd(t)values indicating crustal reworking.The suite displays calc-alkali to alkali-calcic and ferroan geochemical signatures compatible with Cordilleran magmas.In addition,trace-element distribution as well as discriminant diagrams suggest that the precursor magmas were generated during the later stages of a continental arc or in a syn-collisional setting.Based on our results,we suggest that the studied units might represent missing pieces of a Paleoproterozoic accretionary orogen that formed the crustal framework of the Alto MoxotóTerrane,and that this represents a block associated with assembly of the Nuna/Columbia supercontinent,which is now largely hidden within the Neoproterozoic orogenic belts of West Gondwana.
文摘华北克拉通保存有与Columbia超大陆裂解相关的中元古代岩浆记录。本文综述了华北克拉通中元古代A型花岗岩的时空分布、岩石学和地球化学等特征,讨论了各期次A型花岗岩的成因及构造背景,论述了其对华北克拉通中元古代裂解事件的指示意义。华北克拉通主要发育4期A型花岗岩:1)~1.78 Ga A型花岗岩主要分布于南缘熊耳裂陷槽和晋陕地区;2)~1.70 Ga A型花岗岩主要分布于北缘渣尔泰—白云鄂博和燕辽裂陷槽;3)~1.60 Ga A型花岗岩主要分布于南缘熊耳裂陷槽;4)~1.32 Ga A型花岗岩主要分布于北缘渣尔泰—白云鄂博和燕辽裂陷槽。这4期A型花岗岩均来源于地壳物质的部分熔融,可能与同期伸展作用导致岩浆底侵提供热源有关。整体具有造山后伸展到陆内裂谷环境的演化序列,且存在明显的时空差异。华北克拉通中元古代A型花岗岩记录了4期主要的裂解事件,为华北克拉通参与了Columbia超大陆裂解提供了依据。