Geology of Isla de Mona, Puerto Rico

González, Luis A.; Ruiz, H.; Taggart, Bruce E.; Budd, Ann F.; Monell, Vanessa

doi:10.1016/s0070-4571(04)80031-1

Cited by 9 publications

(3 citation statements)

References 14 publications

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“…Marine coastal endolithic communities were sampled from Isla de Mona (18.0867° N, 67.8894° W), a small, predominantly carbonate (Mona Dolomite and Lirio Limestone) island located 40 miles West of Puerto Rico 24 . Samples were obtained from six separate localities along the shore, collected within the bioerosional notch of the intertidal zone.…”

Section: Methodsmentioning

confidence: 99%

Carbon fixation from mineral carbonates

2017

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Photoautotrophs assimilate oxidized carbon obtained from one of two sources: dissolved or atmospheric. Despite its size, the pool of lithospheric carbonate is not known to be a direct source for autotrophy. Yet, the mechanism that euendolithic cyanobacteria use to excavate solid carbonates suggests that minerals could directly supply CO2 for autotrophy. Here, we use stable isotopes and NanoSIMS to show that the cyanobacterium Mastigocoleus testarum derives most of its carbon from the mineral it excavates, growing preferentially as an endolith when lacking dissolved CO2. Furthermore, natural endolithic communities from intertidal marine carbonate outcrops present carbon isotopic signatures consistent with mineral-sourced autotrophy. These data demonstrate a direct geomicrobial link between mineral carbonate pools and reduced organic carbon, which, given the geographical extent of carbonate outcrops, is likely of global relevance. The ancient fossil record of euendolithic cyanobacteria suggests that biological fixation of solid carbonate could have been relevant since the mid-Proterozoic.

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Section: Methodsmentioning

confidence: 99%

Carbon fixation from mineral carbonates

2017

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“… δ 18 O versus δ 13 C cross‐plot of Neogene dolomites including those attributed to a mixingzone (Ward & Halley, 1985; Humphrey, 1988, 2000; Kimbell, 1993; Fouke, 1994; Lucia & Major, 1994; González et al ., 1997; Gaswirth et al ., 2007; Budd & Mathias, 2015; Sumrall et al ., 2015, 2016) and marine dolomites of the Bahamas (Higgins et al ., 2018, and referances therein). Two main trends are visible and define mixing lines to the marine end member.…”

Section: Detecting Biogeochemical Signatures Of Mixing‐zone Dolomitesmentioning

confidence: 99%

“…Some proposed examples of Cenozoic mixing‐zone dolomites from around the Gulf of Mexico and the Caribbean provide further details of potential textures, luminescence, isotopic and trace element signatures of mixing‐zone dolomites. These examples include the Eocene–Oligocene of the Central Florida Platform, the Mio‐Pleistocene of Bonaire and Curaçao, Holocene of north‐eastern Yucatan Platform, Isla de Monas in Puerto Rico, South Andros Island in the Bahamas and Ambergris Cay in Belize (Ward & Halley, 1985; Mazzullo et al ., 1987; Cander, 1994; Fouke et al ., 1996; González et al ., 1997; Whitaker & Smart, 1998; Teal et al ., 2000; Gaswirth et al ., 2007; Sumrall et al ., 2015). Finally, from the comparative analysis of the textural, chemical and isotopic variabilities of the dolomite locales re‐evaluated here, this work emphasizes the need for systematic facies‐scale to crystal‐scale studies of the geochemical and potentially isotopic composition of possible ancient mixing zones.…”

Section: Introductionmentioning

confidence: 99%

Biogeochemical reappraisal of the freshwater–seawater mixing‐zone diagenetic model

et al. 2021

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First proposed nearly half a century ago, the mixing-zone model of dolomitization enjoyed a brief stay in the limelight before falling out of favour. Despite extended past criticism, arguments that build on its current validity are presented and discussed. The coastal mixing zone can be seen as an aquifer system exhibiting marked physicochemical gradients, reflective of the admixture of low salinity freshwater and seawater sources with variable redox potentials. This perspective requires a more holistic look at the mixing zone, not only as a gradient of major element concentrations, but also as the locus of enhanced subsurface redox sensitive reactions that occur at the pore-space scale within a moveable diagenetic front. Combined genomic and isotopic data indicate that an active subsurface biosphere thrives in the mixing zone. This could facilitate Mg 2+ dehydration, generate alkalinity, consume protons and mobilize potentially catalyzing ions (i.e. Mn and Zn), which are all low temperature factors thought to promote dolomite formation from soluble precursors. In the updated model, the advective mix of fluids with contrasting composition modulate a range of biogeochemically induced mineral dissolution and reprecipitation reactions. Biotic and abiotic interactions between these fluids affect carbonate equilibrium and result in dissolution of soluble aragonitic and calcitic phases, while dolomite precipitates (as cement) and neomorphic replacement. The secondary dolomite often exhibits compositional heterogeneity and contentious δ 18 O signatures indicative of re-equilibration. The role of manganese, zinc, intermediate sulphur species and ammonia are far from being fully understood, nor is their fingerprint in ancient deposits. Application of in situ spectroscopic imaging techniques, clumped and metal isotope analyses, as well as a more extended use of traditional approaches, such as sulphur isotopes, are poised to open many opportunities to further explore the biogeochemistry of this diagenetic environment and how it relates to platform dolomitization.

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Coastal Caves and Karst of the Puerto Rican Islands

Lace¹

2013

Coastal Karst Landforms

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Geology of Isla de Mona, Puerto Rico

Cited by 9 publications

References 14 publications

Carbon fixation from mineral carbonates

Carbon fixation from mineral carbonates

Biogeochemical reappraisal of the freshwater–seawater mixing‐zone diagenetic model

Coastal Caves and Karst of the Puerto Rican Islands

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