Academic literature on the topic 'Overprinting relationships'
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Journal articles on the topic "Overprinting relationships"
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Hemingway, Jordon D., Haley Olson, Alexandra V. Turchyn, Edward T. Tipper, Mike J. Bickle, and David T. Johnston. "Triple oxygen isotope insight into terrestrial pyrite oxidation." Proceedings of the National Academy of Sciences 117, no. 14 (March 25, 2020): 7650–57. http://dx.doi.org/10.1073/pnas.1917518117.
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The mass-independent minor oxygen isotope compositions (Δ′17O) of atmospheric O2andCO2are primarily regulated by their relative partial pressures,pO2/pCO2. Pyrite oxidation during chemical weathering on land consumesO2and generates sulfate that is carried to the ocean by rivers. The Δ′17O values of marine sulfate deposits have thus been proposed to quantitatively track ancient atmospheric conditions. This proxy assumes directO2incorporation into terrestrial pyrite oxidation-derived sulfate, but a mechanistic understanding of pyrite oxidation—including oxygen sources—in weathering environments remains elusive. To address this issue, we present sulfate source estimates and Δ′17O measurements from modern rivers transecting the Annapurna Himalaya, Nepal. Sulfate in high-elevation headwaters is quantitatively sourced by pyrite oxidation, but resulting Δ′17O values imply no direct troposphericO2incorporation. Rather, our results necessitate incorporation of oxygen atoms from alternative,17O-enriched sources such as reactive oxygen species. Sulfate Δ′17O decreases significantly when moving into warm, low-elevation tributaries draining the same bedrock lithology. We interpret this to reflect overprinting of the pyrite oxidation-derived Δ′17O anomaly by microbial sulfate reduction and reoxidation, consistent with previously described major sulfur and oxygen isotope relationships. The geologic application of sulfate Δ′17O as a proxy for pastpO2/pCO2should consider both 1) alternative oxygen sources during pyrite oxidation and 2) secondary overprinting by microbial recycling.
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Williams, Harold, and M. A. J. Piasecki. "The Cold Spring Melange and a possible model for Dunnage–Gander zone interaction in central Newfoundland." Canadian Journal of Earth Sciences 27, no. 8 (August 1, 1990): 1126–34. http://dx.doi.org/10.1139/e90-117.
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Structural relationships at Cold Spring Pond and the recognition of ophiolitic melange bear on the important questions of timing and style of structural superpositioning of Dunnage Zone rocks above Gander Zone rocks in central Newfoundland. The latest models emphasize ductile shear boundaries and orogen-parallel movements. Previous models proposed west-to-east or head-on obduction of Dunnage ophiolitic rocks across the Gander Zone.At the Dunnage (Exploits Subzone) – Gander (Meelpaeg Subzone) boundary at Cold Spring Pond, discrete, outcrop-size ultramafic blocks and smaller quartzite blocks are randomly distributed, and they are surrounded by, or are embedded in, homogeneous black graphitic shale or phyllite. The ultramafic blocks are typical of nearby Early Ordovician Dunnage ophiolite suites, the quartzite blocks are typical of adjacent Early Ordovician or earlier Gander clastic rocks, and the matrix black shales are similar to those of Middle or Early Ordovician age that occur throughout central Newfoundland. This chaotic mixture of almost coeval lithologies at Cold Spring Pond is interpreted as an olistostromal melange; the Cold Spring Melange. It resembles melanges that are dated as Ordovician elsewhere in Newfoundland.The Cold Spring Melange is overprinted by the full range of structures and metamorphic effects evident in adjacent rocks of the Exploits (Dunnage) and Meelpaeg (Gander) subzones. These include the development of lineations, cleavages, schistosities, zones of ductile shearing, regional metamorphism, and contact metamorphism. The oldest of these effects are interpreted as Silurian, based on isotopic dating in southern Newfoundland.The formation of olistostromal, ophiolitic melange implies disruption of the oceanic tract (Exploits Subzone of the Dunnage Zone), and in the case of the Cold Spring example, juxtapositioning or transport of Exploits Subzone ophiolite suites against or across the supracrustal rocks of the Meelpaeg Subzone (Gander Zone). The age and provenance of Cold Spring components, lack of post-Ordovician components, overprinting structural relationships, and comparison with other Newfoundland melanges all support an Ordovician age of formation. Overprinting relationships indicate that major ductile shears at other Dunnage–Gander zone boundaries postdate initial Dunnage–Gander superpositioning.
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ALSOP, G. I., R. BRYSON, and D. H. W. HUTTON. "Ductile transpression and localization of deformation along tectonic boundaries in the Caledonides of northwestern Ireland." Geological Magazine 135, no. 5 (September 1998): 699–718. http://dx.doi.org/10.1017/s0016756898001265.
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Orogenesis is increasingly interpreted in terms of strain focusing, localization and partitioning processes. Such heterogeneous deformation is considered a consequence of the tectonic framework, with pre-existing structural and stratigraphic variability providing inherent zones of crustal weakness. Detailed structural investigation of Neoproterozoic Dalradian metasediments in the Glencolumbkille region, northwest Ireland, enables patterns of reworking and strain localization to be assessed in terms of four overprinting ductile deformation episodes. A well-defined and intricate Dalradian stratigraphy provides readily distinguishable markers which not only focus deformation along marked rheological boundaries, but also aid in the definition and identification of resultant geometries. Overall structural and stratigraphic relationships show that whilst D1 was not associated with major structures, D2 is related to north–northeast directed folding and ductile thrusting resulting in a major phase of crustal thickening and almandine-amphibolite facies metamorphism. Structures generated during D2 deformation subsequently became the locus of intense D3 strain and were reactivated in an oblique sense associated with south or southwest directed translations. Local overprinting relationships clearly demonstrate S2 fabrics being transposed by S3 resulting in a composite foliation over large areas. Similarly, the L2 mineral lineation is abruptly transposed by L3 over relatively small distances indicating high D3 strain gradients and the susceptibility of lineations to reworking. The final stage of ductile deformation (D4) which was increasingly localized and focused into earlier (D2−D3) high strain zones, is marked by a pronounced phase of sinistral transpression associated with clockwise cleavage and minor fold transection of northwest verging upright folds. Sinistral shear is strongly partitioned in to the steep limbs of mesoscopic F4 folds. The detailed investigation of structures generated within such multiply deformed and reworked zones provides evidence of both the kinematic and tectonic evolution of regional deformation systems.
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Kellett, R. L., and B. Rivard. "Characterization of the Benny deformation zone, Sudbury, Ontario." Canadian Journal of Earth Sciences 33, no. 9 (September 1, 1996): 1256–67. http://dx.doi.org/10.1139/e96-095.
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Remote sensing imagery and geophysical data are well known as valuable tools for reconnaissance mapping in unknown areas, but they can also be used to reinterpret existing regional geological maps. A combination of airborne magnetic data and synthetic aperture radar images, at both a regional and a detailed scale, have been used to identify a wrench-fault system on the Canadian Shield north of the Sudbury structure. The 3–4 km wide deformation zone comprises a set of subparallel vertical faults bounding blocks of Archean granites, Archean metavolcanics of the Benny greenstone belt, and Paleoproterozoic metasediments of the Huronian supergroup. Using high-resolution airborne radar and magnetic data, the fault zone is found to extend for 40 km along the southern margin of the Benny greenstone belt. The wrench-fault system may have been tectonically active during several episodes throughout the Proterozoic. An interpretation of these data, supported by additional field mapping, indicates that the 1240 Ma Sudbury dyke swarm has been intruded through the deformation zone after its most active period of movement. Overprinting of Sudbary impact breccia at the southern edge of the deformation zone suggests that some movement occurred on the faults postdating the 1850 Ma meteorite impact. Lineaments that correlate spatially with the wrench-fault system can be traced across the southern Superior Province and the Cobalt Embayment on the regional images. However, more high-resolution studies are required to establish the same overprinting relationships along the length of the lineaments.
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CLARKE, G. L., and R. POWELL. "Proterozoic granulite facies metamorphism in the southeastern Reynolds Range, central Australia: geological context, P?T path and overprinting relationships." Journal of Metamorphic Geology 9, no. 3 (May 1991): 267–81. http://dx.doi.org/10.1111/j.1525-1314.1991.tb00522.x.
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Xu, Wen-Liang, Fu-Ping Pei, Feng Wang, En Meng, Wei-Qiang Ji, De-Bin Yang, and Wei Wang. "Spatial–temporal relationships of Mesozoic volcanic rocks in NE China: Constraints on tectonic overprinting and transformations between multiple tectonic regimes." Journal of Asian Earth Sciences 74 (September 2013): 167–93. http://dx.doi.org/10.1016/j.jseaes.2013.04.003.
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Mancktelow, Neil, and Giorgio Pennacchioni. "Intermittent fracturing in the middle continental crust as evidence for transient switching of principal stress axes associated with the subduction zone earthquake cycle." Geology 48, no. 11 (July 21, 2020): 1072–76. http://dx.doi.org/10.1130/g47625.1.
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Abstract In the Neves area, eastern Alps, fractures that localized shear zones in middle continental crust above the Alpine megathrust are commonly oriented at a high angle to the inferred long-term shortening direction. Fractures show a segmentation geometry and, locally, a discernible offset, indicating movement opposite to the sense of subsequent ductile shear and implying a switch of principal stress axes σ1 and σ3 during fracturing. We propose that this repeated switch, demonstrated by overprinting relationships and different degrees of fracture reactivation, was due to sporadic co-seismic to early post-seismic rebound in the upper plate of the Alpine continental collision system. Fracturing occurred intermittently in the weak midcrustal rocks due to seismic stress release at high transient strain rates and pore-fluid pressures. Widespread transient fracturing in the hanging wall of the Alpine megathrust regionally controls the orientation of ductile shear zones in the middle crust, as well as the emplacement of magmatic dikes.
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Corrigan, David, Nicholas G. Culshaw, and Jim K. Mortensen. "Pre-Grenvillian evolution and Grenvillian overprinting of the Parautochthonous Belt in Key Harbour, Ontario: U–Pb and field constraints." Canadian Journal of Earth Sciences 31, no. 3 (March 1, 1994): 583–96. http://dx.doi.org/10.1139/e94-051.
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The Parautochthonous Belt in the region of Key Harbour, Ontario, is composed of Early Proterozoic migmatitic para- and orthogneiss and Mid-Proterozoic granitoids, which were reworked during the Grenville orogeny. Grenvillian deformation is localized into anastomosing arrays of high-strain shear zones enclosing elongate bands and lozenges of rock subjected to lower and near-coaxial strain. Crosscutting relationships preserved in the low-strain domains document two pre-Grenvillian plutonic and tectonometamorphic events, which are bracketed in age by U–Pb zircon geochronology. A 1694 Ma leucogranite intrudes, and provides a minimum age for, high metamorphic grade gneisses formed during an earlier tectonometamorphic event (D1–M1). The leucogranite was intruded by mafic dykes, deformed, and metamorphosed at uppermost amphibolite facies during D2–M2, before the emplacement of Mid-Proterozoic granitoids at ca. 1450 Ma. Following the emplacement of gabbro dykes and pods at ca. 1238 Ma, the area was overprinted by granulite to uppermost amphibolite facies metamorphism (Grenvillian), for which monazites provide a minimum age of ca. 1035 Ma. Titanite U–Pb ages of 1003 – 1004 Ma record cooling through 600 °C. A regionally important swarm of east–west-trending posttectonic pegmatite dykes dated by U–Pb zircon at 990 Ma provides a minimum age for Grenvillian ductile deformation. The present data support the contention that the Parautochthonous Belt in the Key Harbour area consists in part of reworked midcontinental crust of Early to Mid-Proterozoic age.
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Feng, Rui, Jianzhong Fan, and Robert Kerrich. "Noble metal abundances and characteristics of six granitic magma series, Archean Abitibi Belt, Pontiac Subprovince; relationships to metallogeny and overprinting of mesothermal gold deposits." Economic Geology 88, no. 6 (October 1, 1993): 1376–401. http://dx.doi.org/10.2113/gsecongeo.88.6.1376.
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Wilson, Matthew Coffie, Chiri G. Amedjoe, and Simon K. Y. Gawu. "STRUCTURES OF BIRIMIAN AND TARKWAIAN ROCKS AT NORTH-WEST NEW DROBO – IMPLICATION ON DEFORMATION." Malaysian Journal of Geosciences 6, no. 1 (2022): 36–44. http://dx.doi.org/10.26480/mjg.01.2022.36.44.
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This research leads to identifying the microstructures, the deformation episodes (D) and foliation grades (S) of rocks in the study area. Different geological structures such as shear zones, foliations, micro-faults, crack-seal events, etc. have been identified in the study area. Different phases of deformation episodes and foliation grades have been studied to determine the deformation environments. Senses of shear such as dextral, CS, and CS’ as well as antithetic and synthetic micro-faults and boudins may be identified at the north-west New Drobo. Three (3) main deformational (D) events and foliation grades (S) in both the Tarkwaian sandstones and Birimian volcanic rocks may be identified as D1, D2 and D3 as well as S1, S2 and S3. Recrystallization of quartz and feldspar through bulging (BLG), subgrain boundary rotation (SBR) and grain boundary migration (GBM) have been observed at the study area. The overprinting relationships in the Birimian Supergroup may be identified with three (3) different deformational phases. The first deformation (D1) defines the formation of a vertical shortening, whilst the second deformation (D2) defines oblique shortening. Moreover, the third deformation (D3) is due to high strain rate causing brittle faulting.
Dissertations / Theses on the topic "Overprinting relationships"
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Sidor, Miroslav. "The origin of black rock alteration overprinting iron-rich sediments and its genetic relationship to disseminated polymetallic sulphide ores, Lou Lake, Northwest Territories, Canada." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0017/MQ58084.pdf.
Full textBook chapters on the topic "Overprinting relationships"
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Ross, Colin, Jeremy P. Richards, and Ross Sherlock. "Geology, Alteration, and Geochronology of the Cerro Vetas Porphyry Gold-Copper Deposit, Middle Cauca Belt, Colombia." In Tectonomagmatic Influences on Metallogeny and Hydrothermal Ore Deposits: A Tribute to Jeremy P. Richards (Volume II), 311–32. Society of Economic Geologists, 2021. http://dx.doi.org/10.5382/sp.24.17.
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Abstract The Cerro Vetas porphyry deposit is part of the Titiribi district of the Middle Cauca porphyry-epithermal belt of western Colombia. The Cerro Vetas porphyry stock consists of a premineral diorite intruded by a late-mineral quartz monzonite, with intrusion and contact breccias. These units intrude pre-Cenozoic basement metabasalts and schists, Oligocene-Miocene Amagá Formation sedimentary rocks with intercalated andesite flows. Two phases of potassic alteration are recognized, a biotite-dominant phase in the diorite, and secondary K-feldspar in the quartz-monzonite intrusion. An overprinting and grade destructive, calcic-sodic alteration (actinolite + albite ± magnetite) affects both porphyries. Biotite alteration is overprinted by weak-moderate phyllic alteration in the upper 100 m in the deposit. Below 100 m, phyllic alteration assemblages are constrained to structural zones. Mineralization is dominated by a chalcopyrite-gold-pyrite assemblage associated with biotite that is hosted in a truncated stockwork in the apical portion of the deposit with metal ratios typical of a gold-rich copper-gold porphyry. The intrusions were dated, using U-Pb in zircon laser ablation inductively coupled plasma-mass spectroscopy, to between 7.65 to 7.24 Ma, consistent with other deposits in the Middle Cauca belt. Lithologic, alteration, and stratigraphic relationships at the deposit suggest that the Cerro Vetas porphyry was emplaced at shallow depths and that the upper portion of the deposit has been eroded.
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Eusden, J. Dykstra, Ian W. Hillenbrand, Elizabeth Folsom, Thorn Merrill, Kurt Niiler, and Audrey Wheatcroft. "Evolution of the Bronson Hill arc and Central Maine basin, northern New Hampshire to western Maine: U-Pb zircon constraints on the timing of magmatism, sedimentation, and tectonism." In Laurentia: Turning Points in the Evolution of a Continent. Geological Society of America, 2022. http://dx.doi.org/10.1130/2022.1220(26).
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ABSTRACT The Ordovician Bronson Hill arc and Silurian–Devonian Central Maine basin are integral tectonic elements of the northern Appalachian Mountains (USA). However, understanding the evolution of, and the relationship between, these two domains has been challenging due to complex field relationships, overprinting associated with multiple phases of Paleozoic orogenesis, and a paucity of geochronologic dates. To constrain the nature of this boundary, and the tectonic evolution of the northern Appalachians, we present U-Pb zircon dates from 24 samples in the context of detailed mapping in northern New Hampshire and western Maine. Collectively, the new geochronology and mapping results constrain the timing of magmatism, sedimentation, metamorphism, and deformation. The Bronson Hill arc formed on Gondwana-derived basement and experienced prolonged magmatic activity before and after a ca. 460 Ma reversal in subduction polarity following its accretion to Laurentia in the Middle Ordovician Taconic orogeny. Local Silurian deformation between ca. 441 and 434 Ma may have been related to the last stages of the Taconic orogeny or the Late Ordovician to early Silurian Salinic orogeny. Silurian Central Maine basin units are dominated by local, arc-derived zircon grains, suggestive of a convergent margin setting. Devonian Central Maine basin units contain progressively larger proportions of older, outboard, and basement-derived zircon, associated with the onset of the collisional Early Devonian Acadian orogeny at ca. 410 Ma. Both the Early Devonian Acadian and Middle Devonian to early Carboniferous Neoacadian orogenies were associated with protracted amphibolite-facies metamorphism and magmatism, the latter potentially compatible with the hypothesized Acadian altiplano orogenic plateau. The final configuration of the Jefferson dome formed during the Carboniferous via normal faulting, possibly related to diapirism and/or ductile thinning and extrusion. We interpret the boundary between the Bronson Hill arc and the Central Maine basin to be a pre-Acadian normal fault on which dip was later reversed by dome-stage tectonism. This implies that the classic mantled gneiss domes of the Bronson Hill anticlinorium formed relatively late, during or after the Neoacadian orogeny, and that this process may have separated the once-contiguous Central Maine and Connecticut Valley basins
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McDivitt, Jordan A., Steffen G. Hagemann, Matthew S. Baggott, and Stuart Perazzo. "Chapter 12: Geologic Setting and Gold Mineralization of the Kalgoorlie Gold Camp, Yilgarn Craton, Western Australia." In Geology of the World’s Major Gold Deposits and Provinces, 251–74. Society of Economic Geologists, 2020. http://dx.doi.org/10.5382/sp.23.12.
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Abstract The Kalgoorlie gold camp in the Yilgarn craton of Western Australia comprises the supergiant Golden Mile and the smaller Mt. Charlotte, Mt. Percy, and Hidden Secret deposits. Since the camp’s discovery in 1893, ~1,950 metric tons (t) of Au have been produced from a total estimated endowment of ~2,300 t. The camp is located within Neoarchean rocks of the Kalgoorlie terrane, within the Eastern Goldfields superterrane of the eastern Yilgarn craton. Gold mineralization is distributed along an 8- × 2-km, NNW-trending corridor, which corresponds to the Boulder Lefroy-Golden Mile fault system. The host stratigraphic sequence, dated at ca. 2710 to 2660 Ma, comprises lower ultramafic and mafic lava flow rocks, and upper felsic to intermediate volcaniclastic, epiclastic, and lava flow rocks intruded by highly differentiated dolerite sills such as the ca. 2685 Ma Golden Mile Dolerite. Multiple sets of NNW-trending, steeply dipping porphyry dikes intruded this sequence from ca. 2675 to 2640 Ma. From ca. 2685 to 2640 Ma, rocks of the Kalgoorlie gold camp were subjected to multiple deformation increments and metamorphism. Early D1 deformation from ca. 2685 to 2675 Ma generated the Golden Mile fault and F1 folds. Prolonged sinistral transpression from ca. 2675 to 2655 Ma produced overprinting, NNW-trending sets of D2-D3 folds and faults. The last deformation stage (D4; < ca. 2650 Ma) is recorded by N- to NNE-trending, dextral faults which offset earlier structures. The main mineralization type in the Golden Mile comprises Fimiston lodes: steeply dipping, WNW- to NNW-striking, gold- and telluride-bearing carbonate-quartz veins with banded, colloform, and crustiform textures surrounded by sericite-carbonate-quartz-pyrite-telluride alteration zones. These lodes were emplaced during the earlier stages of regional sinistral transpression (D2) as Riedel shear-type structures. During a later stage of regional sinistral transpression (D3), exceptionally high grade Oroya-type mineralization developed as shallowly plunging ore shoots with “Green Leader” quartz-sericite-carbonate-pyrite-telluride alteration typified by vanadium-bearing muscovite. In the Hidden Secret orebody, ~3 km north-northwest of the Golden Mile, lode mineralization is a silver-rich variety characterized by increased abundance of hessite and petzite and decreased abundance of calaverite. At the adjacent Mt. Charlotte deposit, the gold-, silver-, and telluride-bearing lodes become subordinate to the Mt. Charlotte-type stockwork veins. The stockwork veins occur as planar, 2- to 50-cm thick, auriferous quartz-carbonate-sulfide veins that define steeply NW- to SE-dipping and shallowly N-dipping sets broadly coeval with D4 deformation. Despite extensive research, there is no consensus on critical features of ore formation in the camp. Models suggest either (1) distinct periods of mineralization over a protracted, ca. 2.68 to 2.64 Ga orogenic history; or (2) broadly synchronous formation of the different types of mineralization at ca. 2.64 Ga. The nature of fluids, metal sources, and mineralizing processes remain debated, with both metamorphic and magmatic models proposed. There is strong evidence for multiple gold mineralization events over the course of the ca. 2.68 to 2.64 orogenic window, differing in genesis and contributions from either magmatic or metamorphic ore-forming processes. However, reconciling these models with field relationships and available geochemical and geochronological constraints remains difficult and is the subject of ongoing research.
Conference papers on the topic "Overprinting relationships"
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Dewi, V. T. "Carbonate Pore System Characterization, a Study Case from Drowning Cap Sequence in VITA Field, ExxonMobil Block Cepu Limited (EMCL)." In Indonesian Petroleum Association 44th Annual Convention and Exhibition. Indonesian Petroleum Association, 2021. http://dx.doi.org/10.29118/ipa21-g-46.
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Carbonate rocks are known as one of the principal reservoir rocks in the world due to their good porosity and permeability. However, the heterogeneity of carbonate reservoir quality is difficult to predict. Variability of diagenetic processes overprinting carbonate depositional texture has resulted in a complex carbonate pore system. As a consequence, this complexity results in a harder reservoir characterization and also a discrepancy between actual and model properties, that leads to a harder history match in reservoir simulation. By presenting a study case from the Drowning Cap Sequence in the VITA Reservoir Block Cepu, this paper will present a comprehensive approach which focusing on characterization of a carbonate pore system for optimum geomodel, simulation and surveillance. This approach utilized static data of 100 ft total of cores, ±500 thin sections, well, and image logs. The study has resulted in definition of four Carbonate Reservoir Rock Types (RRT) which were clustered using the analysis of carbonate dominant pore types and the porosity-permeability relationship. Results revealed that there are 4 RRTs observed as follows: (1) RRT 1 – Touching Vugs-dominated, with high porosity and permeability, (2) RRT 2 – Interparticle- and Moldic-dominated, with moderate to high porosity value and lower permeability than RRT 1, (3) RRT 3 – Microfracture-dominated, with very low porosity value and low to moderate permeability, and (4) RRT 4 – Minimum Dissolution, with very low porosity and permeability value, lower than RRT 3. Each RRT was integrated with well and image logs to understand its characteristics and behavior. Ultimately, all data were integrated, analyzed and successfully captured carbonate reservoir quality variation, distribution and depositional evolution along with overprinted diagenetic processes vertically and laterally. This approach successfully captured carbonate heterogeneity which ultimately will be useful to develop better geological and reservoir simulation models after being integrated with dynamic data and observations.