Paleointensity of Earth's magnetic field, with applications to the study of mid-ocean ridge accretionary processes

Reversals in the polarity of Earth's magnetic field have long been used to provide age constraints on oceanic crust and other geologic materials. More recently, it has been recognized that shorter period variations in field intensity hold the potential for placing tighter age constraints on a variety of processes and materials. Archeological artifacts, sedimentary sections, and young volcanic flows are potential candidates for paleointensity dating. This dissertation examines two kinds of records that go into providing reference curves for such dating schemes and addresses the feasibility and applications of paleomagnetic dating, focusing on mid-ocean ridge accretionary processes.; Chapter 1 is an evaluation of paleointensity data (0--5 ka) from archeological materials in the American Southwest and northwestern South America. New data is presented and placed in the context of existing data to examine regional variations in paleointensity. Such independently-dated regional curves are used in Chapter 4 to place age constraints on undated materials.; Chapter 2 examines short-period variations in sea-surface magnetic anomalies between ∼10--11 Ma. Such "tiny wiggles" allow for additional age constraints between field reversals. Though globally correlated, the nature of these tiny wiggles has not been conclusively tied to either short field reversals or simple intensity variations alone. In this chapter, a sedimentary record of relative paleointensity variations is compared to deep-tow marine magnetic anomalies in an attempt to resolve this issue.; Chapter 3 turns to paleointensity recorded in young submarine basaltic glass (SBG) at mid-ocean ridges. The chapter examines the role cooling rate may play in influencing paleointensity estimates and uses a small set of samples from the southern East Pacific Rise as a test case for dating young flows (<∼3 kyr) via paleointensity. Chapter 4 expands on this effort, presenting a large SBG data set from the northern East Pacific Rise. The chapter further examines the feasibility of dating very young flows and also attempts to provide temporal constraints on older flows (<∼50 kyr). Paleointensity variations are then interpreted in terms of temporal and spatial patterns in lava accretion at this fast-spreading ridge.