Tag: Earth Sciences
Public lecture: Hydrothermal fields from the Mid-Atlantic Ridge – The role of brecciate rocks in ore formation
By Isabel Costa (INCITE and IDL-FCUL)
Lucky Strike and Menez Gwen hydrothermal fields are located in the Mid-Atlantic Ridge (MAR), southwest of the Azores islands. In the areas surrounding the active sites, the alteration processes affecting basaltic rocks are prominent and form hydrothermal breccias by the circulation of low temperature hydrothermal fluids in diffuse vents. These breccias play an important role in the protection of subseafloor hydrothermal sulphide deposits by forming an impermeable cap due to the high content in siliceous material. Since the discovery and description of recent mineralized submarine hydrothermal deposits, comparison with ancient volcanic massive sulphide deposits is appropriate. Thus, the model for the formation of the Atlantic brecciated rocks can explain some of the processes taking place in the early phase of development of old deposits, where equivalent siliceous material is found in the hanging wall of the ore bodies.
Public lecture: SEAFLOOR MINERAL RESOURCES by Prof. Vesselin Dekov
on 4th Dec., 2018, 6:00pm
@ ISE, USJ – Institute of Science and Environment of the University of Saint Joseph. Speakers´ Hall. Rua de Londres 106, Macau, China. 中國澳門倫敦街一零六號（環宇豪庭三樓）
The lecture will discuss the main characteristics, types, mode of formation, occurrence and economic value of the major seafloor mineral resources. It will comment on the mineral potential of the continental margins and formation of marine placers, on the formation and possible mining of the polymetallic Mn-nodules at the abyssal plains, on the deposition of Co-rich Fe-Mn-crusts at the seamounts, and on the spectacular polymetallic hydrothermal sulphides precipitated at mid-ocean ridges, back-arc basins and volcanic arcs. The lecture is designed for students, researchers but also for non-professionals.
On 13th of November Prof. Ágata Alveirinho Dias visited the department of Earth Sciences of the University of Hong Kong.
She met Prof Mei-Fu Zhou, Prof. Zhao, Prof. Min Sun and Prof. Jin and worked in the ICP-MS lab running Hf isotopic analyses on zircons from granites of Macau
EArth and Marine Sciences
Our studies combine tools in mineralogy and petrology, geochemistry (including radiogenic and stable isotope geochemistry) and cartography to research the following two topics:
DEEP-SEA HYDROTHERMAL SYSTEMS AND MINERAL DEPOSITS
The discovery of hydrothermal fields on the seafloor was one of the greatest scientific discoveries of the last century not only for the earth sciences but also for the life sciences. These systems are oasis of life in the otherwise inconspicuous seafloor where vents emanate hot fluids rich in metals that are used as an energy source by unique and spectacular vent-associated organisms. For this reason, the study of hydrothermal systems may provide clues on diverse topics such as how live can thrive in extreme and toxic conditions or how potential ore resource are formed. Our research on seafloor hydrothermal systems aims to understand the genesis, evolution and distribution of hydrothermal deposits in the deep-sea. It is mainly focused in the Mid-Atlantic Ridge (MAR) and in the Southwest Indian Ridge (SWIR). The main goals of this research are: to understand the contribution of mafic and ultramafic rocks on the deposition of hydrothermal ore deposits; to contribute with the development of tools for the detection of SMS deposits either active and discrete, diffuse and inactive; to contribute for the geochemical and mineralogical characterization of deep-seafloor deposits both on active and discrete hydrothermal; to understand the role of sub-seafloor ore-forming hydrothermal systems on the preservation of sulphide minerals.
GEOLOGY OF MACAO
Macao is located on the Southeast (SE) China coast, south of Guangdong Province, about 50 km west of Hong Kong. In this area, there is a predominance of granitic intrusions that belong to the ~ 3500 km long and ~ 800 km wide NE-trending magmatic belt cropping out on the SE part of the Cathaysia Block.
Our research includes the study of the origin and evolution of the magmas of Macao, as well as the dating of its magmatic events. It has further allowed developing a detailed digital cartographic map of the igneous rocks of Macao, and to contribute to a deeper understanding of the South China tectono-magmatic evolution.