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Late Pliocene to Holocene platform evolution in northern Belize, and comparison with coeval deposits in southern Belize and the Bahamas
Mazzullo, S. J.
Mazzullo, S. J.
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Authors
Mazzullo, S. J.
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Location
Time Period
Advisors
Original Date
Digitization Date
Issue Date
2006-10
Type
Article
Genre
Keywords
Belize,Dolomitization,Platform evolution,Pliocene to Holocene,Rimmed platform,Tectonics
Subjects (LCSH)
Citation
Mazzullo, S.J. 2006. Late Pliocene to Holocene platform evolution in northern Belize, and comparison with coeval deposits in southern Belize and the Bahamas. Sedimentology.
Abstract
Lithostratigraphy, depositional facies architecture, and diagenesis of upper
Pliocene to Holocene carbonates in northern Belize are evaluated based on a
ca 290 m, continuous section of samples from a well drilled on Ambergris
Caye that can be linked directly to outcrops of Pleistocene limestone, and of
overlying Holocene sediments. Upper Pliocene outer-ramp deposits are
overlain unconformably by Pleistocene and Holocene reef-rimmed platforms
devoid of lowstand siliciclastics. Tectonism controlled the location of the
oldest Pleistocene platform margin and coralgal barrier reef, and periodically
affected deposition in the Holocene. A shallow, flat-topped, mostly
aggradational platform was maintained in the Holocene by alternating
periods of highstand barrier-reef growth and lowstand karstification,
differential subsidence, and the low magnitude of accommodation space
increases during highstands. Facies in Pleistocene rocks to the lee of the
barrier reef include: (i) outer-shelf coralgal sands with scattered coral patch
reefs; (ii) a shoal–water transition zone comprising nearshore skeletal and
oolitic sands amidst scattered islands and tidal flats; and (iii) micritic innershelf
deposits. Four glacio-eustatically forced sequences are recognized in the
Pleistocene section, and component subtidal cycles probably include forced
cycles and autocycles. Excluding oolites, Holocene facies are similar to those
in the Pleistocene and include mud-mounds, foraminiferal sand shoals in the
inner shelf, and within the interiors of Ambergris and surrounding cayes,
mangrove swamps, shallow lagoons, and tidal and sea-marginal flats. Meteoric
diagenesis of Pliocene and Pleistocene rocks is indicated by variable degrees of
mineralogic stabilization, generally depleted whole-rock d18O and d13C values,
and meniscus and whisker-crystal cements. Differences in the mineralogy and
geochemistry of the Pliocene and Pleistocene rocks are attributed to variable
extent of meteoric alteration. Dolomitization in the Pliocene carbonates may
have begun syndepositionally and continued into the marine shallow-burial
environment. Positive dolomite d18O and d13C values suggest precipitation
from circulating, near-normal marine fluids that probably were modified
somewhat by methanogenesis. Sedimentologic and diagenetic attributes of the
Pliocene–Pleistocene rocks in the study area are similar to those in the
Bahamas with which they share a common history of sea-level fluctuations and
climate change.
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Description
The full text is not available on SOAR. Access this article via the commercial databases licensed by University Libraries: http://libcat.wichita.edu/vwebv/holdingsInfo?searchId=817&recCount=30&recPointer=1&bibId=1334578
Publisher
International Association of Sedimentologists
Journal
Book Title
Series
Sedimentology;v.53 no.5
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PubMed ID
DOI
ISSN
1365-3091