Two-thirds of submarine volcanism in the Earth's ocean basins is manifested along mid-ocean ridges and the remaining one-third is revealed along intraoceanic arcs and seamounts. Hydrothermal systems and the circulation patterns associated with these volcanic settings remove heat from the solid Earth into the deep ocean. Hydrothermal circulation continues to remove and redistribute heat in the crust as it ages. The heat and mass fluxes added to the deep ocean influence mixing in the abyssal ocean thereby affecting global thermohaline circulation. In addition to removing heat, hydrothermal processes extract chemical components from the oceanic and carry it to the surface of the ocean floor, while also removing certain elements from seawater. The resulting geochemical cycling has ramifications on the localized mineral deposits and also the biota that utilize these chemical fluxes as nutrients. In this dissertation, I analyze observed conductive heat flow measurements in the Panama Basin and borehole thermal measurements in Brothers Volcano and use mathematical models to estimate advective heat and mass fluxes, and crustal permeability. In the first manuscript, I use a well-mixed aquifer model to explain the heat transport in a sediment pond in the inactive part of the Ecuador Fracture Zone. This model yields mass fluxes and permeabilities similar to estimates at young upper oceanic crust suggesting vigorous convection beneath the sediment layer. In the second manuscript, I analyze the conductive heat flow measurements made in oceanic between 1.5 and 5.7 Ma on the southern flank of the Costa Rica Rift. These data show a mean conductive heat deficit of 70%, and this deficit is explained by various hydrothermal advective transport mechanisms, including outcrop to outcrop circulation, transport through faults, and redistribution of heat by flow of hydrothermal fluids in the basement. In the third manuscript, I analyze the borehole temperature logs for two sites representative of recharge and discharge areas of hydrothermal systems in the Brothers Volcano. I develop upflow and downflow models for fluids in the borehole and formation resulting in estimated of flow rates and permeabilities. All three independent research works are connected by the common thread of utilizing relatively simple mathematical concepts to get new insights into hydrothermal processes in oceanic crust. / PHD / Two-thirds of underwater volcanic activity in the Earth’s ocean basins is exhibited in areas where new material for Earth’s outer shell is created and the remaining one-third is displayed along areas where the outer shell is destroyed. In these areas, hot springs that are under water and their water movement patterns remove heat from the solid outer shell and puts it into the deepest parts of the ocean. Hot water circulation continues to remove and redistribute heat and various chemical elements in the shell as it grows old. This heat and chemical elements, which get added to the deep ocean water, influences the way water mixes and forms layers in the world oceans. This also affects the movement of ocean currents. The chemical elements removed from the shell by hot water gets deposited as minerals on the ocean floor in places where hot springs arise. This variety of minerals provides nutrients for different marine organisms. In this work done during my PhD studies, I examine the heat and temperature that was measured in the Panama Basin and Brothers Volcano. I utilize these examinations to build simple math models to find out how much heat and chemical components are being added to the deep ocean water. I also find out the methods in which the hot water springs appear on the ocean floor and the patterns in which the hot water circulates in the Earth’s outer shell. All of these estimates will help the scientists who are studying the patterns and changes in ocean currents by giving them a number on how much heat is released from the inside of the Earth.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/99631 |
| Date | 15 February 2019 |
| Creators | Kolandaivelu, Kannikha Parameswari |
| Contributors | Geosciences, Lowell, Robert P., King, Scott D., Hole, John A., Pollyea, Ryan M. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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