Comparative Sedimentology of a
Mixed Carbonate/Siliciclastic System
and Pinnacle Reefs, Belize, Central
America
Background
A recurring theme of the sedimentary record is the coexistence, mixing, and succession of
carbonates and siliciclastics. Awareness of the processes and controls influencing lateral facies
variations and potential reservoir geometries in modern mixed systems can provide much needed
guidelines to the interpretation of ancient mixed systems. The purpose of this seminar is to
introduce the participant to the recent mixed carbonate and siliciclastic system in Belize, C.A. to
better understand the scale, dynamics and geometry of both carbonate and siliciclastic systems.
Objectives
Understand the processes and controls influencing the lateral distribution of facies in a modern
mixed carbonate/siliciclastic system.* To relate the distribution of recent barrier and pinnacle reefs,
incised valleys, restricted circulation lagoons and siliciclastic shorelines to probable 3-D geometries
of similar ancient systems in the subsurface. Schedule Seminar participants will observe the
lateral coexistence of a pure siliciclastic shoreline and coastal plain, mixed carbonate/siliciclastic
lagoons and carbonate reefs. The primary objective will be to evaluate lateral variations in these
environments and project what the 3-D distribution of facies may be in the subsurface.
Multi-channel and high-resolution single-channel seismic lines will be used to discuss the eustatic
and structural controls on both the present-day facies distribution, as well as the patterns of
pre-Holocene drainage that formed incised valleys. Special attention will be focused in the field on
geometries of potential reservoir facies, the distribution and types of primary porosity and the
potential for secondary porosity in response to changing sea level. Field observations will be
augmented with prepared cores through representative intervals, combined with sediment sampling
and collection of short cores. An overflight will then provide a regional perspective forthe
distribution of various facies belts visited during the trip.
Itinerary
Day 1 Travel to Belize City, C.A. Meet in early afternoon at airport for flight to Placentia.
Overnight in Placentia
Day 2 Introduction to Belize, by boat to examine coastal marine siliciclastics, coastal plain fluvial deposits, estuary organic deposition, an incised valley, coastal reefs among siliciclastics. Overnight in Placentia
Day 3 Transect by boat across Belize lagoon to examine lateral facies relationships of carbonate
and siliciclastic facies as well as the distribution and build-up geometries of pinnacle reefs, patch
reefs, and rhomboid shoals (atolls). Overnight on barrier reef at South Water Cay
Day 4 Geometry and associated facies of the barrier reef and platform margin morphology. Return
across lagoon to overnight in Dangriga
Day 5 AM overflight of lagoon and barrier from Placentia to Ambergris Cay.PM by boat to
examine barrier/fringing reefs and marine cementation. Overnight San Pedro, Ambergris Cay
Day 6 Northern lagoon to reef transect. Examine shallow-water lagoon facies, tidal flats and
dolomite crusts, intra-lagoon sand shoal, mudbanks, shelf sands and reefs. Overnight San Pedro
Day 7 AM Fly Ambergris Cay to Belize City to meet connecting flights Field Trip
Leaders
Dr. D. McNeill , Associate Scientist in Marine Geology & Geophysics, carbonate
sedimentology, stratigraphy
Dr. G. Eberli , Associate Prof. of Marine Geology & Geophysics, seismic stratigraphy,
petrophysics
Dr. Peter K. Swart , Prof. of Marine Geology & Geophysics, carbonate diagenesis, dolomitization,
stable-isotope geochemistry
Turnkey fee of $2,700/participant includes all meals and accommodations starting from arrival in,
and return to, Belize City. Includes land and water transportation in Belize, overflight, guidebook
and slide set.
Further Information
Ms. Karen Fleites, phone 305 361-4684, fax 305 361-4632,email:kfleites@rsmas.miami.edu
Dr. Don McNeill, phone 305 361-4790, fax 305 361-4632,email: dmcneill@rsmas.miami.edu
Dr. Gregor Eberli phone 305 361-4678, fax 3-5 361-4632, email:geberli@rsmas.miami.edu
Dr. Peter K. Swart phone 305 361-4103, fax 3-5 361-4632, email:pswart@rsmas.miami.edu