Unlocking The Complex Geology & Petroleum Systems; Efforts to Awakening The Sleeping Giant – A Prospectivity Rejuvenation Case Study of West Sebuku Block, South Makassar Basin, Indonesia

Significant uplift in the seismic imaging quality from the latest wide coverage of the Multi-Client Broadband PSDM 3D (MC3D) acquisition and processing, as well as cost and operational efficiencies, is an essential element to unlock the exploration potential of the under-explored South Makassar Basin. Many of exploration wells are usually drilled based on limited data, and structural closures are defined by sparse 2D seismic data and inadequate petroleum system models. Additional 3D seismic acquisition over the same area may enhance the structural imaging and provide a better understanding of the petroleum system. However, imaging the stratigraphic and structural complexities beneath carbonate platforms and steep slopes can be challenging and continued de-risk the plays. In 2018, Mubadala Petroleum requested PGS to acquire the first Multi-Client Broadband PSDM 3D survey in the South Makassar Basin. This MC3D survey has, for the first time, enabled imaging of well developed Eocene Platform carbonates and the Basement. Historical exploration and production activities with in the Basin have focused largely on the Oligocene aged carbonate debris flow deposits, as seen at Ruby Field. These new Eocene Platform carbonate and Basement plays have enabled Mubadala Petroleum to develop a significant exploration portfolio, revitalizing exploration activity in the Basin.

Epigenetic-Hydrothermal Fluorite Veins in a Phosphorite Deposit from Balaton Highland (Pannonian Basin, Hungary): Signatures of a Regional Fluid Flow System in an Alpine Triassic Platform

The middle Anisian extensional tectonics of the Neotethyan realm developed a small, isolated carbonate platform in the middle part of the Balaton Highland (western Hungary), resulted in the deposition of uranium-bearing seamount phosphorite on the top of the drowned platform and produced some epigenetic fluorite veins in the Middle Triassic sequence. The stable C-O isotope data of carbonates are shifted from the typical Triassic carbonate ranges, confirming the epigenetic-hydrothermal origin of veining. Primary fluid inclusions in fluorite indicate that these veins were formed from low temperature (85–169 °C) and high salinity NaCl + CaCl2 + H2O type (apparent total salinity: 15.91–22.46 NaCl wt%) hydrothermal fluids, similar to parent fluids of the Alpine-type Pb-Zn deposits. These findings indicate that the Triassic regional fluid circulation systems in the Alpine platform carbonates also affected the area of the Balaton Highland. This is also in agreement with the previously established palinspatic tectonic reconstructions indicating that the Triassic carbonate and basement units in the Balaton Highland area were a part of the Southern Alpine. Similar fluorite veining in phosphorite deposits is also known in the Southern Alpine areas (e.g., Monte San Giorgi, Italy). Raman spectroscopic analyses detected H2 gas in the vapor phase of the fluid inclusions and a defect-rich fluorite structure in violet to black colored growth zones. This unique phenomenon is assumed to be the result of interaction between the uranium-rich phosphorite and the parent fluids of the epigenetic fluorite veins.

AGGLUTINATED CONICAL FORAMINIFERA (ORBITOLINIDAE, COSKINOLINIDAE) FROM THE UPPER CRETACEOUS (CAMPANIAN) OF GREECE, WITH DESCRIPTION OF PARACOSKINOLINA KLOKOVAENSIS N. SP.

An assemblage of agglutinated conical foraminifera including Lepinoconus chiocchinii Cruz-Abad et al., Calveziconus lecalvezae Caus & Cornella, Paleodictyoconus sp., and Paracoskinolina klokovaensis n. sp. are described from the upper lower-middle Campanian of Klokova Mountain of the Gavrovo-Tripolitza Zone, SW continental Greece. With the presence of one rafter in the marginal zone, the new species P. klokovaensis compares to the Lower Cretaceous species Paracoskinolina arcuata (Arnaud-Vanneau) that is distinguished by its cylindroconical test morphology and much larger size. The assemblage occurs in inner platform carbonates associated with other foraminifers such as dicyclinids, and Accordiella conica Farinacci. Representatives of the genus Paracoskinolina were so far only reliably reported from the Upper Berriasian–Albian interval. This new record suggests that the genus either survived the larger benthic foraminifera extinction event associated with the Cenomanian – Turonian boundary anoxic event, or may be an example of an Elvis taxon or homoplasy.

Synchronous Eocene deformation recorded on either side of a major Miocene thrust bounding the Almyropotamos tectonic window in Evia, Greece

<p>Southern Evia in Greece exposes an inverted high pressure-low temperature (HP-LT) metamorphic sequence that has been loosely correlated with the Cycladic Blueschist Unit (CBU). On the island, the CBU is divided into the metavolcanic and ophiolitic Ochi Nappe and predominantly metacarbonate Styra Nappe. A lower-grade unit, the Almyropotamos Nappe, is exposed in the core of a N-S trending antiform and comprises Eocene platform carbonates overlain by metaflysch. The Almyropotamos Nappe occupies a tectonic window defined by the Evia Thrust, a brittle-ductile fault zone that emplaced the Ochi and Styra nappes atop the Almyropotamos Nappe. New multiple single-grain white mica total fusion <sup>40</sup>Ar/<sup>39</sup>Ar ages indicate that deformation occurred along the Evia Thrust at 25-23 Ma. White mica <sup>40</sup>Ar/<sup>39</sup>Ar data on either side of the tectonic window record Eocene dates between 40 and 32 Ma, consistent with previously published <sup>40</sup>Ar/<sup>39</sup>Ar dates and a single Rb-Sr age of c. 30 Ma. These ages broadly coincide with estimates for the timing of NE-directed thrusting of the Ochi Nappe over the Styra Nappe. Strain associated with thrusting localized as cylindrical folds in Styra marbles, with fold axes parallel to the stretching lineation and a clear strain gradient increasing toward the upper contact with the Ochi Nappe. The most prominent structures in the Ochi Nappe are a strong L-S fabric defined by acicular blue amphibole and type-3 refold structures with fold axes trending parallel to the NE-SW oriented stretching lineation. Whereas the Ochi Nappe and Styra Nappe locally preserve peak blueschist facies mineral assemblages, all three units commonly display evidence only for retrogressed initial HP-LT assemblages in the form of ferroglaucophane inclusions in albite porphyroblasts. Isochemical phase diagrams calculated in the Na<sub>2</sub>O-CaO-K<sub>2</sub>O-FeO-MgO-Al<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub>-H<sub>2</sub>O-TiO<sub>2</sub>±O<sub>2</sub> system support minimum peak metamorphic conditions of 12.5 ± 1.5 kbar and 465 ± 75 °C for an Ochi Nappe blueschist, and 6.0 ± 0.5 kbar and 315 ± 15 °C for an albite mica schist from the Evia Thrust. Peak P-T conditions for the Ochi Nappe support a metamorphic history more closely resembling that of the Lower Cycladic Blueschist Nappe, indicating that the entire section of the CBU exposed on Evia lies below the Trans-Cycladic Thrust. The Early Miocene ages from the Evia Thrust overlap with the proposed timing for the initiation of bivergent greenschist facies extension in the Cyclades. The remainder of the region, including high-strain corridors within individual nappes such as the Almyropotamos Thrust, uniformly records Eocene deformation ages. The similarity in <sup>40</sup>Ar/<sup>39</sup>Ar ages across the tectonic window contrasts with age relationships observed in similar tectonic packages on Lavrion, and suggests that regional scale deformation persisted until the Late Eocene before strain became localized in brittle-ductile corridors by the Early Miocene. </p>

Hooked on salt: Rethinking Alpine tectonics in Hallstatt (Eastern Alps, Austria)

Permian salt in the Hallstatt and neighboring salt structures of the Eastern Alps (Austria) crops out along with Triassic deep-water deposits that are at odds with the surrounding Triassic platform carbonates. The traditional interpretation of this juxtaposition is that the salt bodies were emplaced in the Late Jurassic as gravity nappes onto the carbonate platforms, in what has been considered to be the earliest orogenic event in the Eastern Alps. Here we describe for the first time a world-class outcrop of halokinetic sequences in Triassic platform carbonates flanking the Hallstatt diapir. Combining this with other outcrop evidence, we prove that the Hallstatt diapir grew passively during the Triassic, surrounded by carbonate platforms, and extruded to the seabed during the Jurassic. The development of the Hallstatt diapir in a platform setting disproves its emplacement as a gravity-driven nappe, proves the relevance of salt tectonics in the Mesozoic development of the Eastern Alps, and challenges the existence of a Late Jurassic Alpine orogenic event.