Trondhjemite

14,000,000 Leading Edge Experts on the ideXlab platform

Scan Science and Technology

Contact Leading Edge Experts & Companies

Scan Science and Technology

Contact Leading Edge Experts & Companies

The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform

Quyen Minh Nguyen - One of the best experts on this subject based on the ideXlab platform.

  • cambrian intra oceanic arc Trondhjemite and tonalite in the tam ky phuoc son suture zone central vietnam implications for the early paleozoic assembly of the indochina block
    Gondwana Research, 2019
    Co-Authors: Quyen Minh Nguyen, Qinglai Feng, Jianwei Zi, Tianyu Zhao, Hai Thanh Tran, Dung My Tran, Hung Quoc Nguyen
    Abstract:

    Abstract The Truong Son and Kon Tum terranes in northeastern Indochina are thought to, respectively, form part of the Indian and Australian margins of Gondwana and separated one another by the Tam Ky–Phuoc Son Ocean during the early Paleozoic. In this paper, we present results of a comprehensive geochronological and geochemical study on a Trondhjemitetonalite suite identified in the Tam Ky–Phuoc Son Suture Zone. LA–ICP–MS zircon U–Pb dating yielded weighted mean 206Pb/238U ages of 518.5 ± 7.1 Ma and 502.1 ± 6.0 Ma for the Trondhjemite and tonalite, respectively. These are the oldest magmatic zircons recorded in this area so far. Both rocks consist primarily of plagioclase (oligoclase), quartz, with minor, variable amounts of hornblende and biotite. They have high SiO2, Na2O and Y, but low Al2O3, K2O, Sr and Rb contents, and are characterized by depletion in LREEs with flat HREE patterns. These features are similar to those of typical oceanic plagiogranites. Our new evidences from field geology, geochemistry, and zircon Hf isotopic data, along with previously published data from the Tam Ky–Phuoc Son Suture Zone, suggest that the plagiogranites were originated from extensive fractionation of hydrous basaltic magmas. Furthermore, they were generated in an intra-oceanic arc system above a northward subduction zone within the Tam Ky–Phuoc Son Ocean. The final closure of this ocean took place before the late Silurian, marked by collision of the Truong Son Terrane with the Kon Tum Terrane along the Tam Ky–Phuoc Son Suture Zone to form the Indochina Block. After elimination of the southeastward offset along the Red River shear zone and the clockwise rotation of Indochina relative to South China since the Tertiary, the eastern part of the Tam Ky–Phuoc Son Suture aligns well with the Kuungan Suture on Hainan Island, together they have likely recorded the final assembly of Gondwana in this region.

  • Cambrian intra–oceanic arc Trondhjemite and tonalite in the Tam Ky–Phuoc Son Suture Zone, central Vietnam: Implications for the early Paleozoic assembly of the Indochina Block
    Gondwana Research, 2019
    Co-Authors: Quyen Minh Nguyen, Qinglai Feng, Jianwei Zi, Tianyu Zhao, Hai Thanh Tran, Dung My Tran, Hung Quoc Nguyen
    Abstract:

    Abstract The Truong Son and Kon Tum terranes in northeastern Indochina are thought to, respectively, form part of the Indian and Australian margins of Gondwana and separated one another by the Tam Ky–Phuoc Son Ocean during the early Paleozoic. In this paper, we present results of a comprehensive geochronological and geochemical study on a Trondhjemitetonalite suite identified in the Tam Ky–Phuoc Son Suture Zone. LA–ICP–MS zircon U–Pb dating yielded weighted mean 206Pb/238U ages of 518.5 ± 7.1 Ma and 502.1 ± 6.0 Ma for the Trondhjemite and tonalite, respectively. These are the oldest magmatic zircons recorded in this area so far. Both rocks consist primarily of plagioclase (oligoclase), quartz, with minor, variable amounts of hornblende and biotite. They have high SiO2, Na2O and Y, but low Al2O3, K2O, Sr and Rb contents, and are characterized by depletion in LREEs with flat HREE patterns. These features are similar to those of typical oceanic plagiogranites. Our new evidences from field geology, geochemistry, and zircon Hf isotopic data, along with previously published data from the Tam Ky–Phuoc Son Suture Zone, suggest that the plagiogranites were originated from extensive fractionation of hydrous basaltic magmas. Furthermore, they were generated in an intra-oceanic arc system above a northward subduction zone within the Tam Ky–Phuoc Son Ocean. The final closure of this ocean took place before the late Silurian, marked by collision of the Truong Son Terrane with the Kon Tum Terrane along the Tam Ky–Phuoc Son Suture Zone to form the Indochina Block. After elimination of the southeastward offset along the Red River shear zone and the clockwise rotation of Indochina relative to South China since the Tertiary, the eastern part of the Tam Ky–Phuoc Son Suture aligns well with the Kuungan Suture on Hainan Island, together they have likely recorded the final assembly of Gondwana in this region.

Hung Quoc Nguyen - One of the best experts on this subject based on the ideXlab platform.

  • cambrian intra oceanic arc Trondhjemite and tonalite in the tam ky phuoc son suture zone central vietnam implications for the early paleozoic assembly of the indochina block
    Gondwana Research, 2019
    Co-Authors: Quyen Minh Nguyen, Qinglai Feng, Jianwei Zi, Tianyu Zhao, Hai Thanh Tran, Dung My Tran, Hung Quoc Nguyen
    Abstract:

    Abstract The Truong Son and Kon Tum terranes in northeastern Indochina are thought to, respectively, form part of the Indian and Australian margins of Gondwana and separated one another by the Tam Ky–Phuoc Son Ocean during the early Paleozoic. In this paper, we present results of a comprehensive geochronological and geochemical study on a Trondhjemitetonalite suite identified in the Tam Ky–Phuoc Son Suture Zone. LA–ICP–MS zircon U–Pb dating yielded weighted mean 206Pb/238U ages of 518.5 ± 7.1 Ma and 502.1 ± 6.0 Ma for the Trondhjemite and tonalite, respectively. These are the oldest magmatic zircons recorded in this area so far. Both rocks consist primarily of plagioclase (oligoclase), quartz, with minor, variable amounts of hornblende and biotite. They have high SiO2, Na2O and Y, but low Al2O3, K2O, Sr and Rb contents, and are characterized by depletion in LREEs with flat HREE patterns. These features are similar to those of typical oceanic plagiogranites. Our new evidences from field geology, geochemistry, and zircon Hf isotopic data, along with previously published data from the Tam Ky–Phuoc Son Suture Zone, suggest that the plagiogranites were originated from extensive fractionation of hydrous basaltic magmas. Furthermore, they were generated in an intra-oceanic arc system above a northward subduction zone within the Tam Ky–Phuoc Son Ocean. The final closure of this ocean took place before the late Silurian, marked by collision of the Truong Son Terrane with the Kon Tum Terrane along the Tam Ky–Phuoc Son Suture Zone to form the Indochina Block. After elimination of the southeastward offset along the Red River shear zone and the clockwise rotation of Indochina relative to South China since the Tertiary, the eastern part of the Tam Ky–Phuoc Son Suture aligns well with the Kuungan Suture on Hainan Island, together they have likely recorded the final assembly of Gondwana in this region.

  • Cambrian intra–oceanic arc Trondhjemite and tonalite in the Tam Ky–Phuoc Son Suture Zone, central Vietnam: Implications for the early Paleozoic assembly of the Indochina Block
    Gondwana Research, 2019
    Co-Authors: Quyen Minh Nguyen, Qinglai Feng, Jianwei Zi, Tianyu Zhao, Hai Thanh Tran, Dung My Tran, Hung Quoc Nguyen
    Abstract:

    Abstract The Truong Son and Kon Tum terranes in northeastern Indochina are thought to, respectively, form part of the Indian and Australian margins of Gondwana and separated one another by the Tam Ky–Phuoc Son Ocean during the early Paleozoic. In this paper, we present results of a comprehensive geochronological and geochemical study on a Trondhjemitetonalite suite identified in the Tam Ky–Phuoc Son Suture Zone. LA–ICP–MS zircon U–Pb dating yielded weighted mean 206Pb/238U ages of 518.5 ± 7.1 Ma and 502.1 ± 6.0 Ma for the Trondhjemite and tonalite, respectively. These are the oldest magmatic zircons recorded in this area so far. Both rocks consist primarily of plagioclase (oligoclase), quartz, with minor, variable amounts of hornblende and biotite. They have high SiO2, Na2O and Y, but low Al2O3, K2O, Sr and Rb contents, and are characterized by depletion in LREEs with flat HREE patterns. These features are similar to those of typical oceanic plagiogranites. Our new evidences from field geology, geochemistry, and zircon Hf isotopic data, along with previously published data from the Tam Ky–Phuoc Son Suture Zone, suggest that the plagiogranites were originated from extensive fractionation of hydrous basaltic magmas. Furthermore, they were generated in an intra-oceanic arc system above a northward subduction zone within the Tam Ky–Phuoc Son Ocean. The final closure of this ocean took place before the late Silurian, marked by collision of the Truong Son Terrane with the Kon Tum Terrane along the Tam Ky–Phuoc Son Suture Zone to form the Indochina Block. After elimination of the southeastward offset along the Red River shear zone and the clockwise rotation of Indochina relative to South China since the Tertiary, the eastern part of the Tam Ky–Phuoc Son Suture aligns well with the Kuungan Suture on Hainan Island, together they have likely recorded the final assembly of Gondwana in this region.

Jianwei Zi - One of the best experts on this subject based on the ideXlab platform.

  • cambrian intra oceanic arc Trondhjemite and tonalite in the tam ky phuoc son suture zone central vietnam implications for the early paleozoic assembly of the indochina block
    Gondwana Research, 2019
    Co-Authors: Quyen Minh Nguyen, Qinglai Feng, Jianwei Zi, Tianyu Zhao, Hai Thanh Tran, Dung My Tran, Hung Quoc Nguyen
    Abstract:

    Abstract The Truong Son and Kon Tum terranes in northeastern Indochina are thought to, respectively, form part of the Indian and Australian margins of Gondwana and separated one another by the Tam Ky–Phuoc Son Ocean during the early Paleozoic. In this paper, we present results of a comprehensive geochronological and geochemical study on a Trondhjemitetonalite suite identified in the Tam Ky–Phuoc Son Suture Zone. LA–ICP–MS zircon U–Pb dating yielded weighted mean 206Pb/238U ages of 518.5 ± 7.1 Ma and 502.1 ± 6.0 Ma for the Trondhjemite and tonalite, respectively. These are the oldest magmatic zircons recorded in this area so far. Both rocks consist primarily of plagioclase (oligoclase), quartz, with minor, variable amounts of hornblende and biotite. They have high SiO2, Na2O and Y, but low Al2O3, K2O, Sr and Rb contents, and are characterized by depletion in LREEs with flat HREE patterns. These features are similar to those of typical oceanic plagiogranites. Our new evidences from field geology, geochemistry, and zircon Hf isotopic data, along with previously published data from the Tam Ky–Phuoc Son Suture Zone, suggest that the plagiogranites were originated from extensive fractionation of hydrous basaltic magmas. Furthermore, they were generated in an intra-oceanic arc system above a northward subduction zone within the Tam Ky–Phuoc Son Ocean. The final closure of this ocean took place before the late Silurian, marked by collision of the Truong Son Terrane with the Kon Tum Terrane along the Tam Ky–Phuoc Son Suture Zone to form the Indochina Block. After elimination of the southeastward offset along the Red River shear zone and the clockwise rotation of Indochina relative to South China since the Tertiary, the eastern part of the Tam Ky–Phuoc Son Suture aligns well with the Kuungan Suture on Hainan Island, together they have likely recorded the final assembly of Gondwana in this region.

  • Cambrian intra–oceanic arc Trondhjemite and tonalite in the Tam Ky–Phuoc Son Suture Zone, central Vietnam: Implications for the early Paleozoic assembly of the Indochina Block
    Gondwana Research, 2019
    Co-Authors: Quyen Minh Nguyen, Qinglai Feng, Jianwei Zi, Tianyu Zhao, Hai Thanh Tran, Dung My Tran, Hung Quoc Nguyen
    Abstract:

    Abstract The Truong Son and Kon Tum terranes in northeastern Indochina are thought to, respectively, form part of the Indian and Australian margins of Gondwana and separated one another by the Tam Ky–Phuoc Son Ocean during the early Paleozoic. In this paper, we present results of a comprehensive geochronological and geochemical study on a Trondhjemitetonalite suite identified in the Tam Ky–Phuoc Son Suture Zone. LA–ICP–MS zircon U–Pb dating yielded weighted mean 206Pb/238U ages of 518.5 ± 7.1 Ma and 502.1 ± 6.0 Ma for the Trondhjemite and tonalite, respectively. These are the oldest magmatic zircons recorded in this area so far. Both rocks consist primarily of plagioclase (oligoclase), quartz, with minor, variable amounts of hornblende and biotite. They have high SiO2, Na2O and Y, but low Al2O3, K2O, Sr and Rb contents, and are characterized by depletion in LREEs with flat HREE patterns. These features are similar to those of typical oceanic plagiogranites. Our new evidences from field geology, geochemistry, and zircon Hf isotopic data, along with previously published data from the Tam Ky–Phuoc Son Suture Zone, suggest that the plagiogranites were originated from extensive fractionation of hydrous basaltic magmas. Furthermore, they were generated in an intra-oceanic arc system above a northward subduction zone within the Tam Ky–Phuoc Son Ocean. The final closure of this ocean took place before the late Silurian, marked by collision of the Truong Son Terrane with the Kon Tum Terrane along the Tam Ky–Phuoc Son Suture Zone to form the Indochina Block. After elimination of the southeastward offset along the Red River shear zone and the clockwise rotation of Indochina relative to South China since the Tertiary, the eastern part of the Tam Ky–Phuoc Son Suture aligns well with the Kuungan Suture on Hainan Island, together they have likely recorded the final assembly of Gondwana in this region.

Calvin G Barnes - One of the best experts on this subject based on the ideXlab platform.

  • Petrology of iron-rich magmatic segregations associated with strongly peraluminous Trondhjemite in the Cornucopia stock, northeastern Oregon
    Contributions to Mineralogy and Petrology, 2002
    Co-Authors: Kenneth Johnson, Calvin G Barnes, James M Browning, Haraldur R. Karlsson
    Abstract:

    The Middle Cretaceous Cornucopia stock in the Blue Mountains of northeastern Oregon is a small composite intrusion consisting of hornblende biotite tonalite, biotite Trondhjemite, and three cordierite two mica Trondhjemite units. Unusual magnetite + biotite-rich tonalitic rocks are associated with the Crater Lake cordierite Trondhjemite, the youngest of the intrusions. Oxide-rich tonalites are characterized by high Fe (~47–68 wt% total Fe as FeO), low SiO2 (

  • petrology of iron rich magmatic segregations associated with strongly peraluminous Trondhjemite in the cornucopia stock northeastern oregon
    Contributions to Mineralogy and Petrology, 2002
    Co-Authors: Kenneth Johnson, Calvin G Barnes, James M Browning, Haraldur R. Karlsson
    Abstract:

    The Middle Cretaceous Cornucopia stock in the Blue Mountains of northeastern Oregon is a small composite intrusion consisting of hornblende biotite tonalite, biotite Trondhjemite, and three cordierite two mica Trondhjemite units. Unusual magnetite + biotite-rich tonalitic rocks are associated with the Crater Lake cordierite Trondhjemite, the youngest of the intrusions. Oxide-rich tonalites are characterized by high Fe (~47–68 wt% total Fe as FeO), low SiO2 (<36 wt%), and enrichments in HFSE and REE (La(N)=361–903). Oxide-rich tonalites appear in a variety of forms, including composite dikes and sheets, in which they are associated with leucocratic tonalite. Leucotonalite is lower in SiO2 (60–72 wt%) than Crater Lake Trondhjemite, and generally has ΣREE contents and Eu anomalies intermediate between the oxide-rich tonalite and Crater Lake compositions. Oxide-rich tonalites crosscut, and are crosscut by, shear zones in the host Trondhjemite, indicating their emplacement late in the pluton's crystallization history. Granitic dikes crosscut the composite dikes in all localities. Geochemical considerations and sedimentary-like structures, such as load casts and bedding of magnetite-rich assemblages in the composite dikes and sheets, are suggestive of crystal settling from an Fe-rich parental magma. The Fe-rich liquid parental to the oxide-rich tonalite–leucotonalite pairs formed by extensive, in-situ, plagioclase + quartz-dominated crystallization of strongly peraluminous Trondhjemite. Early magnetite saturation in the Trondhjemite was suppressed, either because the parental trondhjemitic magma had a lower initial total Fe content or because it had a lower ferric–ferrous ratio, possibly reflecting a lower oxygen fugacity. Accumulation of magnetite from Fe-rich residual magma is a viable mechanism for the concentration of iron, and the subsequent formation of Fe-rich rocks, in calcic siliceous intrusions. Apparently, Fe-enrichment can occur locally in calcic magmas, and is not restricted to rocks of mafic tholeiitic or anorthositic affinity.

  • Petrology, Geochemistry, and Genesis of High-Al Tonalite and Trondhjemites of the Cornucopia Stock, Blue Mountains, Northeastern Oregon
    Journal of Petrology, 1997
    Co-Authors: Kenneth Johnson, Calvin G Barnes, Christopher A. Miller
    Abstract:

    Tonalitic and trondhjemitic compositions span a narrow range of Trondhjemite SiO2 content (65‐74 wt %) and exhibit characteristics of a highAl tonaliteTrondhjemite‐granitoid (TTG) suite, including light rare earth element (LREE) enrichment, low Y, Nb and Rb/Sr, and high Al2O3 and Sr. These compositions are consistent with an

  • source and tectonic implications of tonalite Trondhjemite magmatism in the klamath mountains
    Contributions to Mineralogy and Petrology, 1996
    Co-Authors: Calvin G Barnes, Ronald W Kistler, Scott W Petersen, Robert Murray, Allan M Kays
    Abstract:

    In the Klamath Mountains, voluminous tonalite-Trondhjemite magmatism was characteristic of a short period of time from about 144 to 136 Ma (Early Cretaceous). It occurred about 5 to 10 m.y. after the ∼165 to 159 Ma Josephine ophiolite was thrust beneath older parts of the province during the Nevadan orogeny (thrusting from ∼155 to 148 Ma). The magmatism also corresponds to a period of slow or no subduction. Most of the plutons crop out in the south-central Klamath Mountains in California, but one occurs in Oregon at the northern end of the province. Compositionally extended members of the suite consist of precursor gabbroic to dioritic rocks followed by later, more voluminous tonalitic and trondhjemitic intrusions. Most plutons consist almost entirely of tonalite and Trondhjemite. Poorly-defined concentric zoning is common. Tonalitic rocks are typically of the low-Al type but Trondhjemites are generally of the high-Al type, even those that occur in the same pluton as low-Al tonalite. The suite is characterized by low abundances of K2O, Rb, Zr, and heavy rare earth elements. Sr contents are generally moderate (∼450 ppm) by comparison with Sr-rich arc lavas interpreted to be slab melts (up to 2000 ppm). Initial 87Sr/86Sr, δ18O, and ɛNd are typical of mantle-derived magmas or of crustally-derived magmas with a metabasic source. Compositional variation within plutons can be modeled by variable degrees of partial melting of a heterogeneous metabasaltic source (transitional mid-ocean ridge to island arc basalt), but not by fractional crystallyzation of a basaltic parent. Melting models require a residual assemblage of clinopyroxene+garnet±plagioclase±amphibole; residual plagioclase suggests a deep crustal origin rather than melting of a subducted slab. Such models are consistent with the metabasic part of the Josephine ophiolite as the source. Because the Josephine ophiolite was at low T during Nevadan thrusting, an external heat source was probably necessary to achieve significant degrees of melting; heat was probably extracted from mantle-derived basaltic melts, which were parental to the mafic precursors of the tonalite-Trondhjemite suite. Thus, under appropriate tectonic and thermal conditions, heterogeneous mafic crustal rocks can melt to form both low- and high-Al tonalitic and trondhjemitic magmas; slab melting is not necessary.

  • geochemistry of peraluminous tonalite and Trondhjemite the cornucopia stock blue mountains ne oregon
    Geological Society of America Abstracts with Programs; (United States), 1993
    Co-Authors: Kenneth Johnson, Calvin G Barnes, Ronald W Kistler
    Abstract:

    The Cretaceous Cornucopia stock was emplaced into a greenschist-facies Permo-Triassic arc terrane. The stock comprises five distinct units: hornblende biotite tonalite, biotite Trondhjemite, and three cordierite biotite Trondhjemites, all with late dacitic and granitic dikes. Tonalite and Trondhjemites span a narrow range of SiO[sub 2] contents and exhibit characteristics of a high-Al tonalite-Trondhjemite-dacite (TTD) suite: LREE enrichment, low Y (< 15 ppm), Nb (< 10 ppm), Rb/Sr ([le]0.04), and high Sr (550--800 ppm). Euhedral cordierite phenocrysts imply the Trondhjemites were H[sub 2]O-rich and were emplaced at pressures of < 2 kbars. Trace element and REE models are consistent with an origin for the tonalite and Trondhjemites by variable degrees (< 40%) of partial melting of a low-K tholeiitic source, with a garnet amphibolite residuum. Individual units are not related by fractional crystallization, but instead represent distinct partial melts. High Sr contents in the TTD rocks, the presence of residual garnet, and abundant residual amphibole implied by partial melting models suggest that melting occurred under H[sub 2]O-rich conditions at P [ge] 8--10 kbars.

Jasper Berndt - One of the best experts on this subject based on the ideXlab platform.

  • magmatic and metamorphic history of paleoarchean tonalite Trondhjemite granodiorite ttg suite from the singhbhum craton eastern india
    Precambrian Research, 2014
    Co-Authors: Dewashish Upadhyay, Sabyasachi Chattopadhyay, Ellen Kooijman, Klaus Mezger, Jasper Berndt
    Abstract:

    Texturally controlled dating of zircon from Paleoarchean tonaliteTrondhjemite–granodiorites of the Older Metamorphic Tonalitic Gneisses and the Singhbhum Granite batholith (Phases I, II, and III) from the Singhbhum craton in eastern India reveals a polycyclic evolution of the Archean crust. The granitoid suites were emplaced in two pulses at 3.45–3.44 Ga and 3.35–3.32 Ga. Tonalites and Trondhjemites of the Older Metamorphic Tonalitic Gneisses were emplaced at ca. 3.45–3.44 Ga together with Phase III of the Singhbhum Granite pluton while granites belonging to the Older Metamorphic Tonalitic Gneisses were emplaced at ca. 3.35–3.32 together with Phase I and Phase II of the Singhbhum Granite pluton. Both crustal units underwent an early phase of relatively high-grade metamorphism at 3.30–3.28 Ga followed by extensive fluid-induced alteration during low-grade metamorphism at 3.19–3.12 Ga, and 3.02–2.96 Ga. The two units have also been marginally affected at ca. 2.52 Ga and 1.06 Ga by major metamorphic events in the North Singhbhum Mobile Belt and the Singhbhum shear zone at the northern margin of the craton. The zircon grains in granites have inherited cores with ages of ca. 3.61 Ga and 3.46–3.41 Ga and with well-developed oscillatory growth zonation which suggests the granitic magmas were derived by partial melting of an igneous precursor or sedimentary rocks derived from an igneous source. The emplacement of the expansive granitoids belonging to the Older Metamorphic Tonalitic Gneisses and the Singhbhum Granite was synchronous with the amphibolite-facies metamorphism (ca. 3.32 Ga) of older meta-igneous and metasedimentary rocks belonging to the Older Metamorphic Group. Major felsic crust formation in the craton occurred in a narrow time interval between 3.46 and 3.32 Ma with minor contributions of material as old as 3.6 Ga. The complex polycyclic evolution of the Paleoarchean crust in the Singhbhum craton can account for the wide range of often disparate ages obtained using whole rock isochron dating techniques with some of the isochron dates being geologically meaningful while others representing mixing lines or disturbance of the isotopic systems during metamorphism.

  • Magmatic and metamorphic history of Paleoarchean tonalite–Trondhjemite–granodiorite (TTG) suite from the Singhbhum craton, eastern India
    Precambrian Research, 2014
    Co-Authors: Dewashish Upadhyay, Sabyasachi Chattopadhyay, Ellen Kooijman, Klaus Mezger, Jasper Berndt
    Abstract:

    Texturally controlled dating of zircon from Paleoarchean tonaliteTrondhjemite–granodiorites of the Older Metamorphic Tonalitic Gneisses and the Singhbhum Granite batholith (Phases I, II, and III) from the Singhbhum craton in eastern India reveals a polycyclic evolution of the Archean crust. The granitoid suites were emplaced in two pulses at 3.45–3.44 Ga and 3.35–3.32 Ga. Tonalites and Trondhjemites of the Older Metamorphic Tonalitic Gneisses were emplaced at ca. 3.45–3.44 Ga together with Phase III of the Singhbhum Granite pluton while granites belonging to the Older Metamorphic Tonalitic Gneisses were emplaced at ca. 3.35–3.32 together with Phase I and Phase II of the Singhbhum Granite pluton. Both crustal units underwent an early phase of relatively high-grade metamorphism at 3.30–3.28 Ga followed by extensive fluid-induced alteration during low-grade metamorphism at 3.19–3.12 Ga, and 3.02–2.96 Ga. The two units have also been marginally affected at ca. 2.52 Ga and 1.06 Ga by major metamorphic events in the North Singhbhum Mobile Belt and the Singhbhum shear zone at the northern margin of the craton. The zircon grains in granites have inherited cores with ages of ca. 3.61 Ga and 3.46–3.41 Ga and with well-developed oscillatory growth zonation which suggests the granitic magmas were derived by partial melting of an igneous precursor or sedimentary rocks derived from an igneous source. The emplacement of the expansive granitoids belonging to the Older Metamorphic Tonalitic Gneisses and the Singhbhum Granite was synchronous with the amphibolite-facies metamorphism (ca. 3.32 Ga) of older meta-igneous and metasedimentary rocks belonging to the Older Metamorphic Group. Major felsic crust formation in the craton occurred in a narrow time interval between 3.46 and 3.32 Ma with minor contributions of material as old as 3.6 Ga. The complex polycyclic evolution of the Paleoarchean crust in the Singhbhum craton can account for the wide range of often disparate ages obtained using whole rock isochron dating techniques with some of the isochron dates being geologically meaningful while others representing mixing lines or disturbance of the isotopic systems during metamorphism.