Spatial distribution of ultrahigh-temperature granulites of the Highland Complex of Sri Lanka: Lowermost continental crust above an ultrahot palaeo-Moho

Prasanna L. Dharmapriya; Leo Kriegsman; S.P.K. Malaviarachchi

doi:10.1016/j.lithos.2021.106484

Spatial distribution of ultrahigh-temperature granulites of the Highland Complex of Sri Lanka: Lowermost continental crust above an ultrahot palaeo-Moho

Prasanna L. Dharmapriya^*
, Leo Kriegsman
, S.P.K. Malaviarachchi

^*Corresponding author for this work

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

The spatial distribution of isolated ultra-high-temperature (UHT) granulites in Sri Lanka corresponds to the exposure level of the deepest granulites of the Highland Complex (HC). Their spatial distribution, and that of ultramafic bodies in the HC, defines a relatively thin (several km) lowermost crustal layer that has been folded into a N-plunging asymmetric fold (F₃ in our scheme), Z-shaped looking N. We postulate that the UHT granulites represent suitable lithologies within this lowermost crustal layer above an ultrahot palaeo-Moho. Prior to D₃, this layer had already been imbricated and intensely folded with the HT granulites and with ultramafic units after peak metamorphism, leading to a thick package of HT granulites with isolated UHT assemblages. This concept has some important implications for granulite terrains in general: (i) UHT granulites elsewhere may also represent a thin zone above an ultrahot palaeo-Moho and overlain by HT granulite terrains, and their spatial relationships may have been complicated by ductile deformation during early cooling; (ii) many other HT granulite terrains may be underlain by a similar zone of UHT granulites, and, if so, new discoveries of UHT terrains may be expected.

Original language	English
Article number	106484
Pages (from-to)	1-11
Journal	Lithos
Volume	404-405
DOIs	https://doi.org/10.1016/j.lithos.2021.106484
Publication status	Published - 1 Dec 2021

Bibliographical note

Funding Information:
We are grateful to the National Research Council (NRC) of Sri Lanka (Grant No. 19-092 ), the Indo-Lanka Joint Research Grant from the Ministry of Technology and Research, Sri Lanka ( MTR/TRD/AGR/3/1/04 ) to SPKM and Youth Innovation Promotion Association. PLD is also grateful for a Peradeniya University Research Grant (Grant No: URG/18/043/S ) for funding this project. LMK acknowledges support by the Stichting Dr. Schürmannfonds , Grant Nos. 88/2012 , 94/2013 and 101/2014 . Prof. T. Tsunogae and three anomalous reviewers are highly appreciated for the given detailed and constructive comments to improve the manuscript. We also thank Prof. Krishnan Sajeev for his careful and constructive editorial handling.

Publisher Copyright:
© 2021 Elsevier B.V.

Keywords

Highland Complex
Moho
Sri Lanka
Tectonics
UHT granulites

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10.1016/j.lithos.2021.106484

1-s2.0-S0024493721005272-mainFinal published version, 3.22 MBLicence: Taverne

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title = "Spatial distribution of ultrahigh-temperature granulites of the Highland Complex of Sri Lanka: Lowermost continental crust above an ultrahot palaeo-Moho",

abstract = "The spatial distribution of isolated ultra-high-temperature (UHT) granulites in Sri Lanka corresponds to the exposure level of the deepest granulites of the Highland Complex (HC). Their spatial distribution, and that of ultramafic bodies in the HC, defines a relatively thin (several km) lowermost crustal layer that has been folded into a N-plunging asymmetric fold (F3 in our scheme), Z-shaped looking N. We postulate that the UHT granulites represent suitable lithologies within this lowermost crustal layer above an ultrahot palaeo-Moho. Prior to D3, this layer had already been imbricated and intensely folded with the HT granulites and with ultramafic units after peak metamorphism, leading to a thick package of HT granulites with isolated UHT assemblages. This concept has some important implications for granulite terrains in general: (i) UHT granulites elsewhere may also represent a thin zone above an ultrahot palaeo-Moho and overlain by HT granulite terrains, and their spatial relationships may have been complicated by ductile deformation during early cooling; (ii) many other HT granulite terrains may be underlain by a similar zone of UHT granulites, and, if so, new discoveries of UHT terrains may be expected.",

keywords = "Highland Complex, Moho, Sri Lanka, Tectonics, UHT granulites",

author = "Dharmapriya, \{Prasanna L.\} and Leo Kriegsman and S.P.K. Malaviarachchi",

note = "Funding Information: We are grateful to the National Research Council (NRC) of Sri Lanka (Grant No. 19-092 ), the Indo-Lanka Joint Research Grant from the Ministry of Technology and Research, Sri Lanka ( MTR/TRD/AGR/3/1/04 ) to SPKM and Youth Innovation Promotion Association. PLD is also grateful for a Peradeniya University Research Grant (Grant No: URG/18/043/S ) for funding this project. LMK acknowledges support by the Stichting Dr. Sch{\"u}rmannfonds , Grant Nos. 88/2012 , 94/2013 and 101/2014 . Prof. T. Tsunogae and three anomalous reviewers are highly appreciated for the given detailed and constructive comments to improve the manuscript. We also thank Prof. Krishnan Sajeev for his careful and constructive editorial handling. Publisher Copyright: {\textcopyright} 2021 Elsevier B.V.",

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doi = "10.1016/j.lithos.2021.106484",

language = "English",

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AU - Dharmapriya, Prasanna L.

AU - Kriegsman, Leo

AU - Malaviarachchi, S.P.K.

N1 - Funding Information: We are grateful to the National Research Council (NRC) of Sri Lanka (Grant No. 19-092 ), the Indo-Lanka Joint Research Grant from the Ministry of Technology and Research, Sri Lanka ( MTR/TRD/AGR/3/1/04 ) to SPKM and Youth Innovation Promotion Association. PLD is also grateful for a Peradeniya University Research Grant (Grant No: URG/18/043/S ) for funding this project. LMK acknowledges support by the Stichting Dr. Schürmannfonds , Grant Nos. 88/2012 , 94/2013 and 101/2014 . Prof. T. Tsunogae and three anomalous reviewers are highly appreciated for the given detailed and constructive comments to improve the manuscript. We also thank Prof. Krishnan Sajeev for his careful and constructive editorial handling. Publisher Copyright: © 2021 Elsevier B.V.

PY - 2021/12/1

Y1 - 2021/12/1

N2 - The spatial distribution of isolated ultra-high-temperature (UHT) granulites in Sri Lanka corresponds to the exposure level of the deepest granulites of the Highland Complex (HC). Their spatial distribution, and that of ultramafic bodies in the HC, defines a relatively thin (several km) lowermost crustal layer that has been folded into a N-plunging asymmetric fold (F3 in our scheme), Z-shaped looking N. We postulate that the UHT granulites represent suitable lithologies within this lowermost crustal layer above an ultrahot palaeo-Moho. Prior to D3, this layer had already been imbricated and intensely folded with the HT granulites and with ultramafic units after peak metamorphism, leading to a thick package of HT granulites with isolated UHT assemblages. This concept has some important implications for granulite terrains in general: (i) UHT granulites elsewhere may also represent a thin zone above an ultrahot palaeo-Moho and overlain by HT granulite terrains, and their spatial relationships may have been complicated by ductile deformation during early cooling; (ii) many other HT granulite terrains may be underlain by a similar zone of UHT granulites, and, if so, new discoveries of UHT terrains may be expected.

AB - The spatial distribution of isolated ultra-high-temperature (UHT) granulites in Sri Lanka corresponds to the exposure level of the deepest granulites of the Highland Complex (HC). Their spatial distribution, and that of ultramafic bodies in the HC, defines a relatively thin (several km) lowermost crustal layer that has been folded into a N-plunging asymmetric fold (F3 in our scheme), Z-shaped looking N. We postulate that the UHT granulites represent suitable lithologies within this lowermost crustal layer above an ultrahot palaeo-Moho. Prior to D3, this layer had already been imbricated and intensely folded with the HT granulites and with ultramafic units after peak metamorphism, leading to a thick package of HT granulites with isolated UHT assemblages. This concept has some important implications for granulite terrains in general: (i) UHT granulites elsewhere may also represent a thin zone above an ultrahot palaeo-Moho and overlain by HT granulite terrains, and their spatial relationships may have been complicated by ductile deformation during early cooling; (ii) many other HT granulite terrains may be underlain by a similar zone of UHT granulites, and, if so, new discoveries of UHT terrains may be expected.

KW - Highland Complex

KW - Moho

KW - Sri Lanka

KW - Tectonics

KW - UHT granulites

U2 - 10.1016/j.lithos.2021.106484

DO - 10.1016/j.lithos.2021.106484

M3 - Article

SN - 0024-4937

VL - 404-405

SP - 1

EP - 11

JO - Lithos

JF - Lithos

M1 - 106484

ER -

Spatial distribution of ultrahigh-temperature granulites of the Highland Complex of Sri Lanka: Lowermost continental crust above an ultrahot palaeo-Moho

Abstract

Bibliographical note

Keywords

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