Hydrothermal Circulation and Seawater Chemistry

Exploring how oceanic hydrothermal systems influence seawater chemistry

The chemical exchange between seawater and the underlying ocean crust occurs at temperatures ranging from about 2°C on the seafloor to more than 500°C deep in the crust. These hydrothermal reactions strongly influence the chemical composition of seawater and, in turn, seawater chemistry impacts hydrothermal exchange; these feedbacks play a crucial role in the Earth system.

Hydrothermal Circulation and Seawater Chemistry: Links and Feedbacks explores on- and off-axis hydrothermal systems and their effects on ocean chemistry and the Earth system.

Volume highlights include:

• Hydrothermal fluxes dependent on boundary conditions such as climate and sedimentation history
• Low-temperature, off-axis systems that have large fluxes of elements
• Observational and experimental perspectives of on-axis hydrothermal processes
• Methods for tracking hydrothermal and oceanic processes using sediments or isotope proxies
• The role of oceanic hydrothermal systems in planetary-scale cycles on Earth and beyond

The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.

List of Contributors vii

Preface xi

1 A Brief Introduction to Potential Links and Feedbacks Between Hydrothermal Processes and Seawater

Chemistry 1

Laurence A. Coogan, Alexandra V. Turchyn, Ann G. Dunlea, and Wolfgang Bach

2 Geochemical Controls on the Composition of Hydrothermal Vent Fluids at Mid-Ocean Ridges 19

William E. Seyfried Jr., Guy N. Evans, and Yanlu Xing

3 Experimental Geochemistry Techniques Applied to the Interpretation of High-Temperature Inorganic

Geochemistry of Mid-Ocean Ridge Hydrothermal Systems 45

Drew D. Syverson and Guy N. Evans

4 The Influence of Seawater Mixing on the Element Budgets in Basalt-Hosted Mid-Ocean Ridge

Hydrothermal Systems 71

Alexander Diehl and Wolfgang Bach

5 A Review of Macrobiology–Microbiology Interactions at Mid-Ocean Ridge Hydrothermal Systems

and Their Role in Mediating Element Fluxes into the Ocean 91

Laurel R. Yohe and Drew D. Syverson

6 Instruments and Observations Needed for Better Understanding of Hydrothermal Fluxes Across

the Seafloor 111

Lianfu Li, Shichuan Xi, and Xin Zhang

7 The Marine Sediment Archive of Hydrothermal Activity 137

Ann G. Dunlea, Jennifer L. Middleton, and Frank J. Pavia

8 The Effect of Seawater Sr Concentration on the Hydrothermal Alteration of Oceanic Crust:

Sr Isotopes in Dikes of the Early Paleozoic Bay of Islands Ophiolite 169

Daniel A. Stolper, Daniel E. Ibarra, Amanda L. Bednarick, Claire E. Bucholz, Laurence A. Coogan,

Kathryn M. Gillis, Max Lloyd, John N. Christensen, and Donald J. DePaolo

9 Low-Temperature Ridge Flank Heat and Fluid Fluxes, Contributions to Global Biogeochemical

Cycles, and Archives of Changing Global Conditions 187

Rosalind M. Coggon, Aled D. Evans, Lewis J.C. Grant, and Damon A.H. Teagle

10 The Effect of Off-Axis Hydrothermal Systems on the Oceanic Mg Budget as Revealed by Mg Isotopes:

A Review 225

Netta Shalev and Danielle Santiago Ramos

11 Seafloor Weathering: Lessons from Studies of the Critical Zone 253

Louis A. Derry

12 A Historical Perspective on Long-Term Global Biogeochemical Box Models 263

Preston Cosslett Kemeny, Alex Krause, and Lee Kump

13 Extreme Supercontinental Climate Control: Punctuated Mantle Thermal Mixing and a Sustained

Snowball Earth? 297

A. Mark Jellinek and Adrian Lenardic

14 Geochemical and Geophysical Controls on Hydrothermal Fluxes on Habitable Worlds 325

Benjamin M. Tutolo and Nicholas J. Tosca

15 The Role of Hydrothermal Processes in the Evolution of Early Earth and Aquaplanets 347

Takazo Shibuya, Shuya Tan, Sakiko Kikuchi, Hisahiro Ueda, Ken Takai, and Yasuhito Sekine

Index 383