Resolution Guyot

Resolution Guyot: A Seamount’s Journey Through Time

Imagine a giant mountain rising from the depths of the ocean, its summit barely peeking above the waves. This is Resolution Guyot, a fascinating geological wonder that has been shaped by millions of years of volcanic activity and environmental changes. How did this seamount come to be, and what secrets does it hold?

The Formation of Seamounts

Resolution Guyot’s story begins with a hotspot. According to the hotspot theory, volcanic activity occurs at fixed locations in the lithosphere, heated from below. As this volcanic activity continues over millions of years, it creates chains of islands and seamounts that become progressively older as you move along them. The potential hotspots involved in Resolution Guyot’s formation include Easter, Marquesas, Society, and Pitcairn.

Volcanic Phase

Eruptions built a pile of volcanic rocks, including lava flows and breccias. Over 1–2 million years, these eruptions generated a volcanic island that eventually flattened to form the platform we see today. This process is akin to stacking layers of cake, each layer representing different types of volcanic activity and rock formations.

Platform Carbonates and Reefs

About 1,619 metres (5,312 ft) of carbonate was deposited on the volcanic structure between Hauterivian and Albian periods. This sedimentation lasted for about 35 million years, creating a platform that surrounded barrier islands but featured only a few reefs. The environment on this platform included swash beaches, lagoons, and open-marine conditions, much like a tropical paradise under the sea.

Water Temperatures and Climate

The water temperatures in the early Aptian (ca. 125 – ca. 113 million years ago) were around 30–32 °C (86–90 °F). The platform was exposed to southeasterly trade winds, which left its northern side sheltered from waves except for storm-generated ones. These conditions influenced the sedimentation patterns and created a unique environment that supported diverse life forms.

Life on Resolution Guyot

The seamount hosted an array of marine life including algae, bivalves, corals, echinoderms, and more. Fossils found in the drill cores reveal the presence of rudists and sponges as bioherm builders. Microbial mats also thrived in some areas, while plant remnants suggest the existence of vegetation-covered islands on the platform.

The Rise and Fall

During the Albian to Turonian (93. 9 – 89. 8 ± 0. 3 million years ago), the carbonate platform rose above the sea by about 100 metres (330 ft)–160 metres (520 ft). This uplift episode is part of a broader tectonic change in the Pacific Ocean, with general uplift and tectonic stress changes at the ocean margins. When Resolution Guyot rose above sea level, karst processes began to impact the platform, leading to irregularities and erosion.

Drowning and Aftermath

Resolution Guyot drowned about 99 ± 2 million years ago or during the Maastrichtian period. The platform was submerged by Pliocene times, showing signs of ferromanganese and phosphate-modified rock crusts after drowning. Ferromanganese deposition began in the Turonian-Maastrichtian periods, while pelagic sediments commenced later, with Maastrichtian to Pliocene age fossils found in Hole 866B.

Resolution Guyot’s journey through time is a testament to the dynamic nature of our planet. From a volcanic island to a seamount, and finally to its current state, it has witnessed countless changes. The secrets it holds within its layers continue to intrigue scientists and offer insights into Earth’s geological history. What other wonders lie hidden beneath the waves?