عنوان

Modelling Geochemical and Geobiological Consequences of Low-Temperature Continental Serpentinization

شماره

TLpq2443888404

زبان متن نوشتاري يا گفتاري و مانند آن

انگلیسی

عنوان اصلي

Modelling Geochemical and Geobiological Consequences of Low-Temperature Continental Serpentinization

نام عام مواد

[Thesis]

نام نخستين پديدآور

Leong, James Andrew Monton

نام ساير پديدآوران

Shock, Everett

نام ناشر، پخش کننده و غيره

Arizona State University

تاریخ نشرو بخش و غیره

2020

نام خاص و کميت اثر

356

جزئيات پايان نامه و نوع درجه آن

Ph.D.

کسي که مدرک را اعطا کرده

Arizona State University

امتياز متن

2020

متن يادداشت

The hydrous alteration of ultramafic rocks, known as serpentinization, produces some of the most reduced (H2 >1 mmolal) and alkaline (pH >11) fluids on Earth. Serpentinization can proceed even at the low-temperature conditions (<50°C) characteristic of most of Earth's continental aquifers, raising questions on the limits of life deep in the subsurface and the magnitude in the flux of reduced volatiles to the surface. In this work, I explored the compositions and consequences of fluids and volatiles found in three low-temperature serpentinizing environments: (1) active hyperalkaline springs in ophiolites, (2) modern shallow and deep peridotite aquifers, and (3) komatiitic aquifers during the Archean. Around 140 fluids were sampled from the Oman ophiolite and analyzed for their compositions. Fluid compositions can be accounted for by thermodynamic simulations of reactions accompanying incipient to advanced stages of serpentinization, as well as by simulations of mass transport processes such as fluid mixing and mineral leaching. Thermodynamic calculations were also used to predict compositions of end-member fluids representative of the shallow and deep peridotite aquifers that were ultimately used to quantify energy available to various subsurface chemolithotrophs. Calculations showed that sufficient energy and power supply can be available to support deep-seated methanogens. An additional and a more diverse energy supply can be available when surfacing deep-seated fluids mix with shallow groundwater in discharge zones of the subsurface fluid pathway. Finally, the consequence of the evolving continental composition during the Archean for the global supply of H2 generated through komatiite serpentinization was quantified. Results show that the flux of serpentinization-generated H2 could have been a significant sink for O2 during most of the Archean. This O2 sink diminished greatly towards the end of the Archean as komatiites became less common and helped set the stage for the Great Oxidation Event. Overall, this study provides a framework for exploring the origins of fluid and volatile compositions, including their redox state, that can result from various low-temperature serpentinizing environments in the present and past Earth and in other rocky bodies in the solar system.

موضوع مستند نشده

Geobiology

موضوع مستند نشده

Geochemistry

موضوع مستند نشده

Mineralogy

مستند نام اشخاص تاييد نشده

Leong, James Andrew Monton

مستند نام اشخاص تاييد نشده

Shock, Everett

نام الکترونيکي

فرمت انتشار

p

نوع ماده

[Thesis]

کد کاربرگه

276903

سطح دسترسي

a

تكميل شده

Y