F. S. P. van Buchem

Bio: F. S. P. van Buchem is an academic researcher from Maersk Oil. The author has contributed to research in topics: Facies & Sedimentary depositional environment. The author has an hindex of 12, co-authored 19 publications receiving 807 citations. Previous affiliations of F. S. P. van Buchem include Institut Français.

Regional stratigraphic architecture and reservoir types of the Oligo-Miocene deposits in the Dezful Embayment (Asmari and Pabdeh Formations) SW Iran

Abstract: Abstract A regional sequence stratigraphic model is proposed for the Oligo-Miocene Asmari and Pabdeh Formations in the Dezful Embayment of SW Iran. The model is based on both new detailed sedimentological observations in outcrops, core and well logs, and an improved high-resolution chronostratigraphic framework constrained by Sr isotope stratigraphy and biostratigraphy. A better understanding of the stratigraphic architecture distinguishes four, geographically separated types of Asmari reservoirs. Three Oligocene sequences (of Rupelian, early Chattian and late Chattian age) and three Miocene sequences (of early Aquitanian, late Aquitanian and early Burdigalian age) have been distinguished, representing a period of 15.4 Ma. The stratigraphic architecture of these sequences is primarily controlled by glacio-eustatic sea-level fluctuations, which determined the distribution of carbonates, sandstones and anhydrites in this sedimentary system. Tectonic control became important in the Burdigalian with a regional tilt down towards the NE. The lithological heterogeneity, the complex geometries, and both early and late diagenetic alterations are the basis for a classification of four main stratigraphic reference types for the Asmari Reservoirs: Type 1, sandstone dominated; Type 2, mixed carbonate-siliciclastic; Type 3, mixed carbonate-anhydrite; and Type 4, carbonate dominated. The sequence stratigraphic model predicts how and when these types change laterally from one to another.

Late Aptian to Turonian stratigraphy of the eastern Arabian Plate – depositional sequences and lithostratigraphic nomenclature

Abstract: This stratigraphic article summarizes a number of observations on the mid-Cretaceous stratigraphy of Arabia made during the 2nd Arabian Plate Geology Workshop held in Abu Dhabi in January 2010. These observations pertain to the lithostratigraphic nomenclature applied on the eastern Arabian Plate and its relationship to mid-Cretaceous (Late Aptian–Turonian) depositional systems and sequences recognized plate-wide. It appears that several of the commonly applied lithostratigraphic terms are diachronous as a result of (i) plate-wide migration of carbonate and siliciclastic facies belts; (ii) the occurrence of intra-shelf basins at different times and locations; (iii) differential preservation beneath erosional unconformities; and (iv) simple differences in usage across political boundaries. A plate-wide sequence stratigraphic scheme is thus a powerful tool for regional correlation and mapping, and for reconciling lithostratigraphic differences. The studied interval can be subdivided into two primary sedimentary systems that differ in lithology, depositional geometries and dominant faunal assemblages. First, latest Aptian- and Albian-aged systems, which are characterized by volumetrically significant Arabian Shield-derived siliciclastics (both sandstones and claystones) that alternate with carbonate beds. The carbonate beds thicken up-section and have generally very low-angle, muddy ramp depositional geometries. Organic-rich basinal facies are found only in the Kazhdumi Basin in SW Iran at this time. The faunal composition of the carbonates is dominated by benthic foraminifera (notably orbitolinids). Within this succession three third-order depositional sequences are distinguished (MFS K90, K100 and K110). Secondly, Cenomanian–early Turonian-aged sedimentary systems are characterized by a marked reduction in siliciclastic influx, the development of carbonate platform to intra-shelf basin topography and deposition of basinal source rocks. Rudists are the dominant component of grainy, high-energy platform margin/barrier facies, and are also present in the platform top sediments. Within this succession three Cenomanian sequences can be correlated clearly at the scale of the plate (MFS K120, K130 and K140), whereas the number of sequences in the Turonian interval is less well known owing to significant local erosion and/or non-deposition during a period of tectonic instability. Applying this robust sequence stratigraphic framework in combination with a synthesis of biostratigraphic age calibration demonstrates the diachronous character of the Mauddud, Safaniya, Ahmadi and Mishrif formations and equivalents from the southern to the northern part of the Arabian Plate.

Sequence stratigraphy of Cenomanian–Turonian carbonate platform margins (Sarvak Formation) in the High Zagros, SW Iran: an outcrop reference model for the Arabian Plate

Abstract: Abstract A high resolution sequence stratigraphic model has been constructed for the mid-Cretaceous Sarvak Formation (in the High Zagros region of SW Iran) which was deposited close to the eastern margin of the Arabian Plate. The exceptional outcrop quality, displaying the detailed facies patterns in the transition zone from carbonate platform to intra-shelf basin, offers the rare opportunity to distinguish between the relative control of carbonate sediment supply (S) and accommodation (A) on the depositional geometries of third- and fourth-order depositional sequences. Four third-order sequences have been distinguished in the Sarvak Formation, with a duration varying between 1.5 and 3 Ma, and a thickness of 50–150 m. These are in turn composed of fourth- and fifth-order sequences that form the stratigraphic building blocks of this carbonate system. A significant distinction has been made in the third-order sequences between the early transgression (e-TST) when the system was still flat, and corresponds to a ramp setting, and the late transgression (l-TST) when the carbonate platform to intra-shelf basin topography was created. The rate of accommodation creation is identified as the dominant factor controlling the morphology of the depositional profile, and, as such, the driving motor behind the dynamics of this type of carbonate system. The dip angle of the depositional profile has a major influence on: (1) the hydrodynamics of the system; (2) the type of carbonate sediment; and (3) the volume of carbonate sediment produced. A good correlation with the third-order sequences of the Natih Formation in Oman is demonstrated, which supports a dominant control by eustatic sea-level changes and a similar response of the carbonate system to changes in the rate of sea-level rise on the southern part of the Arabian Plate. This outcrop analogue can be considered as a good reference model for the Cenomanian–Turonian carbonate platform margins of the Arabian Plate, but also as a textbook example of the response of carbonate systems to sea-level fluctuations (relative influence of accommodation and sediment supply).

The Asmari Formation Revisited: Changed Stratigraphic Allocation and New Biozonation

Abstract: The essential biostratigraphy of the Asmari Formation was outlined in the early 1950’s and thereby the only published record of the biostratigraphy before the Asmari Formation was formally described in the mid 1960’s. The traditional Iranian biostratigraphy is based on unpublished reports. Unfortunately, these reports were written in a period when the Aquitanian stage was under debate. Recent studies have shown that sediments ascribed to the Miocene “Aquitanian” are in fact Late Oligocene, Chattian in age. This was proved by the application of Sr-isotope stratigraphy to cored sections from 10 Iranian oil fields and 14 outcrop sections, within the framework of a high resolution sequence stratigraphic study down to fourth order cycles (van Buchem et al., in press). For each section, the strontium dates were plotted against the fossil ranges. The strontium ages necessitate a revision of the interpretation of the Chattian-Aquitanian boundary. The Chattian/Aquitanian boundary is marked by a major faunal turnover, with the general extinction of Archaias species and Miogypsinoides complanatus. The previous age interpretation of the early, unpublished zonations necessitates a revision, and the establishment of an updated biozonation. This new zonation and the stratigraphic ranges of selected key-species are presented here.

Sequence stratigraphy: methodology and nomenclature

Abstract: The recurrence of the same types of sequence stratigraphic surface through geologic time defines cycles of change in accommodation or sediment supply, which correspond to sequences in the rock record. These cycles may be symmetrical or asymmetrical, and may or may not include all types of systems tracts that may be expected within a fully developed sequence. Depending on the scale of observation, sequences and their bounding surfaces may be ascribed to different hierarchical orders. Stratal stacking patterns combine to define trends in geometric character that include upstepping, forestepping, backstepping and downstepping, expressing three types of shoreline shift: forced regression (forestepping and downstepping at the shoreline), normal regression (forestepping and upstepping at the shoreline) and transgression (backstepping at the shoreline). Stacking patterns that are independent of shoreline trajectories may also be defined on the basis of changes in depositional style that can be correlated regionally. All stratal stacking patterns reflect the interplay of the same two fundamental variables, namely accommodation (the space available for potential sediment accumulation) and sediment supply. Deposits defined by specific stratal stacking patterns form the basic constituents of any sequence stratigraphic unit, from sequence to systems tract and parasequence. Changes in stratal stacking patterns define the position and timing of key sequence stratigraphic surfaces. Precisely which surfaces are selected as sequence boundaries varies as a function of which surfaces are best expressed within the context of the depositional setting and the preservation of facies relationships and stratal stacking patterns in that succession. The high degree of variability in the expression of sequence stratigraphic units and bounding surfaces in the rock record means ideally that the methodology used to analyze their depositional setting should be flexible from one sequence stratigraphic approach to another. Construction of this framework ensures the success of the method in terms of its objectives to provide a process-based understanding of the stratigraphic architecture. The purpose of this paper is to emphasize a standard but flexible methodology that remains objective.