Marine Geosciences

The study area is located in western Pacific Ocean, Mariana Trench. The aim of the data analysis is to analyse the potential influence of how various geological and tectonic factors may affect the geomorphological shape of the Mariana Trench. Statistical analysis of the data set in marine geology and oceanography requires an adequate strategy on big data processing. In this context, current re- search proposes a combination of the Python-based methodology that couples GIS geospatial data analysis. The Quantum GIS part of the methodology produces an optimized representative sampling dataset consisting of 25 cross-section profiles having in total 12,590 bathymetric observation points. The sampling of the geospatial dataset are located across the Mariana Trench. The second part of the methodology consists of statistical data processing by means of high-level programming language Python. Current research uses libraries Pandas, NumPy and SciPy. The data processing also involves the subsampling of two auxiliary masked data frames from the initial large data set that only consists of the target variables: sediment thickness, slope angle degrees and bathymetric observation points across four tectonic plates: Pacific, Philippine, Mariana, and Caroline. Finally, the data were analysed by several approaches: 1) Kernel Density Estimation (KDE) for analysis of the probability of data distribution; 2) stacked area chart for visualization of the data range across various segments of the trench; 3) spacial series of radar charts; 4) stacked bar plots showing the data distribution by tectonic plates; 5) stacked bar charts for correlation of sediment thickness by profiles, versus distance from the igneous volcanic areas; 6) circular pie plots visualizing data distribution by 25 profiles; 7) scatterplot matrices for correlation analysis between marine geologic variables. The results presented a distinct correlation between the geologic, tectonic and oceanographic variables. Six Python codes are provided in full for repeatability of this research.

Seismic stratigraphy and structural analysis of seismic data, when combined with wireline data, provides vital information for hydrocarbon exploration in a prospective basin. These techniques were employed in the Songo Songo shallow coastal basin, southern Tanzania to determine stratigraphic setting, trapping mechanism, reservoirs zones. Suites of well logs from two wells (AA-1 and BB-5) and 2-D seismic data was obtained from TPDC in the study area. Lithologic interpretation and well correlation were carried out using the well log suites. Stratigraphic analysis was carried out with the well logs and 2D seismic data by using principles of sequence stratigraphy while structural interpretation was done with aid of the seismic data to produce polar plots for the different structural trends. The lithology was dominated by sand, shale, and limestone. Five sequence boundaries (SB); SB1 (Albian), SB2 (base of Coniacian-Early Campanian), SB3, (Middle Eocene), SB4 (Late Miocene) and SB5 (Quaternary)) and three maximum flooding surfaces (MFS); MFS1-(Early Cretaceous), MFS2, (Late Cretaceous), MFS3-(Early Eocene) were identified. Three main normal faulting systems (Jurassic faults, active during the Jurassic rifting phase of Madagascar, Neogene faults that occurred during Neogene east African rifting and reactivated faults which mostly were Jurassic fault reactivated by east African rifting) of NNW-SSE were recognized in the study area. The structural interpretation reveal that the gas field is dominated by normal faults that occur in the upper and lower part of Songo Songo suggesting two phases of deformation prior to development of the field. The main reservoir is developed in the Neocomian and Albian sandstones, and capped by Jurassic faults and Wami (Formation) overlying rocks. The gas is sourced from Jurassic shale known as Mtumbei Formation and stored at the main reservoir developed in the Lower Cretaceous aged Neocomian sandstone known as Kipatimu Formation, sealed by high pressured shale of upper Cretaceous known as Wami Formation. This study shows that deposition of sediment occurs in the NW – SE direction, with the thinning of sediments thickness towards well BB-5 while the stratigraphic sections show that the horizons are laterally continuous and are being strongly affected by tectonic events.

ABSTRAK
Pesisir Karawang merupakan salah satu daerah potensi tangkapan ikan kakap di Indonesia. Tumpahan minyak yang terjadi di Perairan Utara Karawang pada tanggal 12 Juli 2019 berpotensi mempengaruhi karakteristik klorofil-a dan suhu permukaan laut (SPL) sebagai parameter penentuan daerah tangkapan ikan kakap. Tujuan penelitian ini adalah: (a) mengetahui hubungan tumpahan minyak terhadap karakteristik klorofil-a dan SPL dan (b) mengetahui distribusi potensi daerah tangkapan ikan kakap pasca tumpahan minyak. Metode penelitian yang digunakan adalah ekstraksi klorofil-a dan SPL menggunakan citra MODIS level 3 dengan algoritma O’Reilly dan komparasi beberapa transformasi indeks pada citra Landsat 8 OLI, yaitu Oil Spill Index dan NDVI. Hasil pengolahan data klorofil-a, zona potensi tangkapan ikan  yang berdekatan dengan sumber kebocoran minyak mengalami penurunan nilai klorofil-a dengan interval nilai 1-2 mg/m3. Pengolahan suhu menunjukkan adanya indikasi peningkatan suhu yang cukup signifikan di daerah Kepulauan Seribu 1 (satu)  minggu pasca kebocoran minyak, namun secara umum di daerah lain, hubungan tumpahan minyak terhadap perubahan suhu tidak terlalu signifikan. Hasil pengolahan Oil Spill Index dan NDVI pada citra Landsat 8 OLI secara visual mampu menunjukkan secara jelas lokasi tumpahan minyak. Perbandingan histogram Landsat 8 OLI sebelum ( perekaman 9 Juli 2019) dan sesudah kejadian (perekaman 25 Juli 2019), menunjukkan adanya tren peningkatan frekuensi nilai piksel yang tinggi pada perekaman 25 Juli 2019 yang menunjukkan adanya indikasi tumpahan minyak.
Kata kunci : tumpahan minyak,  klorofil-a dan SPL, daerah potensi tangkapan ikan

The paper discusses the imperatives of sand mining and the environmental
impacts using selected case histories in the Niger Delta and elsewhere. The
continuation of sand mining in spite of the associated adverse environmental
effects, have been linked to the creation of new usable land from marginal
lands of the region and sustained supply of aggregates for expansion of civil
infrastructure. The case studies highlight the project cycle of sand mining
and the circumstances in which environmental peculiarities influence
the procedures and strategies for abstraction. The major concerns of sand
mining in the riverbeds and open sea are accelerated coastal and riverbank
erosion, surface water turbidity due to re-suspended sediment load, threats to
coastal infrastructure and the prospect of wider dispersion of contaminated
sediments with extended effects on water quality, health and safety of marine
life. The paper emphasizes the need to integrate mitigative measures of
potential impacts into the planning and execution of sand mining projects.

Sensitive High-Resolution Ion Microprobe (SHRIMP) U–Th–Pb isotopic data of detrital zircons from mature, quartz-rich meta-sandstones are used to constrain possible tectonic affinities and source regions of the rhythmically layered and graded-bedded series in the Yeoncheon Complex (Imjingang Belt) and the correlative Taean Formation. These metamorphic marine turbidite sequences presently occur along the Paleoproterozoic (1.93–1.83 Ga) Gyeonggi Massif, central Korea's main high-grade metamorphic gneiss terrane. Yet, detrital zircons yielded highly similar multimodal age spectra with peaks that do not match the age repartition in these basement rocks, as late (1.9–1.8 Ga) and earliest (∼ 2.5 Ga) Paleoproterozoic detrital modes are subordinate but, in contrast, Paleozoic (440–425 Ma) and Neoproterozoic (980–920 Ma) spikes are prominent, yet the basement essentially lacks lithologies with such ages. The youngest concordant zircon ages in each sample are: 378, 394 and 423 Ma. The maturity of the meta-sandstones and the general roundness of zircons of magmatic signature, irrespective of their age, suggest that sediments underwent considerable transport from source to sink, and possibly important weathering and recycling, which may have filtered out irradiation-weakened metamorphic zircon grains. In combination with these isotopic data, presence of a low-angle ductile fault contact between the Yeoncheon Complex and the Taean Formation and the underlying mylonitized Precambrian basement implies that they are in tectonic contact and do not have a stratigraphic relationship, as often assumed. Consequently, in all likelihood, both meta-sedimentary formations: (1) are at least of early Late Devonian age, (2) received much of their detritus from distant (reworked) Silurian–Devonian and Early Neoproterozoic magmatic sources, not present in the Gyeonggi Massif, (3) and not from Paleoproterozoic crystalline rocks of this massif, or other Korean Precambrian basement terranes, and (4) should be viewed as independent tectonic units that had sources not exposed in Korea. A thorough literature review reveals that the Yeoncheon Complex and the Taean Formation were potentially sourced from the Liuling, Nanwan and Foziling groups in the Qinling–Dabie Belt, which all show very similar detrital zircon age spectra. These immature middle–late Devonian sandstones were deposited in a pro-foreland basin formed as a result of the aborted subduction of the South Qinling Terrane below the North Qinling Terrane, which was uplifted and eroded during post-collision isostatic rebound. The submarine fans where the mature distal turbiditic Yeoncheon and Taean sandstones were deposited may have constituted the eastern terminal part of a routing system originating in the uplifted and eroded middle Paleozoic Qinling Belt and adjacent part of the foreland basin.

Understanding of ecology in the past, present and future temperatures can be possible to do by analysis abundance of fossil foraminifera. This research was conducted in Sambipitu Formation, Ngalang River, Nglipar, Gunung Kidul Regency. The research method is spatial, observation and sampling every 5 meters, Descriptive, analyzing samples consisting of a 10gram sample, biostratigraphy analysis and paleoecology analysis using abundance of fossil, diversity analysis, and comparing current temperature data. Biostratigraphy used as a parameter in assisting the determination of paleoecology, which can be evidence of changes of ecology at a certain age seen datum and biozones. Based on paleontological analysis found appearance and abundance of foraminifera bentonic which characterize the salinity environment in the Sambipitu Formation with early-to-late miocene. as well as the results obtained by fauna association (foraminifera), that the study area showed salinity normal marine water. From the analysis we found 1 phase of pelotemperatur based on appearance of Globorotalia menardii, Globigerinoides trilobus, Globigerinoides ruber, Orbulina universa, and appearance of Pulleniatina obliqueculata showing paleotemperature phase Warm Water Area and Warm Water Area (average surface water approximate 25oC).

Keywords: Abundance, Biostratigraphy, Paleoecology, Sambipitu Formation.

FLÓRIO, Ricardo Amorim. Identificação dos principais indicadores físicoambientais e parâmetros meteorológicos para avaliação de suscetibilidade à erosão da zona costeira de Saquarema e Marica (RJ). Rio de Janeiro. UFRJ/MN/DGP. 2007. Monografia (Curso de Especialização em Geologia do
Quaternário).
O compartimento litorâneo de aproximadamente 19 Km, compreendido
entre os municípios de Saquarema e Maricá (RJ), balizados pelos pontões cristalinos de Nossa Senhora de Nazaré (Saquarema) e de Ponta Negra (Maricá) têm experimentado nos últimos anos, ataques de ondas de grande energia, que provocaram danos de grande monta às estruturas humanas estabelecidas ao longo da zona litorânea, cuja gênese está relacionada ao ingresso de frentes-frias. Todavia, tem-se verificado impactos diferenciais ao longo do compartimento litorâneo (FLÓRIO, 2003), evidenciando-se trechos com maiores danos e prejuízos que outros, como exemplo, a ressaca ocorrida em maio de 2001. Com amparo em estudos realizados por Bush et al. (1999) e Morton (2002),
a presente pesquisa possibilitou a identificação dos principais indicadores físicos que influenciam na suscetibilidade da linha de costa à erosão, bem como destacou a importância dos fatores meteorológicos e sua variáveis de influência nos processos costeiros e morfologia praial. A contextualização dos dados pesquisados no âmbito da presente pesquisa, tem por objetivo fornecer mais uma alternativa para pesquisadores e/ou órgãos interessados nas ações referentes à predição e mitigação dos danos decorrentes de eventos de ressacas, sinalizando, preferencialmente, para o monitoramento constante dos indicadores e dados de variáveis meteorológicas locais, armazenamento e sistematização dos dados, produção de modelos e mapas de suscetibilidade visando planos de ação pontual e diferencial ao longo do
compartimento litorâneo.

The Korean peninsula is located in the eastern margin of the Eurasian continent where major late Palaeozoic to early Mesozoic continental collision zones, like the Central Asian Orogenic Belt and the Central China Orogen, merge with circum-Pacific subduction-accretion systems. We present an integrated view of the Korean collision belt using recent Ar/Ar laser-probe step-heating single grain ages from the uppermost Gyeonggi Massif, central Korea's Palaeoproterozoic high-grade granite-gneiss terrane affected by Permo-Triassic metamorphism, the bordering Hongseong zone and the overlying Imjingang belt and the correlative Taean Formation, as well as SHRIMP isotopic ages of detrital zircons from meta-sandstones from the latter metamorphic marine turbidite sequences. We show that early Paleozoic isolated exotic terranes form part of the collision belt and were reworked in Permo-Triassic time. Age spectra of zircons from mature meta-sandstones in the Misan Formation (Imjingang Belt) and Taean Formation do not match the age distribution of the Gyeonggi Massif, to which both are usually assigned, as they show only subordinate 1.9–1.8 Ga and ∼2.5 Ga age modes but dominant 441–426 Ma and 978–919 Ma peaks. Much of the sediment appears to have been derived from distant, exotic middle Paleozoic and Early Neoproterozoic magmatic sources, not present in Gyeonggi or other Korean basement massifs. The youngest concordant zircon ages are: 394, 398 and 402 Ma, showing that both formations are at least of Early Devonian age. Terranes with a substratum with Early Neoproterozoic and Silurian-Devonian granitoids are present in the South Chinese Cathaysia Terrane and in the Qinling Terrane (Central China Orogen). Both formations may, hence, represent the submarine fan part of a routing system and a delta-shelf system originally situated in China. The Taean Formation and Imjingang Belt are thus exotic Paleozoic terranes tectonically emplaced in the Korean collision belt. Muscovite, biotite and amphibole from different units of the Imjingang Belt yielded tightly clustered Ar/Ar plateau ages between 255±1 and 249±1 Ma, dating fast cooling after peak temperature conditions. Slightly younger 243±1 and 240±1 Ma muscovite plateau ages in strongly retrogressed mylonites in the top of the Gyeonggi Mas-sif and 241–237 Ma age components (Taean Formation) point to collisional tectonism. Concordant 233–229 Ma isotopic ages of titanite, hornblende and mica in Hongseong zone and Taean Formation, and detrital muscovite in Jurassic Gimpo sandstones reveal a regional thermal event affecting large portions of the peninsula's crust, also manifested in widespread 237–226 Ma mantle-sourced Mg-rich potassic magmatism and associated mafic dykes truncating folds and tectonic foliations. The Late Triassic thermal pulse implies rapid advective-conductive asthenospheric heat transport promoted by extension and magmatic underplating during post-or late-collisional lower crust and uppermost mantle delamination and/or oceanic slab break-off. The efficiency of cooling is underlined by identical biotite (228±1 Ma) and hornblende (230±1 Ma) plateau ages in Hongseong amphibolites that are partly concordant with 243–229 Ma (average: ∼235 Ma) U–Pb zircon ages in the Gyeonggi Massif and the Hongseong zone, in the literature. This indicates that the Gyeonggi Massif is a Late Triassic core complex.