Upper Devonian and Lower–Middle Mississippian strata of the North American midcontinent are ubiqu... more Upper Devonian and Lower–Middle Mississippian strata of the North American midcontinent are ubiquitously fine-grained and silt-rich, comprising both so-called shale as well as argillaceous limestone (or calcareous siltstone) that accumulated in the Laurentian epeiric sea. Although long recognized as recording marine deposition, the origin and transport of the fine-grained siliciclastic material in these units remains enigmatic because they do not connect to any proximal deltaic feeder systems. Here, we present new data on grain size, whole-rock geochemistry, mineralogy, and U-Pb detrital-zircon geochronology from units across Oklahoma; we then integrate these data with models of surface wind circulation, refined paleogeographic reconstructions, and correlations from the greater midcontinent to test the hypothesis that wind transported the siliciclastic fraction to the marine system. The exclusively very fine silt to very fine sand grain size, clear detrital origin, widespread distri...
Each of the catchment areas of Borneo's major river systems has distinct differences in their bed... more Each of the catchment areas of Borneo's major river systems has distinct differences in their bedrock lithologies. As the provenance for the sediments delivered to the deepwater depositional systems, these lithological variations in the hinterland are an important consideration when predicting high quality turbidite reservoirs as they influence compaction and diagenesis. This paper examines these issues for the Baram, Sandakan, Tarakan, and Kutei Basins. Additionally, the role of hinterland bedrock composition of the Baram and Padas Rivers is considered in terms of influencing along strike changes in the structural style of the Northwest Borneo deepwater fold and thrust belts.
Middle Miocene to Pliocene sedimentation on the NW Borneo margin has been interpreted as the prod... more Middle Miocene to Pliocene sedimentation on the NW Borneo margin has been interpreted as the product of one relatively large deltaic system, the Champion Delta. However, several lines of evidence indicate that the Champion system was not a simple, large delta; its drainage basin was too small, fluvial outcrops indicate multiple, relatively small rivers and outcrop studies indicate the same facies associations as the diverse, modern depositional systems. The number and location of rivers reaching the shoreline changed as rapidly subsiding footwall synclines, episodically active inversion anticlines and growth faults created an evolving structurally-generated topography that not only controlled drainage pathways, but also segregated Champion strata into thick, wave-dominant and tide-dominant successions. Although the principal rivers within the Champion system, the Limbang, Padas and Trusan Rivers, transport significant loads of coarse sediment, the intermittent proximal ponding of sand in local basins, as is currently occurring in Brunei Bay, resulted in a variable delivery of sand to the shelf edge. The number and distribution of shelf edge canyons also changed with time. Consequently, the spatial and temporal distribution of deepwater sand accumulations sourced from the Champion system are not solely related to relative sea level fluctuations; such accumulations should be smaller and more scattered than those sourced from a large shelf edge delta. Because the catchments of the Champion system's principal rivers represent different provenances, the system's deepwater sands may carry the signal of specific rivers. For example, mineralogical contrasts between in the main reservoir sands of the deepwater Gumusut and Kikeh fields suggest that the relative contributions of the principal rivers shifted with time with the Trusan and Limbang Rivers dominating sand supply for the youngest reservoirs at Gumusut.
Pinta, one of the northern islands in the Galapagos archipelago, is the top of a shield volcano w... more Pinta, one of the northern islands in the Galapagos archipelago, is the top of a shield volcano which became emergent ~0.7 m.y. ago. A regional north-northwest-trending fracture system influenced the locus of volcanisin. Pinta's geologic development can be divided into an older, shield stage and a younger, fissure stage. Each stage produced a similar, yet distinct, series of evolved olivine tholeiites (magnesium number = : 52). The shield series underwent some additional shallow-level fractionation in a periodically replenished chamber. Rare-earth-element data indicate that the mantle source for both of the series has residual garnet. Higher concentrations of incompatible trace elements in the fissure series imply a lower degree of partial melting. 143 Nd/ 144 Nd and ^Sr/^Sr ratios suggest that both series have an enriched, hotspot-type source. Despite close proximity to the Galapagos spreading ridge, Pinta's lavas lack features characteristic of mid-ocean ridge basalts. The isotopic and rare-earth-element data from Pinta and the other northern islands are consistent with previous models for the Galapagos spreading ridge, which require north-south axially directed transfer of enriched asthenosphere and/or melts from the Galapagos hotspot to the Galapagos Ridge.
The Mississippian Meramecian Series in the STACK (Sooner Trend Anadarko [Basin] Canadian Kingfish... more The Mississippian Meramecian Series in the STACK (Sooner Trend Anadarko [Basin] Canadian Kingfisher counties) and laterally equivalent units within the Caney Shale and Sycamore Limestone in the Arbuckle Mountains and Ardmore Basin (SCOOP: South Central Oklahoma Oil Province) consist of a succession of interbedded silty limestones, quartz-rich calcareous siltstones, argillaceous siltstones, and organic-rich mudstones that form conventional and unconventional reservoirs. Core, well-log, and outcrop data are integrated to develop a regional stratigraphic framework from the STACK to SCOOP, characterize the depositional environments, and map the distribution of organic-rich facies within the Meramecian Series. In the STACK , the Meramec was divided into 7 shallowing-upward sequence-stratigraphic cycles or zones. The cycles are capped by shales interpreted as marine-flooding surfaces. In the STACK area, the Meramec sediments were deposited on a gentle ramp and are interpreted to record of...
A key consideration in tectonic models for SE Asia and opening of the South China Sea is the role... more A key consideration in tectonic models for SE Asia and opening of the South China Sea is the role that the West Baram and Tinjar Lines of NW Borneo may have played in accommodating the motion of crustal blocks displaced from Asia following India's collision. There are few studies that focus on these "lines". Using onshore geological studies and offshore seismic data to address the origin and tectonic significance of these, this paper concludes that rather than a major transform boundary between Luconia and the Dangerous Grounds, the West Baram Line marks the boundary between domains of continental crust that underwent differential extension in the Eocene. The Baram Basin is underlain by hyperextended continental crust on the NE side of the Baram Line. The strong contrast in the geological features across the Tinjar and West Baram Lines likely reflects ancient differences in crustal rheology with Luconia being the more rigid block. Although lack of significant strike slip faulting along the West Baram Line poses problems for tectonic models in which a wide proto-South China Sea is subducted beneath NW Borneo, intra-plate deformation, such as partial inversion of the Dangerous Grounds rift, offers a potential mechanism to mass balance blocks displaced from Asia with the reduced strike slip motion along the West Baram Line.
Tectonic models for Borneo's Cenozoic evolution differ in several aspects, particularly in the ex... more Tectonic models for Borneo's Cenozoic evolution differ in several aspects, particularly in the extent to which they include paleomagnetic data suggestive of strong counterclockwise rotation between 30 and 10 Ma. Key areas are undersampled. We present the results of a paleomagnetic study of Eocene to Early Miocene sandstones from northwest Sabah, principally from the Crocker Formation. We obtained reliable site means from 11 locations along a 250 km northeast-southwest transect using thermal demagnetization to isolate characteristic remanent magnetization (ChRM) directions. The Crocker Formation sandstones are pervasively remagnetized; pyrrhotite dominates the ChRM signal. Locations can be grouped into different domains on the basis of the relative sense of rotation about a vertical axis. Mean ChRM directions for seven locations between Kota Kinabalu and Keningau (declination, dec 12°-19°; inclination, inc-22°-23°) indicate minor clockwise rotation and modest tilting, whereas two locations near Tenom (dec 321°-345°, inc-6°-24°) record counterclockwise rotation and modest tilting. Although we cannot precisely date the age of remagnetization, the results of fold tests from 4 locations, interpreted within the regional structural framework, strongly indicate that remagnetization occurred between 35 and 15 Ma, the waning stages of the Sarawak orogeny to an early phase of the Sabah orogeny. Our results pose serious diffi culties for current tectonic models in which Borneo rotates 50° counterclockwise as a rigid block between 30 and 10 Ma. With respect to prior paleomagnetic studies, we suspect that an early episode of strong regional counterclockwise rotation (before 35 Ma) was over-printed not only by differential clockwise rotation of crustal blocks during opening of the South China Sea (32-23 Ma), but also locally by a younger (after 10 Ma) counterclockwise rotation.
The Energy Citations Database (ECD) provides access to historical and current research (1948 to t... more The Energy Citations Database (ECD) provides access to historical and current research (1948 to the present) from the Department of Energy (DOE) and predecessor agencies.
SEG Technical Program Expanded Abstracts 1993, 1993
Page 1. Northern New Guinea Hydrocarbon Potential: New Constraints from Tectonic Subsidence Analy... more Page 1. Northern New Guinea Hydrocarbon Potential: New Constraints from Tectonic Subsidence Analysis and Seismic Stratigraphy John D. Pigott, University of Oklahoma; Douglas G. Neese*, Maxus Energy Corp.; Andrew B. Cullen, Pecten International SS4.6 ...
... are rather cool and suggest a fore-arc rather than back-arc setting, although thermal disequi... more ... are rather cool and suggest a fore-arc rather than back-arc setting, although thermal disequilibrium within the rapidly deposited, thick Wewak se ... Unless future work can demonstrate oil-prone source rocks or active oil seeps, the Ramu basin can be regarded as a gas-prone ...
The Usun Apau plateau lies in a remote area of Sarawak along the Tinjar Line, which defines the o... more The Usun Apau plateau lies in a remote area of Sarawak along the Tinjar Line, which defines the onshore part of a suture between the Luconia and Dangerous Grounds blocks. Reconnaissance studies in late 1950s established that the plateau is composed of a bimodal suite of young volcanic rocks, but no further work exists to constrain the age and petrogenesis of the Usun Apau volcanics. We present and discuss new data from a suite of volcanic rocks recently collected from the Usun Apau region. These data include 40 Ar-39 Ar age dates of mineral separates, major and trace element geochemistry, and Sr, Nd, Pb isotope geochemistry. The Usun Apau plateau is constructed largely of dacite and andesite erupted between 3.9 and 4.1 Ma. Minor basaltic dikes and flows (ca. 2.1 Ma) represent a distinctly younger episode of volcanism that is similar in age and character to the Linau Balui basalts about 100 km SE of the plateau. Although the trace element and isotopic suites from both areas indicate the parental melts were generated from a garnet-bearing, LILE-enriched, non-HIMU OIB-like mantle source, depletion in the HREEs and a negative Nb anomaly impart some characteristics of an island arc-type source contribution. The Usun Apau and Linau Balui volcanics are too young to be directly linked to subduction beneath Borneo; indicating a source region possibly modified by an older episode of subduction. Sr, Nd, Pb inter-isotope correlations plot within the same arrays as Pliocene basalts from the Southern Sulu Arc (500 km NE) which suggests much of northern and central Borneo is underlain by similar lithosphere. Assimilationfractional crystallization modeling indicates that differentiation of the Usun Apau dacite magmas included assimilation of continental crust with very low 143 Nd/ 144 Nd. Modeling different basement compositions as contaminants yielded non-unique results. Triassic Malay granite and different Archean granites represent plausible types of assimilants; whereas crust of Dangerous Grounds and Kontum Plateau do not.
Upper Devonian and Lower–Middle Mississippian strata of the North American midcontinent are ubiqu... more Upper Devonian and Lower–Middle Mississippian strata of the North American midcontinent are ubiquitously fine-grained and silt-rich, comprising both so-called shale as well as argillaceous limestone (or calcareous siltstone) that accumulated in the Laurentian epeiric sea. Although long recognized as recording marine deposition, the origin and transport of the fine-grained siliciclastic material in these units remains enigmatic because they do not connect to any proximal deltaic feeder systems. Here, we present new data on grain size, whole-rock geochemistry, mineralogy, and U-Pb detrital-zircon geochronology from units across Oklahoma; we then integrate these data with models of surface wind circulation, refined paleogeographic reconstructions, and correlations from the greater midcontinent to test the hypothesis that wind transported the siliciclastic fraction to the marine system. The exclusively very fine silt to very fine sand grain size, clear detrital origin, widespread distri...
Each of the catchment areas of Borneo's major river systems has distinct differences in their bed... more Each of the catchment areas of Borneo's major river systems has distinct differences in their bedrock lithologies. As the provenance for the sediments delivered to the deepwater depositional systems, these lithological variations in the hinterland are an important consideration when predicting high quality turbidite reservoirs as they influence compaction and diagenesis. This paper examines these issues for the Baram, Sandakan, Tarakan, and Kutei Basins. Additionally, the role of hinterland bedrock composition of the Baram and Padas Rivers is considered in terms of influencing along strike changes in the structural style of the Northwest Borneo deepwater fold and thrust belts.
Middle Miocene to Pliocene sedimentation on the NW Borneo margin has been interpreted as the prod... more Middle Miocene to Pliocene sedimentation on the NW Borneo margin has been interpreted as the product of one relatively large deltaic system, the Champion Delta. However, several lines of evidence indicate that the Champion system was not a simple, large delta; its drainage basin was too small, fluvial outcrops indicate multiple, relatively small rivers and outcrop studies indicate the same facies associations as the diverse, modern depositional systems. The number and location of rivers reaching the shoreline changed as rapidly subsiding footwall synclines, episodically active inversion anticlines and growth faults created an evolving structurally-generated topography that not only controlled drainage pathways, but also segregated Champion strata into thick, wave-dominant and tide-dominant successions. Although the principal rivers within the Champion system, the Limbang, Padas and Trusan Rivers, transport significant loads of coarse sediment, the intermittent proximal ponding of sand in local basins, as is currently occurring in Brunei Bay, resulted in a variable delivery of sand to the shelf edge. The number and distribution of shelf edge canyons also changed with time. Consequently, the spatial and temporal distribution of deepwater sand accumulations sourced from the Champion system are not solely related to relative sea level fluctuations; such accumulations should be smaller and more scattered than those sourced from a large shelf edge delta. Because the catchments of the Champion system's principal rivers represent different provenances, the system's deepwater sands may carry the signal of specific rivers. For example, mineralogical contrasts between in the main reservoir sands of the deepwater Gumusut and Kikeh fields suggest that the relative contributions of the principal rivers shifted with time with the Trusan and Limbang Rivers dominating sand supply for the youngest reservoirs at Gumusut.
Pinta, one of the northern islands in the Galapagos archipelago, is the top of a shield volcano w... more Pinta, one of the northern islands in the Galapagos archipelago, is the top of a shield volcano which became emergent ~0.7 m.y. ago. A regional north-northwest-trending fracture system influenced the locus of volcanisin. Pinta's geologic development can be divided into an older, shield stage and a younger, fissure stage. Each stage produced a similar, yet distinct, series of evolved olivine tholeiites (magnesium number = : 52). The shield series underwent some additional shallow-level fractionation in a periodically replenished chamber. Rare-earth-element data indicate that the mantle source for both of the series has residual garnet. Higher concentrations of incompatible trace elements in the fissure series imply a lower degree of partial melting. 143 Nd/ 144 Nd and ^Sr/^Sr ratios suggest that both series have an enriched, hotspot-type source. Despite close proximity to the Galapagos spreading ridge, Pinta's lavas lack features characteristic of mid-ocean ridge basalts. The isotopic and rare-earth-element data from Pinta and the other northern islands are consistent with previous models for the Galapagos spreading ridge, which require north-south axially directed transfer of enriched asthenosphere and/or melts from the Galapagos hotspot to the Galapagos Ridge.
The Mississippian Meramecian Series in the STACK (Sooner Trend Anadarko [Basin] Canadian Kingfish... more The Mississippian Meramecian Series in the STACK (Sooner Trend Anadarko [Basin] Canadian Kingfisher counties) and laterally equivalent units within the Caney Shale and Sycamore Limestone in the Arbuckle Mountains and Ardmore Basin (SCOOP: South Central Oklahoma Oil Province) consist of a succession of interbedded silty limestones, quartz-rich calcareous siltstones, argillaceous siltstones, and organic-rich mudstones that form conventional and unconventional reservoirs. Core, well-log, and outcrop data are integrated to develop a regional stratigraphic framework from the STACK to SCOOP, characterize the depositional environments, and map the distribution of organic-rich facies within the Meramecian Series. In the STACK , the Meramec was divided into 7 shallowing-upward sequence-stratigraphic cycles or zones. The cycles are capped by shales interpreted as marine-flooding surfaces. In the STACK area, the Meramec sediments were deposited on a gentle ramp and are interpreted to record of...
A key consideration in tectonic models for SE Asia and opening of the South China Sea is the role... more A key consideration in tectonic models for SE Asia and opening of the South China Sea is the role that the West Baram and Tinjar Lines of NW Borneo may have played in accommodating the motion of crustal blocks displaced from Asia following India's collision. There are few studies that focus on these "lines". Using onshore geological studies and offshore seismic data to address the origin and tectonic significance of these, this paper concludes that rather than a major transform boundary between Luconia and the Dangerous Grounds, the West Baram Line marks the boundary between domains of continental crust that underwent differential extension in the Eocene. The Baram Basin is underlain by hyperextended continental crust on the NE side of the Baram Line. The strong contrast in the geological features across the Tinjar and West Baram Lines likely reflects ancient differences in crustal rheology with Luconia being the more rigid block. Although lack of significant strike slip faulting along the West Baram Line poses problems for tectonic models in which a wide proto-South China Sea is subducted beneath NW Borneo, intra-plate deformation, such as partial inversion of the Dangerous Grounds rift, offers a potential mechanism to mass balance blocks displaced from Asia with the reduced strike slip motion along the West Baram Line.
Tectonic models for Borneo's Cenozoic evolution differ in several aspects, particularly in the ex... more Tectonic models for Borneo's Cenozoic evolution differ in several aspects, particularly in the extent to which they include paleomagnetic data suggestive of strong counterclockwise rotation between 30 and 10 Ma. Key areas are undersampled. We present the results of a paleomagnetic study of Eocene to Early Miocene sandstones from northwest Sabah, principally from the Crocker Formation. We obtained reliable site means from 11 locations along a 250 km northeast-southwest transect using thermal demagnetization to isolate characteristic remanent magnetization (ChRM) directions. The Crocker Formation sandstones are pervasively remagnetized; pyrrhotite dominates the ChRM signal. Locations can be grouped into different domains on the basis of the relative sense of rotation about a vertical axis. Mean ChRM directions for seven locations between Kota Kinabalu and Keningau (declination, dec 12°-19°; inclination, inc-22°-23°) indicate minor clockwise rotation and modest tilting, whereas two locations near Tenom (dec 321°-345°, inc-6°-24°) record counterclockwise rotation and modest tilting. Although we cannot precisely date the age of remagnetization, the results of fold tests from 4 locations, interpreted within the regional structural framework, strongly indicate that remagnetization occurred between 35 and 15 Ma, the waning stages of the Sarawak orogeny to an early phase of the Sabah orogeny. Our results pose serious diffi culties for current tectonic models in which Borneo rotates 50° counterclockwise as a rigid block between 30 and 10 Ma. With respect to prior paleomagnetic studies, we suspect that an early episode of strong regional counterclockwise rotation (before 35 Ma) was over-printed not only by differential clockwise rotation of crustal blocks during opening of the South China Sea (32-23 Ma), but also locally by a younger (after 10 Ma) counterclockwise rotation.
The Energy Citations Database (ECD) provides access to historical and current research (1948 to t... more The Energy Citations Database (ECD) provides access to historical and current research (1948 to the present) from the Department of Energy (DOE) and predecessor agencies.
SEG Technical Program Expanded Abstracts 1993, 1993
Page 1. Northern New Guinea Hydrocarbon Potential: New Constraints from Tectonic Subsidence Analy... more Page 1. Northern New Guinea Hydrocarbon Potential: New Constraints from Tectonic Subsidence Analysis and Seismic Stratigraphy John D. Pigott, University of Oklahoma; Douglas G. Neese*, Maxus Energy Corp.; Andrew B. Cullen, Pecten International SS4.6 ...
... are rather cool and suggest a fore-arc rather than back-arc setting, although thermal disequi... more ... are rather cool and suggest a fore-arc rather than back-arc setting, although thermal disequilibrium within the rapidly deposited, thick Wewak se ... Unless future work can demonstrate oil-prone source rocks or active oil seeps, the Ramu basin can be regarded as a gas-prone ...
The Usun Apau plateau lies in a remote area of Sarawak along the Tinjar Line, which defines the o... more The Usun Apau plateau lies in a remote area of Sarawak along the Tinjar Line, which defines the onshore part of a suture between the Luconia and Dangerous Grounds blocks. Reconnaissance studies in late 1950s established that the plateau is composed of a bimodal suite of young volcanic rocks, but no further work exists to constrain the age and petrogenesis of the Usun Apau volcanics. We present and discuss new data from a suite of volcanic rocks recently collected from the Usun Apau region. These data include 40 Ar-39 Ar age dates of mineral separates, major and trace element geochemistry, and Sr, Nd, Pb isotope geochemistry. The Usun Apau plateau is constructed largely of dacite and andesite erupted between 3.9 and 4.1 Ma. Minor basaltic dikes and flows (ca. 2.1 Ma) represent a distinctly younger episode of volcanism that is similar in age and character to the Linau Balui basalts about 100 km SE of the plateau. Although the trace element and isotopic suites from both areas indicate the parental melts were generated from a garnet-bearing, LILE-enriched, non-HIMU OIB-like mantle source, depletion in the HREEs and a negative Nb anomaly impart some characteristics of an island arc-type source contribution. The Usun Apau and Linau Balui volcanics are too young to be directly linked to subduction beneath Borneo; indicating a source region possibly modified by an older episode of subduction. Sr, Nd, Pb inter-isotope correlations plot within the same arrays as Pliocene basalts from the Southern Sulu Arc (500 km NE) which suggests much of northern and central Borneo is underlain by similar lithosphere. Assimilationfractional crystallization modeling indicates that differentiation of the Usun Apau dacite magmas included assimilation of continental crust with very low 143 Nd/ 144 Nd. Modeling different basement compositions as contaminants yielded non-unique results. Triassic Malay granite and different Archean granites represent plausible types of assimilants; whereas crust of Dangerous Grounds and Kontum Plateau do not.
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