Discovery of the marine Eocene in the northern South China Sea

National Science Review, Journal Year: 2019, Volume and Issue: 6(5), P. 881 - 885

Published: June 25, 2019

Language: Английский

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Strontium isotope stratigraphy and LA-ICP-MS U-Pb carbonate age constraints on the Cenozoic tectonic evolution of the southern South China Sea

Geological Society of America Bulletin, Journal Year: 2022, Volume and Issue: 135(1-2), P. 271 - 285

Published: May 6, 2022

Abstract The tectonic evolution of the South China Sea is closely associated with multiple subduction-collision processes in Southeast Asia. When collision Dangerous Grounds terrane Sabah-Palawan Islands terminated debated due to poor age constraints at southern margin Sea. A deep well drilled on Meiji Atoll penetrates Cenozoic carbonate strata central Grounds. Robust strontium isotope ages and laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) U-Pb dates provide critical chronological middle Miocene hiatus spanning 9 m.y. thought be mainly caused by uplift was accompanied underthrusting beneath Palawan orogenic uplifting north Borneo during Miocene. Data interpretation indicates an active regrowth above represents end this event ca. 11 Ma, after cessation seafloor spreading, which occurred 15 Ma.

Language: Английский

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Phylogenomics of Fresh and Formalin Specimens Resolves the Systematics of Old World Mud Snakes (Serpentes: Homalopsidae) and Expands Biogeographic Inference

Bulletin of the Society of Systematic Biologists, Journal Year: 2023, Volume and Issue: 2(1), P. 1 - 24

Published: Sept. 13, 2023

Our knowledge of the biodiversity Asia and Australasia continues to expand with more focused studies on systematics various groups their biogeography. Historically, fluctuating sea levels cyclic connection separation now-disjunct landmasses have been invoked explain accumulation via species pump mechanisms. However, recent research has shown that geological shifts mainland dispersal events may be better explanations in these regions. We investigate processes using poorly studied geographically widespread Mud Snakes (Serpentes: Homalopsidae) a target capture approach ~4,800 nuclear loci from fresh tissues supplemental mitochondrial data formalin museum specimens. use datasets reconstruct first resolved phylogeny group, identify biogeographic origins, test hypotheses regarding roles sea-level change habitat selection diversification. Divergence dating ancestral range estimation yielded support for an Oligocene origin diversification Southeast Sundaland rear-fanged group ~20 million years ago, followed by eastward westward dispersal. GeoHiSSE models indicate niche expansion ancestral, lineages into aquatic environments did not impact rates. results highlight Pleistocene changes specificity primarily lead extant richness Homalopsidae that, alternatively, major driver diversity this group. also emphasize importance degraded tissues, both DNA, filling gaps known but highly diverse conceptually important groups. Here, represents non-traditional effective model study system understanding transitions between terrestrial, marine, freshwater environments.

Language: Английский

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Spatial distribution, geochemistry and provenance of heavy minerals in Miri beach sediments, NW Borneo, Malaysia

Environmental Earth Sciences, Journal Year: 2025, Volume and Issue: 84(6)

Published: March 1, 2025

Abstract In this study, the spatial distribution of heavy minerals (HMs) in Miri beach sediments was assessed to quantify abundance and determine provenance. Surface sediment samples were collected beaches during low tide with respect longitudinal, lateral depth samplings. The processed for grain size analysis by using sieving method. Then HMs separation at different fractions carried out gravity magnetic methods. Polarising Microscope used identify various present samples. addition, selected analysed X-ray Fluorescence (XRF) elemental composition major oxides geochemistry From results, found zircon, magnetite, tourmaline, rutile. Magnetite abundant 600–250 μm fraction, zircon 125–63 tourmaline rutile 250–125 fraction. Longitudinally, magnetite have higher towards southern part coastline. However, northern Zircon more middle parts Laterally, concentration landward side. terms depth, varies surface sample. Geochemically, be highly weathered north (CIA = 78.9), moderately 63.8 66.5) poorly 40.4–49.6). high content quartz are derived from quartzose sedimentary origin, which undergone recycling process. Environmental indices such as contamination factor (CF), geoaccumulation index (Igeo), enrichment (EF) indicate that concentrated Cr, Ni, Ta.

Language: Английский

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Uncertainty-Driven Modeling of Microporosity and Permeability in Clastic Reservoirs Using Random Forest

Published: April 3, 2025

Predicting microporosity and permeability in clastic reservoirs is a challenge reservoir quality assessment, especially formations where direct measurements are difficult or expensive. These properties fundamental determining reservoir's capacity for fluid storage transmission, yet conventional methods evaluating them, such as Mercury Injection Capillary Pressure (MICP) Scanning Electron Microscopy (SEM), resource-intensive. The aim of this study to develop cost-effective machine learning model predict complex using readily available field data basic laboratory analyses. A Random Forest classifier was employed, utilizing key geological parameters porosity, grain size distribution, spectral gamma-ray (SGR) measurements. An uncertainty analysis applied account natural variability, expanding the dataset, enhancing model's robustness. achieved high level accuracy predicting (93%) levels (88%). By easily obtainable data, reduces reliance on expensive methods, making it valuable tool early-stage exploration, remote offshore environments. integration with provides reliable approach siliciclastic formations. This offers practical solution improve assessments, enabling more informed decision-making optimizing exploration efforts.

Language: Английский

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Adakites without a slab: Remelting of hydrous basalt in the crust and shallow mantle of Borneo to produce the Miocene Sintang Suite and Bau Suite magmatism of West Sarawak

Lithos, Journal Year: 2019, Volume and Issue: 344-345, P. 100 - 121

Published: June 15, 2019

Language: Английский

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Oligocene-Miocene drainage evolution of NW Borneo: Stratigraphy, sedimentology and provenance of Tatau-Nyalau province sediments

Journal of Asian Earth Sciences, Journal Year: 2020, Volume and Issue: 195, P. 104331 - 104331

Published: March 19, 2020

Language: Английский

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Strontium isotope stratigraphy of late Cenozoic fossiliferous marine deposits in North Borneo (Brunei, and Sarawak, Malaysia)

Journal of Asian Earth Sciences, Journal Year: 2022, Volume and Issue: 231, P. 105213 - 105213

Published: April 12, 2022

Neogene marine deposits of North Borneo are locally very rich in fossils that provide glimpses into the past biodiversity. However, dating these onshore sediments with biostratigraphy is often hampered by lack and/or poor preservation state index fossils. Therefore, fossiliferous sites were targeted strontium isotope stratigraphy (SIS) to obtain higher precision relative dating. Well-preserved macrofossils screened using a multidisciplinary approach, and 87Sr/86Sr ratios most pristine remains used date embedding sediments. Most measured ages fall expected chronostratigraphic framework established large scale studies for region. The oldest, Burdigalian (early Miocene) Sibuti Formation Sarawak (17.71 ± 0.2My 16.7 0.2My) followed Serravallian (middle age within Belait Fm Brunei (12.1 + 1.4/-1.2My). Eight localities from younger units, Miri Seria formations Brunei, gave range 10.5 1 7.0 0.9/-0.5My (Tortonian-Messinian). Reworked fossil assemblages Tutong beach also investigated SIS Late Miocene support an origin part Fm. One locality, Lumapas where limestone crops out unexpected (Tortonian, late Miocene, 10.6 1My) compared estimates projected its assumed stratigraphic position lower (late Burdigalian). These challenging data require more research, yet if young accepted, situation needs further revision.

Language: Английский

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Geochemistry of Cenozoic coals from Sarawak Basin, Malaysia: implications for paleoclimate, depositional conditions, and controls on petroleum potential

International Journal of Coal Science & Technology, Journal Year: 2024, Volume and Issue: 11(1)

Published: June 4, 2024

Abstract Forty Tertiary coals from Mukah-Balingian and Merit-Pila coalfields of the Sarawak Basin, Malaysia were investigated using bulk molecular geochemical techniques such as proximate analysis, gas chromatography-mass spectrometry, elemental analyser, isotope ratio mass inductively coupled plasma spectrometry to reconstruct their paleovegetation, paleoclimate, environments deposition. In addition, principal component analysis (PCA) selected parameters was carried out determine controlling influences on petroleum potential humic coals. δ 13 C values abundance terpenoids imply predominant contribution angiosperms paleoflora. Bimetal proxies (Sr/Ba, Sr/Cu, C-value), δD are generally suggestive a warm humid climate during accumulation paleopeats. However, n -alkane ( P wax , aq -C 23 / 29 etc.) polycyclic aromatic hydrocarbons (PAHs) distribution suggest that Balingian accumulated under relatively drier strongly seasonal paleoclimate in Late Pliocene. When compared with published global average abundances, mostly depleted major oxides trace elements, suggesting peat freshwater-influenced environments. Nonetheless, higher (> 0.5 wt%) total sulfur content some suggests degree epigenetic marine influence. Furthermore, low moderately-high ash contents Basin indicate presence ombrotrophic rheotrophic deposits. PCA result source input, paleoflora, incursions not potential. climatic, depositional conditions appear slightly influence studied

Language: Английский

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Provenance of Oligocene–Miocene sedimentary rocks in the Cuu Long and Nam Con Son basins, Vietnam and early history of the Mekong River

International Journal of Earth Sciences, Journal Year: 2022, Volume and Issue: 111(6), P. 1773 - 1804

Published: July 4, 2022

Abstract The offshore Cuu Long (CLB) and Nam Con Son (NCSB) basins of SE Vietnam are two important Cenozoic hydrocarbon-bearing in the southern South China Sea (SCS), which can contribute to understanding evolution major Asian river systems, particular Mekong River. Oligocene Early Miocene basin fill Basin is dominated by sediment sourced locally from Da Lat Zone basement on land. Sandstones have abundant Cretaceous detrital zircons heavy mineral assemblages apatite epidote. Bach Ho Unconformity at c. 16 20.5 Ma marks a provenance change overlying Middle Late Dong Nai formations were large system, drained Indochina or even Himalaya, resembling present-day These heterogeneous zircon populations Triassic ages zircon–rutile–tourmaline-dominated assemblages. Cau Dua similar CLB formations, indicating comparable drainage history proto-Chao Phraya. At 15.4 17 signature changes predominant Sibumasu signature. early River suggested involved systems. A proto-Mekong 1 initially filled CLB, while same time Phraya with capture area into Himalaya Malay and/or NCSB. end was completely reorganised, captured headwaters became 2, NCSB Malay–Thai Peninsula. This very reorganisation SCS region.

Language: Английский

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