A geo-thermochronological study offshore west of Ireland: the timing of exhumation and magmatic activity and the nature of the basement on the Irish Atlantic Margin
APPROVED In recent years, the use of multiple low-temperature thermochronometers combined with inverse thermal history modelling of multiple samples on vertical profiles has been shown capable of detecting low magnitude exhumation events that characterise many passive margins. Such approaches have s...
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| Other Authors: | , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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Trinity College Dublin. School of Natural Sciences. Discipline of Geology
2021
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| Online Access: | http://hdl.handle.net/2262/97303 https://tcdlocalportal.tcd.ie/pls/EnterApex/f?p=800:71:0::::P71_USERNAME:RATEAUR |
| Summary: | APPROVED In recent years, the use of multiple low-temperature thermochronometers combined with inverse thermal history modelling of multiple samples on vertical profiles has been shown capable of detecting low magnitude exhumation events that characterise many passive margins. Such approaches have shed new insights on the Mesozoic and Cenozoic exhumation history of onshore Ireland and Britain. A similar approach has been used in this study to investigate the exhumation history of the Irish Atlantic Margin (IAM), the southern segment of the North-East Atlantic Margin, which until now has been primarily studied by apatite fission track dating in isolation. More than 40 new samples (from PAD and Ifremer) were acquired from borehole cuttings and cores and seabed dredge samples all along the IAM (from the Donegal and NE Rockall basins to the north to the southern tip of the Porcupine High and the Goban Spur to the south). After compiling all the low-temperature thermochronological data from Ireland and the UK, a set of legacy AFT and AHe samples was also selected to complement the new samples, as half of the samples collected in this study did not yield enough apatite. Zircon and apatite U/Pb dating and apatite trace element determinations were undertaken to constrain the thermal history model and derive new insights on the timing of magmatism and nature of the basement offshore west of Ireland. The thermal histories derived from the thermochronological data show that the investigated segments of the IAM are dominated by Late Jurassic and Early Cretaceous cooling associated with the main phases of rifting and hyperextension in the Porcupine and Rockall basins and between the Celtic margin and its conjugate margins (North Iberia and Canada). North to south diachronous Mesozoic cooling and exhumation has been observed in thermal histories employing vertical profiles on earlier studies on the western Ireland onshore. This study shows that such a trend is not observed on the IAM. Instead, the AFT age spatial pattern ... |
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