TY - JOUR A1 - John, Cedric Michael A1 - Adatte, Thierry A1 - Mutti, Maria T1 - Regional trends in clay mineral fluxes to the Queensland margin and ties to middle Miocene global cooling N2 - Three ODP sites located on the Marion Plateau, Northeast Australian margin, were investigated for clay mineral and bulk mineralogy changes through the early to middle Miocene. Kaolinite to smectite (K/S) ratios, as well as mass accumulation rates of clays, point to a marked decrease in accumulation of smectite associated with an increase in accumulation of kaolinite starting at similar to 15.6 Ma, followed by a, second increase in accumulation of kaolinite at similar to 13.2 Ma. Both of these increases are correlative to an increase in the calcite to detritus ratio. Comparison of our record with published precipitation proxies from continental Queensland indicates that increases in kaolinite did not correspond to more intense tropical-humid conditions, but instead to periods of greater aridity. Three mechanisms are explored to explain the temporal trends in clad, on the Marion Plateau: sea-level changes, changes in oceanic currents, and denudation of the Australian continent followed by reworking and eolian transport of clays. Though low mass accumulation rates of kaolinite are compatible with a possible contribution of eolian material after 14 Ma, when Australia became more arid, the lateral distribution of kaolinite along slope indicates mainly fluvial input for all clays and thus rules out this mechanism as well as oceanic current transport as the main controls behind clay accumulation on the plateau. We propose a model explaining the good correlation between long-term sea-level fall, decrease in smectite accumulation, increase in kaolinite accumulation and increase in carbonate input to the distal slope locations. We hypothesize that during low sea level and thus periods of drier continental climate in Queensland, early Miocene kaolinite-rich lacustrine deposits were being reworked, and that the progradation of the heterozoan carbonate platforms towards the basin center favored input of carbonate to the distal slope sites. The major find of our study is that increase kaolinite fluxes on the Queensland margin during the early and middle Miocene did not reflect the establishment of a tropical climate, and this stresses that care must be taken when reconstructing Australian climate based on deep-sea clay records alone. Y1 - 2006 UR - http://www.sciencedirect.com/science/journal/00310182 U6 - https://doi.org/10.1016/j.palaeo.2005.09.010 SN - 0031-0182 ER - TY - JOUR A1 - Knoerich, Andrea Claudia A1 - Mutti, Maria T1 - Missing aragonitic biota and the diagenetic evolution of heterozoan carbonates : a case study from the Oligo- Miocene of the central Mediterranean N2 - Several previous studies have addressed the diagenetic evolution of heterozoan carbonate assemblages. Generally it is assumed that early diagenetic processes in heterozoan settings are mainly destructive, including abrasion and dissolution on the sea floor. Constructive diagenesis (cementation) is delayed to later stages in the burial environment, with pressure solution of calcitic grains acting as a cement source. This paper presents a study of Oligo- Miocene inner- to outer-ramp heterozoan carbonates from the Central Mediterranean (Maltese Islands and Sicily) indicating that early diagenetic processes are more important than previously assumed. Four to five different cement types, including fibrous, two types of epitaxial, bladed and blocky cement, are distinguished based on transmitted light microscopy. Cathodoluminescence microscopy allowed a differentiation between primary high-Mg calcitic (fibrous and epitaxial cement I) and primary low-Mg calcitic (epitaxial cement II, bladed and blocky) cements. Stable-isotope data indicate cement precipitation from marine, marine-derived, and meteoric waters. Trace-element analyses point to cementation in an open system (Maltese Islands) and a closed system (Sicily). Our investigations show that the majority of constructive diagenetic processes in these rocks occurs rather early in the shallow, marine burial environment, which is transitional between the marine seafloor and the deep-burial diagenctic environment. The main cement source in this environment is assumed to be aragonite. We suggest careful consideration of the importance of aragonitic components in fossil heterozoan settings, which seem to be more abundant than previously assumed and can act as a major early cement source. Due to the low preservation potential of these components, detailed geochemical studies are necessary to detect aragonite as the cement source. Our findings also have implications when considering the reservoir qualities of these rocks, because primary porosity can be occluded early and secondary porosity is not preserved Y1 - 2006 UR - http://jsedres.geoscienceworld.org/ U6 - https://doi.org/10.2110/Jsr.2006.065 SN - 1527-1404 ER - TY - JOUR A1 - Iryu, Yasufumi A1 - Matsuda, Hiroki A1 - Machiyama, Hideaki A1 - Piller, Werner E. A1 - Quinn, Terrence M. A1 - Mutti, Maria T1 - Introductory perspective on the COREF project JF - The island arc : official journal of the Geological Society of Japan N2 - Coral reefs are tropic to subtropic, coastal ecosystems comprising very diverse organisms. Late Quaternary reef deposits are fossil archives of environmental, tectonic and eustatic variations that can be used to reconstruct the paleoclimatic and paleoceano-graphic history of the tropic surface oceans. Reefs located at the latitudinal limits of coral-reef ecosystems (i.e. those at coral-reef fronts) are particularly sensitive to environmental changes-especially those associated with glacial-interglacial changes in climate and sealevel. We propose a land and ocean scientific drilling campaign in the Ryukyu Islands (the Ryukyus) in the northwestern Pacific Ocean to investigate the dynamic response of the corals and coral-reef ecosystems in this region to Late Quaternary climate and sealevel change. Such a drilling campaign, which we call the COREF (coral-reef front) Project, will allow the following three major questions to be evaluated: (i) What are the nature, magnitude and driving mechanisms of coral-reef front migration in the Ryukyus? (ii) What is the ecosystem response of coral reefs in the Ryukyus to Quaternary climate changes? (iii) What is the role of coral reefs in the global carbon cycle? Subsidiary objectives include (i) the timing of coral-reef initiation in the Ryukyus and its causes; (ii) the position of the Kuroshio current during glacial periods and its effects on coral-reef formation; and (iii) early carbonate diagenetic responses as a function of compounded variations in climate, eustacy and depositional mineralogies (subtropic aragonitic to warm-temperate calcitic). The geographic, climatic and oceanographic settings of the Ryukyu Islands provide an ideal natural laboratory to address each of these research questions. KW - coral KW - Integrated Ocean Drilling Program KW - International Continental Scientific Drilling Program KW - limestone KW - Quaternary KW - reef KW - Ryukyu Group KW - Ryukyu Islands KW - sealevel Y1 - 2006 U6 - https://doi.org/10.1111/j.1440-1738.2006.00537.x SN - 1038-4871 VL - 15 IS - 4 SP - 393 EP - 406 PB - Wiley-Blackwell CY - Oxford ER - TY - JOUR A1 - Halfar, Jochen A1 - Godinez-Orta, Lucio A1 - Mutti, Maria A1 - Valdez-Holguin, Jose Eduardo A1 - Borges, Jose M. T1 - Carbonates calibrated against oceanographic parameters along a latitudinal transect in the Gulf of California, Mexico N2 - Trophic resources are an important control governing carbonate production. Though this importance has long been recognized, no calibration exists to quantitatively compare biogenic assemblages within trophic resource fields. This study presents a field calibration of carbonate producers in a range of settings against high-resolution in situ measurements of nutrients, temperature and salinity. With its latitudinal extent from 30 degrees to 23 degrees N, the Gulf of California, Mexico, spans the warm-temperate realm and encompasses nutrient regimes from oligo-mesotrophic in the south to eutrophic in the north. Accordingly, from south to north carbonates are characterized by: (i) coral- dominated shallow carbonate factories (5-20 m water depth) with average sea-surface temperatures of 25 degrees C (min. 18 degrees C, max. 31 degrees C), average salinities of 35.06 parts per thousand and average chlorophyll a levels, which are a proxy for nutrients, of 0.25 mg Chl a m(-3) (max. 0.48, min. 0.1). (ii) Red algal-dominated subtidal to inner- shelf carbonate formation (10-25 m) in the central Gulf of California exhibiting average temperatures of 23 degrees C (min. 18 degrees C, max. 30 degrees C), average salinities of 35.25 parts per thousand, and average Chl a levels of 0.71 Chl a m(-3) (max. 5.62, min. 0). (iii) Molluskan bryozoan-rich inner to outer shelf factories in the northern Gulf of California (20-50 m) with average sea surface temperatures of only 20 degrees C (min. 13 degrees C, max 29 degrees C), average salinities of 35.01 parts per thousand, and average contents of 2.2 mg Chl a m(-3) (max. 8.38, min. 0). By calibrating sedimentological data with in situ measured oceanographic information in different environments, the response of carbonate producers to environmental parameters was established and extrapolated to carbonates on a global scale. The results demonstrate the importance of recognizing and quantifying trophic resources as a dominant control determining the biogenic composition and facies character of both modern and fossil carbonates Y1 - 2006 UR - http://www3.interscience.wiley.com/cgi-bin/issn?DESCRIPTOR=PRINTISSN&VALUE=0037-0746 U6 - https://doi.org/10.1111/j.1365-3091.2005.00766.x SN - 0037-0746 ER -