Graduation Year

2019

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Geology

Major Professor

Bogdan P. Onac, Ph.D.

Committee Member

Joan J. Fornós, Ph.D.

Committee Member

Victor J. Polyak, Ph.D.

Committee Member

Ping Wang, Ph.D.

Keywords

Flowstones, Karst Geomorphology, Paleokarst, Stalagmites, U-series

Abstract

Sea level affects the littoral morphology and structure in different ways. In coastal karst basins, dissolutional and depositional processes are strictly related to sea level variation. A great variety of karst-related geomorphological features and cave deposits exist above, below, and at sea level, and are extremely useful to study past changes of relative sea level. Within these, vadose speleothems such as flowstones and stalagmite, can document unequivocal maximum sea level constraints as well as record phreatic phases of sea level rise. Here we present a series of geochronological data from the eastern Mallorca and show the implication of relative sea level oscillations in the coastal karst evolution over the last 750 kyr. We investigate a total number of twenty-two samples between flowstones and stalagmites from different paleokarst sites and coastal caves. U-series ages of samples ranged between 650 and 450 kyr for the paleo-flowstones, and 225-198 ka and 85.7-83.7 ka for the stalagmites. The paleo-speleothems records provide new timing constraints regarding periods of vadose conditions suggesting that sea level did not exceed 2 mapsl during the interglacial highstands 17, 15, and 13. Periodic sea level oscillations following glacial/interglacial cycles caused morphostructural changes of the paleo-caves. We constrain the occurrence of breakdown events to intervals succeeding the sea level highstands 11, 9, 7, and 5, and further total breakdowns and dismantling of caves throughout the Holocene. We also present two stalagmite records of relative sea level maximum at ~1 mbpsl during the MIS 7, and constraints for sea level rise and paleoenvironmental changes during the MIS 5a. We conclude pointing out the necessity to use vadose speleothems along with other RSL records to precisely estimate past sea level changes.

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