TY  - JOUR
A1  - Tomas, Sara
A1  - Homann, Martin
A1  - Mutti, Maria
A1  - Amour, Frederic
A1  - Christ, Nicolas
A1  - Immenhauser, Adrian
A1  - Agar, Susan M.
A1  - Kabiri, Lahcen
T1  - Alternation of microbial mounds and ooid shoals (Middle Jurasssic, Morocco) - response to paleoenvironmental changes
JF  - Sedimentary geology : international journal of applied and regional sedimentology
N2  - The occurrence of neritic microbial carbonates is often related to ecological refuges, where grazers and other competitors are reduced by environmental conditions, or to post-extinction events (e.g. in the Late Devonian, Early Triassic). Here, we present evidence for Middle Jurassic (Bajocian) microbial mounds formed in the normal marine, shallow neritic setting of an inner, ramp system from the High Atlas of Morocco. The microbial mounds are embedded in cross-bedded oolitic facies. Individual mounds show low relief domal geometries (up to 3 m high and 4.5 m across), but occasionally a second generation of mounds exhibits tabular geometries (<1 m high). The domes are circular in plan view and have intact tops, lacking evidence of current influence on mound preferred growth direction or distribution patterns, or truncation. The mound fades consists almost entirely of non-laminated, micritic thrombolites with branching morphologies and fine-grained, clotted and peloidal fabrics. Normal marine biota are present but infrequent. Several lines of evidence document that microbial mound growth alternates with time intervals of active ooid shoal deposition. This notion is of general significance when compared with modern Bahamian microbialites that co-exist with active sub-aquatic dunes. Furthermore, the lack of detailed studies of Middle Jurassic, normal marine shallow neritic microbial mounds adds a strong motivation for the present study. Specifically, Bajocian mounds formed on a firmground substratum during transgressive phases under condensed sedimentation. Furthermore, a transient increase in nutrient supply in the prevailing mesotrophic setting, as suggested by the heterotrophic-dominated biota, may have controlled microbial mound stages.
KW  - Microbial mounds
KW  - Thrombolites
KW  - Ooid shoals
KW  - Paleoenvironment
KW  - Jurassic
Y1  - 2013
U6  - https://doi.org/10.1016/j.sedgeo.2013.05.008
SN  - 0037-0738
VL  - 294
SP  - 68
EP  - 82
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Amour, Frederic
A1  - Mutti, Maria
A1  - Christ, Nicolas
A1  - Immenhauser, Adrian
A1  - Benson, Gregory S.
A1  - Agar, Susan M.
A1  - Tomas, Sara
A1  - Kabiri, Lahcen
T1  - Outcrop analog for an oolitic carbonate ramp reservoir a scale-dependent geologic modeling approach based on stratigraphic hierarchy
JF  - AAPG bulletin
N2  - Considerable effort has been devoted to the development of simulation algorithms for facies modeling, whereas a discussion of how to combine those techniques has not existed. The integration of multiple geologic data into a three-dimensional model, which requires the combination of simulation techniques, is yet a current challenge for reservoir modeling. This article presents a thought process that guides the acquisition and modeling of geologic data at various scales. Our work is based on outcrop data collected from a Jurassic carbonate ramp located in the High Atlas mountain range of Morocco. The study window is 1 km (0.6 mi) wide and 100 m (328.1 ft) thick. We describe and model the spatial and hierarchical arrangement of carbonate bodies spanning from largest to smallest: (1) stacking pattern of high-frequency depositional sequences, (2) facies association, and (3) lithofacies. Five sequence boundaries were modeled using differential global position system mapping and light detection and ranging data. The surface-based model shows a low-angle profile with modest paleotopographic relief at the inner-to-middle ramp transition. Facies associations were populated using truncated Gaussian simulation to preserve ordered trends between the inner, middle, and outer ramps. At the lithofacies scale, field observations and statistical analysis show a mosaiclike distribution that was simulated using a fully stochastic approach with sequential indicator simulation.
 This study observes that the use of one single simulation technique is unlikely to correctly model the natural patterns and variability of carbonate rocks. The selection and implementation of different techniques customized for each level of the stratigraphic hierarchy will provide the essential computing flexibility to model carbonate settings. This study demonstrates that a scale-dependent modeling approach should be a common procedure when building subsurface and outcrop models.
Y1  - 2013
U6  - https://doi.org/10.1306/10231212039
SN  - 0149-1423
VL  - 97
IS  - 5
SP  - 845
EP  - 871
PB  - American Association of Petroleum Geologists
CY  - Tulsa
ER  -