TY - CONF TI - A origem e evolução dos magmas graníticos de Macao à luz de dados de geoquímica elementar e isotópica / Source and evolution of Macao granitic magmas: insights from wholerock geochemistry and isotopic signatures. AU - Dias, Ágata AU - Quelhas, P AU - Mata, J AU - Lou, U T AU - Ribeiro, M L AU - Borges, R T2 - XIV Congresso de Geoquímica dos Países de Língua Portuguesa e XIX Semana de Geoquímica (XIV CGPLP/XIX SG, international conference C1 - Trás-os-Montes e Alto Douro, Portugal DA - 2018/// PY - 2018 ER - TY - CONF TI - Diving into the unknown: robotics as tools to study the deep-sea. Informed Scientific Sampling in Large-scale Outdoor Environments AU - Dias, Ágata T2 - International Conference on Intelligent Robots and Systems IROS C1 - Macau DA - 2019/// PY - 2019 ER - TY - JOUR TI - Geochemistry and stable isotope constraints on high-temperature activity from sediment cores of the Saldanha hydrothermal field AU - Dias, Ágata AU - Früh-Green, G.L. AU - Bernasconi, S.M. AU - Barriga, F.J.A.S. T2 - Marine Geology DA - 2011/01// PY - 2011 DO - 10.1016/j.margeo.2010.10.017 VL - 279 IS - 1-4 SP - 128 EP - 140 J2 - Marine Geology LA - en SN - 00253227 UR - https://linkinghub.elsevier.com/retrieve/pii/S0025322710002884 Y2 - 2021/03/30/07:34:19 ER - TY - CONF TI - Geochemistry of Fe-Si-(Mn) Chimneys from Luso Vent Field, MAR AU - Dias, Ágata AU - Costa, P AU - Marques, A F AU - Ribeiro, L AU - Madureira, P AU - Calado, A AU - Gonçalves, E AU - Morato, T T2 - Goldschmidt C1 - Barcelona DA - 2019/// PY - 2019 UR - https://goldschmidt.info/2019/abstracts/abstractView?id=2019003072 ER - TY - CONF TI - Geochronological, geochemical and petrographic constraints on incremental pluton growth: the case of Macao granitic suite AU - Dias, Ágata AU - Quelhas, P AU - Mata, J AU - Wayne, Davis T2 - Goldschmidt C1 - Barcelona DA - 2019/// PY - 2019 UR - https://goldschmidt.info/2019/abstracts/abstractView?id=2019004459 ER - TY - CONF TI - Hydrothermal Fe-Mn deposits from low-temperature systems of the Mid-Atlantic Ridge AU - Costa, P AU - Dias, Ágata T2 - InterRidge Workshop on Hydrothermal Ore-forming Processes C1 - Hangzhou DA - 2019/// PY - 2019 ER - TY - RPRT TI - MaGIC – Petrology and Geochemistry of Igneous Rocks from Macao: Implications for the Crustal Evolution of Southern China. AU - Dias, Ágata CY - Macao DA - 2017/// PY - 2017 M3 - Research Report PB - University of Saint Joseph ER - TY - JOUR TI - Mesozoic Granitic Magmatism in Macao, Southeast China AU - Quelhas, P. M. AU - Mata, J. AU - Lou, U. T. AU - Ribeiro, M. L. AU - Dias, Ágata T2 - AGU Fall Meeting Abstracts AB - Macao ( 30 Km2) is a territory characterized by small granitic intrusions, located along the coastal region of Southeast China (Cathaysia Block). Granitoids occur as different facies, including microgranite dykes, with distinct textural, mineralogical and geochemical features, for which a middle-upper Jurassic age ( 164 Ma) has been proposed. New data suggest that these granitoids are mostly high-K calc-alkaline metaluminous (A/CNK = 0.8 - 1.1) biotite granites, consistent with total absence of primary muscovite. They show variable amounts of SiO2 (67-77%), reflecting different degrees of magmatic evolution. There is also variability in terms of trace elements, particularly Rare Earth Elements (REEs), evidenced by decreasing (La/Sm)N, (Gd/Lu)N, (Ce/Yb)N and (Eu/Eu*)N towards the more evolved samples, which can be partly attributed to fractional crystallization processes. Most of the granitoids are characterized by (La/Yb)N = 3 - 10.8, showing negative Ba, Nb, Sr, Zr, P, Ti and Eu anomalies. On the other hand, microgranite dykes, along with a few more evolved granites, show an opposite tendency, being usually enriched in HREEs relatively to LREEs with (La/Yb)N = 0.4 - 1.1. Our data suggests intermediate genetic affinities between I-type and A-type granites. Although these granitoids are mostly metaluminous (characteristic of I-types), Ga/Al ratios, usually used to identify A-types, are close to the accepted boundary between A-type and other granite types. The affinities with A-type granites are more marked for the more evolved facies, which depict higher values of FeOt/MgO (14 - 60) and K2O/MgO (60 - 250). Their trace element characteristics are also transitional between WPG (Within-plate granites) and Syn-COLG (Collision Granites). We interpret those transitional characteristics (A/I and WPG/Syn-COLG) of Macao granitoids as reflecting an origin by melting of infracrustal sources over a period of high heat transfer from mantle to crust during an extensional tectonic setting probably contemporaneous with the subduction of the paleo-Pacific plate beneath the Eurasia, whose paleo-suture is thought to be located in the east flank of the Central Range, Taiwan. DA - 2016/12/01/ PY - 2016 VL - 11 J2 - AGU Fall Meeting Abstracts UR - http://adsabs.harvard.edu/abs/2016AGUFM.V11B2775Q Y2 - 2021/03/30/08:21:09 KW - 8499 General or miscellaneous KW - VOLCANOLOGY ER - TY - CONF TI - New geochemical constraints on I-type granites of Macao: evidences for fractional crystallization and petrogenetic affinities with Jurassic-Cretaceous granites in SE China AU - Dias, Ágata AU - Quelhas, P AU - Mata, J AU - Lou, U T AU - Borges, R AU - Ribeiro, M. L T2 - Goldschmidt DA - 2017/// PY - 2017 UR - https://goldschmidtabstracts.info/2017/3248.pdf ER - TY - CONF TI - Petrology and Geochemistry of Granitic Rocks from Macao AU - Dias, Ágata AU - Quelhas, P AU - Lou, U AU - Mata, J AU - Ribeiro, M L T2 - Goldschmidt C1 - Yokohama, Japan DA - 2016/// PY - 2016 UR - https://goldschmidtabstracts.info/2016/665.pdf ER - TY - RPRT TI - Petrology and Geochemistry of Igneous Rocks from Macao: Implications for the Crustal Evolution of Southern China AU - Dias, Ágata CY - Macao DA - 2016/// PY - 2016 M3 - Research Report PB - University of Saint Joseph ER - TY - RPRT TI - Petrology and Geochemistry of Igneous Rocks from Macao: Implications for the Crustal Evolution of Southern China AU - Dias, Ágata CY - Macao DA - 2018/// PY - 2018 M3 - Research Report PB - University of Saint Joseph ER - TY - THES TI - Petrology and geochemistry of the igneous rocks from Macao (South China) :tectono-magmatic implications AU - Quelhas, Pedro Moniz A3 - Dias, Ágata A3 - Mata, João AB - The territory of Macao is composed of several granitic intrusions belonging to one of the biggest granite provinces in the world, the Southeast China Magmatic Belt (SCMB), located in the southeast (SE) area of the Cathaysia Block. The SCMB is known by the occurrence of large volumes of Mesozoic magmatic rocks (over 90% are granitic rocks and equivalent volcanic rocks with minor basalts), occupying a total outcrop area of nearly 200.000 km2. The geology of Macao (~30 Km2) is dominated by granitic rocks displaying a wide range of textural, mineralogical and chemical features, making it an ideal region to study these rocks and the petrogenetic processes responsible for their diversity. This study employed a wide range of research methodologies, namely field studies, petrography, zircon geochronology, mineral chemistry, whole-rock elemental and isotopic geochemistry to determine the nature of the source, the petrogenetic processes and the tectonic regimes of the Mesozoic magmatism in this region. Thus, the data collected along this study aims to provide new knowledge on the tectono-magmatic evolution of Macao, in particular, and of SE China, in general. The results obtained from the high-precision U–Pb zircon geochronology, acquired through isotope dilution thermal ionization mass spectrometry (ID-TIMS) and in-situ laser ablation multi-collector inductively coupled mass spectrometry (LA-MC-ICPMS), revealed different ages for Macao granites. Despite its relatively small area, the determined ages tightly constrain the Macao granitic magmatism to two periods, ranging from 164.5 ± 0.6 to 162.9 ± 0.7 Ma (MGI – Macao Group I granites) and 156.6 ± 0.2 to 155.5 ± 0.8 Ma (MGII – Macao Group II granites). In addition, younger dacitic rocks were dated at 150.6 ± 0.6 Ma and <120 Ma. The existence of two proximal but distinct granitic pulses, spanning for a time of about 9 Ma and separated by ca. 6 Ma, in the Macao granitic suite suggests that it was incrementally assembled. This hypothesis is also extendable to the neighbouring Hong Kong region, where the magmatic activity occurred in four major pulses spanning for about 24 Ma. However, the MGII granites indicate the occurrence, on the Pearl River Delta region, of a magmatic pulse between those defined in Hong Kong at the origin of Lamma Suite (165–160 Ma) and the Kwai Chung Suite (148–146 Ma). In addition, Rare Element Earth (REE) ratios suggest that this pulse may only occur in Macao area, while MGI granites show evolving trends of REE ratios similar to those of Jurassic granites outcropping in vast areas of the Cathaysia Block (SE China). Inheritance patterns in the zircon U–Pb data indicate the presence of a population of antecrysts (165–180 Ma) crystallized from earlier magmatic pulses and a population of inherited zircons, from Precambrian to Phanerozoic sources, incorporated into the magmas during melting and/or ascent/emplacement at crustal levels. The oldest inherited ages (2.4 Ga and possibly 2.9 Ga) suggest contribution of Proterozoic and possibly of late Archaean crustal sources for the Macao magmatism. The granitic rocks of Macao are mainly high-K calc-alkaline metaluminous to weakly peraluminous I-type granites with variable degrees of fractionation. Fractional crystallization played an important role in the evolution of these granites, though the fractionation paths differ for the highly fractionated facies of both groups mainly due to distinct accessory fractionating phases. Such difference is evident by distinct REE evolution trends: while MGI magmas seem to have evolved by gradual enrichment in heavy REE relatively to light REE, originating progressively flatter REE patterns, magmas from MGII are marked by depletion of middle REE, leading to progressively concave upward REE patterns. However, while most of the geochemical variation of the MGII granites can be explained by fractional crystallization, the same is not true for MGI granites. The MGI highly fractionated granites show evidence for the REE tetrad effect and are characterized by non-CHArge-and-RAdius-Controlled (non-CHARAC) behaviour of trace elements, suggesting late-stage melt/fluid interactions involving F-rich fluids. The stage of evolution represented by the MGI highly fractionated granites corresponds to the onset of fluid/melt interaction in a highly evolved granitic system, which may have led to enhanced hydrothermal activity in more evolved stages, as those represented in neighbouring areas in SE China. Significant differences in isotopic composition were also observed, with the MGII being characterized by a much narrow range of initial 87Sr/86Sr ratios and εNd(t) and εHf(t) values than MGI. Based on these differences, the MGII granites are considered to be part of a comagmatic suite that has evolved in closed system, contrasting with what can be inferred for MGI. The increase in initial 87Sr/86Sr ratios with degree of evolution, the presence of metasedimentary enclaves and the high percentage of inherited zircon with Paleozoic ages in MGI, suggest the occurrence of an assimilation fractionation crystallization (AFC) process. The AFC processes were a major cause for the I-S transitional characteristics of the MGI highly fractionated granites and possibly of the other similar Jurassic biotite granites in SE China. The observed decoupling of Sr, Nd and Hf isotope systems might have resulted from magma mixing between the granitic and more mafic magmas, which caused the homogenization of Sr isotope ratios but not of the Nd and Hf ones. Such process is also supported by the occurrence of Microgranular Mafic Enclaves (MME) hosted by the granites. Isotope and major element compositions together with model ages strongly suggest that Macao granitic magmas were generated by partial melting of infracrustal medium-to-high K basaltic Paleo-Proterozoic to Mesoproterozoic protoliths heated by, and mixed to some degree with mantle-derived magmas. The temporal and spatial association of Macao and SE China Jurassic I-type granites with basaltic/gabbroic rocks, syenites and A-type granites, displaying typical intraplate chemical features, indicates an extensional regime rather than an active margin for the origin of these rocks. It also points to an important role of mantle-derived magmas in the production of SE China Jurassic granites. Adiabatic decompression melting of the asthenospheric mantle produced mafic magmas, which underplated at the base of the crust (Moho), subsequently triggering partial melting of the lower crust to generate the granitic magmas. The Jurassic Macao granites are interpreted as being produced in an intraplate extensional setting related to the break-off and foundering of a previously flat-slab (Paleo-Pacific plate) beneath the Eurasian plate. The boundary between east and west Cathaysia blocks is roughly along the Zhenghe-Dapu Fault (ZDF), which intersects the SE China coast near Hong Kong and is thought to have played a major role for the Mesozoic magmatic activity in this region. The stronger isotopic affinities of Macao granites with the other granitic rocks and lower crustal xenoliths from the western Cathaysia Block suggest that the ZDF is likely to pass south of Macao, a fact that has not been mentioned before. In addition to the Early Yanshanian (Jurassic) granitic magmatism in Macao, the younger ages obtained for the dacite dykes indicate that the territory was also affected, to a lesser degree, by Late Yanshanian (Cretaceous) magmatism. The transition from granitic to dacitic magmatism most likely corresponds to a change in the regional tectonic regime, which induced a significant change in the magma genesis processes. In contrast with the intraplate features of Macao and SE China Jurassic granites and coeval mafic rocks, the geochemical features of the Macao dacite dykes (e.g. high LILE/HFSE ratios and negative anomalies of Nb, Ta and Ti) are identical to those characterizing arc-like subduction-related magmas. These dacites are most likely evolved products of arc-like magmatism and may testify the reestablishment of a normal subduction system in this area of SE China. CN - D-SC 2019 QUE,PED CY - Macao DA - 2019/// PY - 2019 DP - USJ Library SP - 400 LA - English M3 - PhD in Science PB - University of Saint Joseph; Universidade de Lisboa. Faculdade de Ciências ST - Petrology and geochemistry of the igneous rocks from Macao (South China) UR - http://library-opac.usj.edu.mo/cgi-bin/koha/opac-detail.pl?biblionumber=173252 KW - Thesis and Dissertations PhD in Science (D-SC) KW - University of Saint Joseph ER - TY - RPRT TI - Research Projects: Petrology and Geochemistry of Igneous Rocks from Macao: Implications for the Crustal Evolution of Southern China AU - Dias, Ágata CY - Macao DA - 2018/// PY - 2018 M3 - Research Report PB - University of Saint Joseph ER - TY - CONF TI - Saldanha hydrothermal field: the role of the sediment-cover in the preservation of ore-forming minerals AU - Dias, Ágata AU - Barriga, F T2 - Third InterRidge Theoretical Institute: Magmatic and Tectonic Processes and Seabed Resources at Mid-Ocean Ridges. T2-09 C1 - Hangzhou, China DA - 2015/// PY - 2015 ER - TY - CONF TI - Sr and Nd isotopic composition of Jan Mayen and Loki’s Castle: a progress report AU - Cruz, M I AU - Marques, F A M AU - Dias, Ágata AU - Pedersen, R AU - Barriga, F T2 - 43rd Underwater Mining Institute DA - 2014/// PY - 2014 ER - TY - CONF TI - Sulfide mineralization of the Saldanha hydrothermal field (MAR): constraints from sulfur isotope in-situ microanalysis AU - Dias, Ágata AU - Qiu, W AU - Barriga, F AU - Tao, C T2 - InterRidge Workshop on Hydrothermal Ore-forming Processes C1 - Hangzhou DA - 2019/// PY - 2019 ER - TY - CONF TI - Sulfide Sites in the Arctic Ocean: Jan Mayen and Loki’s Castle, Mineralogical Magazine AU - Cruz, M I AU - Marques, A F AU - Dias, Ágata AU - Pedersen, R AU - Relvas, J M R S AU - Barriga, F J A S T2 - Goldschmidt DA - 2013/// PY - 2013 UR - https://goldschmidtabstracts.info/abstracts/abstractView?id=2013003606 ER - TY - CONF TI - Sulphide mineralization in Arctic seafloor hydrothermal fields: extending the European exploration area to the Far North AU - Cruz, M I AU - Dias, Ágata AU - Pedersen, R B AU - Relvas, J M R S AU - Fonseca, R AU - Barriga, F J A S T2 - ERA-MIN. DA - 2013/// PY - 2013 ER - TY - JOUR TI - Surface sediment composition and distribution of hydrothermal derived elements at the Duanqiao-1 hydrothermal field, Southwest Indian Ridge AU - Dias, Ágata AU - Liao, Shili AU - Tao, Chunhui AU - Su, Xin AU - Yang, Zhen AU - Ni, Jianyu AU - Liang, Jin AU - Yang, Weifang AU - Liu, Jia AU - Li, Wei AU - Dong, Chuanwan T2 - Marine Geology DA - 2019/10// PY - 2019 DO - 10.1016/j.margeo.2019.105975 VL - 416 SP - 105975 J2 - Marine Geology LA - en SN - 00253227 UR - https://linkinghub.elsevier.com/retrieve/pii/S0025322719300969 Y2 - 2021/03/30/07:30:43 ER -