University of Alabama, The
A tour of the Mariana Subduction System part of MARGINS Data in the Classroom:MARGINS Mini-Lessons
This is an interactive lecture based around a geophysical (primarily bathmetry and seismic reflection data) tour of the Mariana convergent margin. Through a powerpoint presentation and optional GeoMapApp and GeoWall visualizations Students explore the principal provinces of the Mariana convergent margin from the subducting plate through the backarc. The Mariana convergent margin is a classic trench-volcanic arc-back arc system in the western Pacific. The deepest point on the Earth's surface, the Challenger Deep, is found at its southern end, just to the south of the U.S. territory of Guam. To the north the Mariana convergent margin transitions into the Izu-Bonin arc, which eventually intersects Japan. Subduction initially began at about 50 Ma. A volcanic island arc had formed by the Late Middle Eocene (~44 Ma) and then rifted in the Late Eocene to Early Oligocene. Subsequent spreading, from 29 Ma to 15 Ma, propagated north and south creating the Parece Vela back-arc basin. At ~9 Ma the arc again rifted, and seafloor spreading in the Mariana Trough back-arc basin, beginning at ~5 Ma, rafted away the remnant arc. Rifting and spreading propagated north, increasing the curvature of the Mariana island arc system. Explosive volcanism is ongoing along the modern Mariana arc. From 16â20.5ÂN most of the active arc volcanoes are subaerial; south of 16ÂN they are all submarine. The modern Mariana Trough is characterized by prominent abyssal hill fabric. Oceanic crust and abyssal hill fabric in the east are buried under thick volcaniclastic sediments derived from the active arc. The extent of accreted back-arc basin crust on the eastern margin of the basin, proximal to the active volcanic arc, and the locations of paleospreading axes are unknown. In general, the spreading center is 40â50 km closer to the Mariana Arc than the remnant arc, suggesting asymmetrical crustal accretion or alternatively, that the active arc is constructed primarily on accreted lithosphere. Any asymmetry of the Mariana Trough may be caused by repetitive, small-scale ridge jumps to the east, towards the subduction zone. In this model, seafloor accretion along individual spreading segments would primarily be symmetric, but the ridge jumps would result in an overall asymmetric basin. Arc rifting and back-arc basin formation are commonly thought to be caused by extension induced by the seaward migration of the trench, termed "trench rollback". However, in the central Mariana system where the near vertical subducting plate acts as a "sea anchor" resisting lateral motion, this may not be the case. Back-arc basin spreading along this region of the Mariana system may be caused by the combined effects of the sea anchor force and convergence of the Philippine Sea and Eurasian Plates. In contrast, the increase in spreading rate of the southern Mariana Trough may be the result of trench rollback along the Challenger Deep segment of the Mariana Trench
The Woodlark Basin as a Natural Laboratory for the Study of the Geological Sciences part of MARGINS Data in the Classroom:MARGINS Mini-Lessons
The Woodlark Basin is located to the northeast of Australia and between Papua New Guinea and the Solomon Islands. Within this small region active examples of most tectonic processes can be found. Using the freely available program ArcReader, students will explore an ArcGIS database with the goal of examining some of the geological features of this exciting area. This activity is designed as a culminating exercise in a semester long series of introductory geology labs. Students will have the opportunity to apply much of the knowledge that they have acquired over the course of the semester to a single geological region. Among other things they will explore the volcanic activity, seismicity, rock types, plate boundaries, topography, and mineral resources of this rich area.
Oil and Gas Exploration Project part of Cutting Edge:Introductory Courses:Activities
Students play the role of a geologist for an oil and gas exploration company. Given a budget and some basic geological information they are required to bid on leases, explore, drill, and hopefully produce at a profit.
Water flow in the subsurface part of Cutting Edge:Introductory Courses:Activities
Using an off-the-shelf mock-up of a hydrological system, students are asked to predict where water will flow. Dyed water is injected into various parts of the system so that the students can see the flow patterns.
The Woodlark Basin as a Natural Laboratory for the Study of the Geological Sciences part of Cutting Edge:Geophysics:Workshop 07:Geophysics Activities
This activity is designed to show introductory physical geology students how geoscientists use many different types of data to solve a geological problem. In this exercise the students integrate basic geological and geophysical data to study the geology of the Papua New Guinea region, including the Woodlark Basin. This is done in the context of a GIS database.
Sustainable Earth part of Cutting Edge:Introductory Courses:Courses
This four-hour natural science course provides an understanding of important Earth resources and how their utilization impacts the environment through water pollution, air pollution and hazardous waste production. Laboratory includes an introduction to geographic information systems (GIS) and field trips to local sites of environmental interest.
Early Career Workshop 2012: Leader