The Cenozoic evolution of the South Vietnam margin of the South China Sea and the origin of coastal placer deposits

Vietnam mineral reserves contribute significantly to its economy and South Vietnam is especially rich in these resources. Whilst this region is well known as a source of oil and gas, extracted from offshore basins it is also an exporter of titanium ore extracted from coastal sands rich in heavy minerals. Despite decades of exploitation there remain fundamental questions about the origins of these resources that form the aims of this thesis. Specifically, 1) Where did the titanium bearing mineral known as ilmenite found in the heavy mineral sands come from? 2) How is the sedimentation history of the hydrocarbon basins connected to the uplift and erosion history of South Vietnam? To answer these questions an extensive set of rock and sand samples were collected from across the region and analysed using a combination of detrital zircon geochronology, petrology, geochemistry and apatite thermochronometry. In answer to question one results showed that the placer sands along coastal southern Vietnam came from local river catchments rich in outcrops of Cretaceous granites. The geochemical and petrological data also showed ilmenite titanium contents increased to the south, explained by a wider continental shelf that increased exposure to weathering during glacial sea-level lowstands before rising sea- levels remobilised the sand. Question two was answered by apatite thermochronometry data that detected increased rock uplift between 25-15 Ma across most of South Vietnam. This timing is significant as local marine basins also show inversion and a regional unconformity at the Oligocene/Miocene boundary. Following inversion basins subsided under the load of thick sands produced by erosion of the onshore region. These data provide the first solid link between basin sedimentation and onshore erosion. The cause of uplift is likely related to a change in regional stress field linked to ocean spreading in the South China Sea

The Cenozoic evolution of the South Vietnam margin of the South China Sea and the origin of coastal placer deposits

Vietnam mineral reserves contribute significantly to its economy and South Vietnam is especially rich in these resources. Whilst this region is well known as a source of oil and gas, extracted from offshore basins it is also an exporter of titanium ore extracted from coastal sands rich in heavy minerals. Despite decades of exploitation there remain fundamental questions about the origins of these resources that form the aims of this thesis. Specifically, 1) Where did the titanium bearing mineral known as ilmenite found in the heavy mineral sands come from? 2) How is the sedimentation history of the hydrocarbon basins connected to the uplift and erosion history of South Vietnam? To answer these questions an extensive set of rock and sand samples were collected from across the region and analysed using a combination of detrital zircon geochronology, petrology, geochemistry and apatite thermochronometry. In answer to question one results showed that the placer sands along coastal southern Vietnam came from local river catchments rich in outcrops of Cretaceous granites. The geochemical and petrological data also showed ilmenite titanium contents increased to the south, explained by a wider continental shelf that increased exposure to weathering during glacial sea-level lowstands before rising sea- levels remobilised the sand. Question two was answered by apatite thermochronometry data that detected increased rock uplift between 25-15 Ma across most of South Vietnam. This timing is significant as local marine basins also show inversion and a regional unconformity at the Oligocene/Miocene boundary. Following inversion basins subsided under the load of thick sands produced by erosion of the onshore region. These data provide the first solid link between basin sedimentation and onshore erosion. The cause of uplift is likely related to a change in regional stress field linked to ocean spreading in the South China Sea

Differentially Private Publication of Social Graphs at Linear Cost

International audienceThe problem of private publication of graph data has attracted a lot of attention recently. The prevalence of differential privacy makes the problem more promising. However, a large body of existing works on differentially private release of graphs have not answered the question about the upper bounds of privacy budgets. In this paper, for the first time, such a bound is provided. We prove that with a privacy budget of O(log n), there exists an algorithm capable of releasing a noisy output graph with edge edit distance of O(1) against the true graph. At the same time, the complexity of our algorithm Top-m Filter is linear in the number of edges m. This lifts the limits of the state-of-the-art, which incur a complexity of O(n^2) where n is the number of nodes and runnable only on graphs having n of tens of thousands

Enforcing Privacy in Decentralized Mobile Social Networks

International audienceThis position paper first summarizes work done by the first author on location privacy and differential privacy. These techniques will help to solve privacy problems in decentralized mobile social networks, which is the main theme of his PhD research. The paper then briefly reviews the state-of-the-art in privacy-preservation of social graphs and clarifies the lack of attention to graph sharing in decentralized setting. Finally, some initial ideas on how to realize such soft decentralized access controls are described

A Maximum Variance Approach for Graph Anonymization

Best Paper AwardInternational audienceUncertain graphs, a form of uncertain data, have recently attracted a lot of attention as they can represent inherent uncertainty in collected data. The uncertain graphs pose challenges to conventional data processing techniques and open new research directions. Going in the reserve direction, this paper focuses on the problem of anonymizing a deterministic graph by converting it into an uncertain form. The paper first analyzes drawbacks in a recent uncertainty-based anonymization scheme and then proposes Maximum Variance, a novel approach that provides better tradeoff between privacy and utility. Towards a fair com-parison between the anonymization schemes on graphs, the second con-tribution of this paper is to describe a quantifying framework for graph anonymization by assessing privacy and utility scores of typical schemes in a unified space. The extensive experiments show the effectiveness and efficiency of Maximum Variance on three large real graphs

Enforcing Privacy in Decentralized Mobile Social Networks

International audienceThis position paper first summarizes work done by the first author on location privacy and differential privacy. These techniques will help to solve privacy problems in decentralized mobile social networks, which is the main theme of his PhD research. The paper then briefly reviews the state-of-the-art in privacy-preservation of social graphs and clarifies the lack of attention to graph sharing in decentralized setting. Finally, some initial ideas on how to realize such soft decentralized access controls are described

Towards Safer Operations: An Expert-involved Dataset of High-Pressure Gas Incidents for Preventing Future Failures

This paper introduces a new IncidentAI dataset for safety prevention. Different from prior corpora that usually contain a single task, our dataset comprises three tasks: named entity recognition, cause-effect extraction, and information retrieval. The dataset is annotated by domain experts who have at least six years of practical experience as high-pressure gas conservation managers. We validate the contribution of the dataset in the scenario of safety prevention. Preliminary results on the three tasks show that NLP techniques are beneficial for analyzing incident reports to prevent future failures. The dataset facilitates future research in NLP and incident management communities. The access to the dataset is also provided (the IncidentAI dataset is available at: https://github.com/Cinnamon/incident-ai-dataset).Comment: Accepted by EMNLP 2023 (The Industry Track

Evolution of the Continental Margin of South to Central Vietnam and Its Relationship to Opening of the South China Sea (East Vietnam Sea)

The continental margin of south to central Vietnam is notable for its high elevation plateaus many of which are covered by late Cenozoic basalt flows. It forms the westernmost margin of a wide continental rift of the South China Sea (East Vietnam Sea), and uplift has been considered a result of either rifting or younger intraplate basalt magmatism. To investigate margin development apatite thermochronometry was applied to a dense array of samples collected from across and along the margin of south to central Vietnam. Results, including thermal history models, identified a distinct regional episode of fast cooling between c. 37 and 30 Ma after which cooling rates remained low. The fast cooling coincides with a period of fast extension across the South China Sea (East Sea) region that preceded continental break-up recorded by Oligocene grabens onshore. A thermal model is used test different processes that might influence the inferred cooling including a distinct pulse of exhumation; a decrease in exhumation followed by an associated transient decrease in geothermal gradients and, underplating coincident with rifting. Thermal relaxation following Mesozoic arc magmatism is ruled out as geotherms returned to background rates within 20 Myrs of emplacement, well before the onset of fast cooling. Models support fast cooling attributed to accelerated erosion during early stages of rifting. Some additional heating from either underplating, and/or hot mantle upwellings is also possible. No evidence was found to support regional uplift associated with the intraplate magmatism, enhanced monsoon-driven erosion or seafloor spreading dynamics

Research Notes : Exotic soybean observational yield performance trial in Kien Gian province --Mekong Delta --Vietnam --dry season 1981-1982

In the light of mutual technical assistance, six soybean varieties, namely \u27Bon minori\u27 (2 lines), \u27Enrei\u27 (2 lines), \u27Akiyoshi\u27 and \u27Hyuuga\u27, were forwarded by registered mail from Japan to Vietnam in May, 1981. Due to its long postal course, soybean seed was only received in November 1981. A month later, seeds were planted on December 10, 1981, at the provincial seed farm of Kien Giang province and then harvested on February 26, 1982

A Bayesian belief data mining approach applied to rice and shrimp aquaculture

In many parts of the world, conditions for small scale agriculture are worsening, creating challenges in achieving consistent yields. The use of automated decision support tools, such as Bayesian Belief Networks (BBNs), can assist producers to respond to these factors. This paper describes a decision support system developed to assist farmers on the Mekong Delta, Vietnam, who grow both rice and shrimp crops in the same pond, based on an existing BBN. The BBN was previously developed in collaboration with local farmers and extension officers to represent their collective perceptions and understanding of their farming system and the risks to production that they face. This BBN can be used to provide insight into the probable consequences of farming decisions, given prevailing environmental conditions, however, it does not provide direct guidance on the optimal decision given those decisions. In this paper, the BBN is analysed using a novel, temporally-inspired data mining approach to systematically determine the agricultural decisions that farmers perceive as optimal at distinct periods in the growing and harvesting cycle, given the prevailing agricultural conditions. Using a novel form of data mining that combines with visual analytics, the results of this analysis allow the farmer to input the environmental conditions in a given growing period. They then receive recommendations that represent the collective view of the expert knowledge encoded in the BBN allowing them to maximise the probability of successful crops. Encoding the results of the data mining/inspection approach into the mobile Decision Support System helps farmers access explicit recommendations from the collective local farming community as to the optimal farming decisions, given the prevailing environmental conditions