Delineating crustal domains in Peninsular India: Age and chemistry of orthopyroxene-bearing felsic gneisses in the Madurai Block
The Madurai Block of southern India is rich in granitic orthogneiss, much of which is orthopyroxene-bearing (charnockite). This study has identified that orthogneiss from the northwest of the Madurai Block (broadly defined as north and west of the Karur–Kambam–Painavu–Trichur lineament) has a very d...
| Main Authors: | , , , , , , |
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| Format: | Journal Article |
| Published: |
Elsevier BV
2012
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| Online Access: | http://hdl.handle.net/20.500.11937/6615 |
| _version_ | 1848745128048459776 |
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| author | Plavsa, D Collins, Alan Foden, John Kropinski, L Santosh, M Chetty, T. Clark, Chris |
| author_facet | Plavsa, D Collins, Alan Foden, John Kropinski, L Santosh, M Chetty, T. Clark, Chris |
| author_sort | Plavsa, D |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | The Madurai Block of southern India is rich in granitic orthogneiss, much of which is orthopyroxene-bearing (charnockite). This study has identified that orthogneiss from the northwest of the Madurai Block (broadly defined as north and west of the Karur–Kambam–Painavu–Trichur lineament) has a very different origin from that in the south-eastern Madurai Block. To the north and north-west of the Madurai Block, charnockites record Neoarchaean (~2.7–2.5 Ga) crystallization ages with metamorphic overprinting at ~535 Ma. Their Archaean Nd depleted mantle model ages (2.51–3.01 Ga), high ɛNd(T) values (between −3.28 and +4.55) and low to moderate initial 87Sr/86Sr ratios (0.7017–0.7106) indicate a primarily mantle-derived origin with variable involvement of Archaean crustal material. The south-east Madurai Block samples have much younger crystallization ages of 1007 ± 23 Ma and 784 ± 18 Ma and a range of Nd depleted mantle model ages between 1.38 and 1.69 Ga, suggesting a significantly different isotopic evolution of this terrane. The isotopic signature of these charnockites (ɛNd(T) = +2.58 to −3.28, initial 87Sr/86Sr = 0.7054–0.7084) suggests the involvement of a mantle source with variable input from the contemporary crust. All samples show subsequent zircon growth, or isotopic disturbance, due to Ediacaran–Cambrian metamorphism (~535 Ma).The sharply contrasting primary igneous U–Pb ages of orthogneisses identify two distinct terranes; an Archaean basement terrane to the north and west and a Proterozoic terrane dominated by metasedimentary rocks to the south and east of the Madurai Block. The isotopic boundary between the two is here defined as a broad zone south of the Karur–Kambam–Painavu–Trichur (KKPT) lineament and appears as a southerly dipping series of seismic reflectors. A correlation is made with central Madagascar where Proterozoic metsedimentary rocks are thrust over Neoarchaean orthogneisses of the Antananarivo Block. |
| first_indexed | 2025-11-14T06:12:26Z |
| format | Journal Article |
| id | curtin-20.500.11937-6615 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T06:12:26Z |
| publishDate | 2012 |
| publisher | Elsevier BV |
| recordtype | eprints |
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| spelling | curtin-20.500.11937-66152017-09-13T16:06:09Z Delineating crustal domains in Peninsular India: Age and chemistry of orthopyroxene-bearing felsic gneisses in the Madurai Block Plavsa, D Collins, Alan Foden, John Kropinski, L Santosh, M Chetty, T. Clark, Chris The Madurai Block of southern India is rich in granitic orthogneiss, much of which is orthopyroxene-bearing (charnockite). This study has identified that orthogneiss from the northwest of the Madurai Block (broadly defined as north and west of the Karur–Kambam–Painavu–Trichur lineament) has a very different origin from that in the south-eastern Madurai Block. To the north and north-west of the Madurai Block, charnockites record Neoarchaean (~2.7–2.5 Ga) crystallization ages with metamorphic overprinting at ~535 Ma. Their Archaean Nd depleted mantle model ages (2.51–3.01 Ga), high ɛNd(T) values (between −3.28 and +4.55) and low to moderate initial 87Sr/86Sr ratios (0.7017–0.7106) indicate a primarily mantle-derived origin with variable involvement of Archaean crustal material. The south-east Madurai Block samples have much younger crystallization ages of 1007 ± 23 Ma and 784 ± 18 Ma and a range of Nd depleted mantle model ages between 1.38 and 1.69 Ga, suggesting a significantly different isotopic evolution of this terrane. The isotopic signature of these charnockites (ɛNd(T) = +2.58 to −3.28, initial 87Sr/86Sr = 0.7054–0.7084) suggests the involvement of a mantle source with variable input from the contemporary crust. All samples show subsequent zircon growth, or isotopic disturbance, due to Ediacaran–Cambrian metamorphism (~535 Ma).The sharply contrasting primary igneous U–Pb ages of orthogneisses identify two distinct terranes; an Archaean basement terrane to the north and west and a Proterozoic terrane dominated by metasedimentary rocks to the south and east of the Madurai Block. The isotopic boundary between the two is here defined as a broad zone south of the Karur–Kambam–Painavu–Trichur (KKPT) lineament and appears as a southerly dipping series of seismic reflectors. A correlation is made with central Madagascar where Proterozoic metsedimentary rocks are thrust over Neoarchaean orthogneisses of the Antananarivo Block. 2012 Journal Article http://hdl.handle.net/20.500.11937/6615 10.1016/j.precamres.2011.12.013 Elsevier BV restricted |
| spellingShingle | Plavsa, D Collins, Alan Foden, John Kropinski, L Santosh, M Chetty, T. Clark, Chris Delineating crustal domains in Peninsular India: Age and chemistry of orthopyroxene-bearing felsic gneisses in the Madurai Block |
| title | Delineating crustal domains in Peninsular India: Age and chemistry of orthopyroxene-bearing felsic gneisses in the Madurai Block |
| title_full | Delineating crustal domains in Peninsular India: Age and chemistry of orthopyroxene-bearing felsic gneisses in the Madurai Block |
| title_fullStr | Delineating crustal domains in Peninsular India: Age and chemistry of orthopyroxene-bearing felsic gneisses in the Madurai Block |
| title_full_unstemmed | Delineating crustal domains in Peninsular India: Age and chemistry of orthopyroxene-bearing felsic gneisses in the Madurai Block |
| title_short | Delineating crustal domains in Peninsular India: Age and chemistry of orthopyroxene-bearing felsic gneisses in the Madurai Block |
| title_sort | delineating crustal domains in peninsular india: age and chemistry of orthopyroxene-bearing felsic gneisses in the madurai block |
| url | http://hdl.handle.net/20.500.11937/6615 |