An investigation of tropical Holocene speleothems and their relationship to modern local precipitation. / Brett, Marianne.

2018. 215 p.

Research output: ThesisDoctoral Thesis

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@phdthesis{29e2dd7597c14056aaad4679f6320cdb,
title = "An investigation of tropical Holocene speleothems and their relationship to modern local precipitation",
abstract = "Holocene speleothems from NE India and the South Pacific were analysedusing a robust multi-proxy approach, with contextual environmental monitoringand daily resolution local precipitation. This study compares intraseasonaland interannual variations in precipitation amount and isotopic signature withproxy capture in speleothems to improve methods in climate reconstructionfrom speleothem proxies, and presents novel records from India and the SouthPacific.Krem Umsynrang cave, in NE India, is located in the core region of the IndianSummer Monsoon, a highly seasonal environment where the controls on interannual precipitation intensity are complex and remain to be fully understood.In the first part of this thesis, I present a new speleothem record spanningthe late Holocene, characterise seasonal proxy capture and analyse local precipitation isotopes. The study highlights the importance of fabric studies toconstruct reliable age models and interpret hydrological changes recorded inthe proxy record.Cave sites in the South Pacific afford the opportunity to reconstruct precipitationrecords of a tropical maritime environment strongly influenced by theposition of the ITCZ and the state of ENSO. I report the results of a detailedanalysis of daily precipitation isotopes from Suva, Fiji, and present a newspeleothem record from nearby island, Vatulele, as well as pilot studies fromthe island of Atiu, Cook Islands. These combine to make a novel dataset: therst proxy record to show interdecadal- and centennial-scale variability of theSouth Pacific Convergence Zone.The results argue that an interpretation of {"}the amount effect{"}, which underpinsmany palaeoclimate reconstructions from speleothem proxies, is belied bycomplex behaviour of oxygen isotopes, hence, a simple transfer function fromspeleothem calcite to rainfall amount requires corroboration from local precipitation data. The research emphasises a multi-proxy approach, supportedby cave monitoring and study of local rainfall, is crucial for palaeoclimaticreconstruction from speleothem records.",
author = "Marianne Brett",
year = "2018",
month = apr,
day = "17",
language = "English",
school = "Royal Holloway, University of London",

}

RIS

TY - THES

T1 - An investigation of tropical Holocene speleothems and their relationship to modern local precipitation

AU - Brett, Marianne

PY - 2018/4/17

Y1 - 2018/4/17

N2 - Holocene speleothems from NE India and the South Pacific were analysedusing a robust multi-proxy approach, with contextual environmental monitoringand daily resolution local precipitation. This study compares intraseasonaland interannual variations in precipitation amount and isotopic signature withproxy capture in speleothems to improve methods in climate reconstructionfrom speleothem proxies, and presents novel records from India and the SouthPacific.Krem Umsynrang cave, in NE India, is located in the core region of the IndianSummer Monsoon, a highly seasonal environment where the controls on interannual precipitation intensity are complex and remain to be fully understood.In the first part of this thesis, I present a new speleothem record spanningthe late Holocene, characterise seasonal proxy capture and analyse local precipitation isotopes. The study highlights the importance of fabric studies toconstruct reliable age models and interpret hydrological changes recorded inthe proxy record.Cave sites in the South Pacific afford the opportunity to reconstruct precipitationrecords of a tropical maritime environment strongly influenced by theposition of the ITCZ and the state of ENSO. I report the results of a detailedanalysis of daily precipitation isotopes from Suva, Fiji, and present a newspeleothem record from nearby island, Vatulele, as well as pilot studies fromthe island of Atiu, Cook Islands. These combine to make a novel dataset: therst proxy record to show interdecadal- and centennial-scale variability of theSouth Pacific Convergence Zone.The results argue that an interpretation of "the amount effect", which underpinsmany palaeoclimate reconstructions from speleothem proxies, is belied bycomplex behaviour of oxygen isotopes, hence, a simple transfer function fromspeleothem calcite to rainfall amount requires corroboration from local precipitation data. The research emphasises a multi-proxy approach, supportedby cave monitoring and study of local rainfall, is crucial for palaeoclimaticreconstruction from speleothem records.

AB - Holocene speleothems from NE India and the South Pacific were analysedusing a robust multi-proxy approach, with contextual environmental monitoringand daily resolution local precipitation. This study compares intraseasonaland interannual variations in precipitation amount and isotopic signature withproxy capture in speleothems to improve methods in climate reconstructionfrom speleothem proxies, and presents novel records from India and the SouthPacific.Krem Umsynrang cave, in NE India, is located in the core region of the IndianSummer Monsoon, a highly seasonal environment where the controls on interannual precipitation intensity are complex and remain to be fully understood.In the first part of this thesis, I present a new speleothem record spanningthe late Holocene, characterise seasonal proxy capture and analyse local precipitation isotopes. The study highlights the importance of fabric studies toconstruct reliable age models and interpret hydrological changes recorded inthe proxy record.Cave sites in the South Pacific afford the opportunity to reconstruct precipitationrecords of a tropical maritime environment strongly influenced by theposition of the ITCZ and the state of ENSO. I report the results of a detailedanalysis of daily precipitation isotopes from Suva, Fiji, and present a newspeleothem record from nearby island, Vatulele, as well as pilot studies fromthe island of Atiu, Cook Islands. These combine to make a novel dataset: therst proxy record to show interdecadal- and centennial-scale variability of theSouth Pacific Convergence Zone.The results argue that an interpretation of "the amount effect", which underpinsmany palaeoclimate reconstructions from speleothem proxies, is belied bycomplex behaviour of oxygen isotopes, hence, a simple transfer function fromspeleothem calcite to rainfall amount requires corroboration from local precipitation data. The research emphasises a multi-proxy approach, supportedby cave monitoring and study of local rainfall, is crucial for palaeoclimaticreconstruction from speleothem records.

M3 - Doctoral Thesis

ER -