Meeting

Crustal evolution from the Costa Rica Rift to borehole 504B

Oceanic crust undergoes rapid transformation in both its thermal and physical structure within the first 10 Ma from the ridge axis. Large departures in observed heat flow measurements from global depth and heat flow models reveal the importance of hydrothermal systems in heat dissipation and crustal alteration. Hydrothermal systems have the greatest influence on young oceanic crust due to its high porosity and permeability and low sediment cover. Much is still unknown about the scale and processes involved, especially the interaction between the solid Earth and the oceans.

Asymmetric crustal structure of the slow-spreading Mohns Ridge

We investigate the relationship among hotspot influence, local magma supply, and asymmetric topography and crustal structure of the conjugate flanks of the slow-spreading Mohns Ridge. Residual mantle Bouguer anomaly (RMBA) was calculated by subtracting from free-air gravity the predicted attractions of water-sediment, sediment-crust, and crust-mantle interfaces as well as the effects of lithospheric cooling.

Geophysical analysis of oceanic crust at a mid-ocean ridge

The NERC-funded joint geophysical and oceanographic OSCAR project aims to develop understanding of the interactions between relatively young oceanic crust and the overlying abyssal ocean through heat transfer and fluid flow. The movement of hydrothermal fluids through the oceanic crust causes changes in its structure and composition: circulating heat, precipitating minerals in open cracks and fractures, and forming alteration fronts which influence permeability and seismic properties, though little is known about the rate and extent of these processes. 

InterRidge Bursary to Panama Basin and preliminary bathymetric interpretation

The InterRidge cruise bursary is aimed at post graduate students seeking cruise experience. This provides a vital opportunity for training in data collection and experience of scientific principles in action.  The bursary allowed me to join Dr. R. Hobbs’ JC114 cruise to the Panama basin to study the Costa Rica and Ecuador ridges. Subsequently after the cruise I became involved in the OSCAR project, ‘Oceanographic and Seismic Characterisation of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge’.

Review of Os isotope variation and model ages in ablyssal peridotite

Abyssal peridotites are of great interest to geoscientists because they provide direct information about the present-day Earth's mantle. Os isotope systems in abyssal peridotites are also interesting because Os is a highly siderophile and compatible element and so concentrates in the core in preference to the mantle, and in the mantle in preference to the crustal materials. In addition, Os in abyssal peridotites is not susceptible to metasomatism and alteration by sea water.

Systematic variations in morphological characteristics of global transform faults

We quantify systematic variations in morphological characteristics of global transform faults and investigate their dependence on spreading rate, local magma supply, and other tectonic variables. Detailed analyses were conducted on 78 transform faults where high-resolution multibeam bathymetry and other geophysical data are available.

Tamu Massif-Largest Volcano on Earth-within Shatsky Rise Oceanic Plateau Formed by Mantle Plume-Mid-Ocean Ridge Interaction?

Jinchang Zhang1,2, William W. Sager2,3, Jun Korenaga4

 

1South China Sea Institute of Oceanology, Chinese Academy of Sciences, China

2Texas A&M University, College Station, Texas, USA

3University of Houston, Houston, Texas, USA

A New Method of Automatic SVP Optimization Based on MOV Algorithm

We applied the maximum offset of sound velocity algorithm to sound velocity profile streamlining and optimization to overcome multi-beam survey and data processing efficiency problems. The impact of sound velocity profile streamlining on sounding data accuracy is evaluated. By automatically optimizing the threshold, the reduction rate of sound velocity profile data can reach over 90% and the standard deviation percentage error of sounding data can be controlled to within 0.1%.

Rare-earth-elements characteristics of the hydrothermal sulfide in the Central Indian Ridge

 A new method is proposed to identify automatically the foot of the continental slope (FOS) based on the integrated analysis of topographical profiles. First, it simplifies the topographic profiles based on second derivative extremum points and the Douglas-Peucker algorithm, and calculates a second-order derivative of the original profiles and the D-P profiles. Then, seven steps are used to simplify the original profiles and determine the slope gradient, water depth and second derivative values of data points.

Geochemical features of the hydrothermal sulfide on the Southern Mid-Atlantic Ridge near 15°S

With a systematic study on mineralogy of the three stations’ sulfide samples dredged from the seafloor hydrothermal field near 15°S Southern Mid-Atlantic Ridge, geochemical features of these sulfides are also described in detail. Bulk chemical analyses of sulfide samples were obtained using X-ray Fluorescence (XRF) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The sulfides on the Southern Mid-Atlantic Ridge (SMAR) near 15°S can be divided into three types: Fe-rich sulfide, Fe-Cu-rich sulfide and Fe-Zn-rich sulfide, and enrich Fe, Zn and Cu concentrations successively.