Products of chlorophyll diagenesis from DSDP Leg 57 Holes

Tetrapyrrole pigments isolated from sediments retrieved during Leg 57 include pheophytin-a, a myriad of chlorins, free-base deoxophylloerythroetioporphyrin (DPEP), as well as copper and nickel porphyrins. Their richness, both qualitatively and quantitatively, in chlorin tetrapyrroles affords a relatively complete study on the early diagenesis of chlorophyll. Our studies, coupled with those in the preceding chapter by Louda et al., point out the influence of pre- and postdepositional environments upon the mode of chlorophyll diagenesis. Formation of tetrapyrroles, collectively called "petroporphyrins," is seen to occur in only a limited set of environmental conditions (see Baker and Palmer, 1978). The more generalized route of chlorophyll diagenesis, at least in the ocean, results in removal of tetrapyrrole pigment, from the fossil record. Late diagenetic products, metalloporphyrins, are found to represent an extremely minor component of the tetrapyrrole assemblage in sediments studied from the Japan Trench. The products of chlorophyll diagenesis isolated from Japan Trench sediments allow expansion of previous diagenetic schemes (Baker and Palmer, 1978; Triebs, 1936) and indicate directions for future studies.

Mineralogy and geochemistry of alteration products in DSDP Leg 81 Holes

Alteration products of basalts from the four holes drilled during Leg 81 were studied and found to be characterized by the widespread occurrence of trioctahedral clay minerals (Mg smectite to chlorite). In some cases zeolites (analcite, chabazite) are associated with the saponite. A more oxidizing stage is marked by a saponite-celadonite association, presenting the geochemical characteristics of hydrothermal processes. Later stages of alteration are represented by palagonitization and subaerial weathering at two sites. These different alteration processes of basalts from Leg 81 record the paleoenvironment during the first opening stages of the Northeast Atlantic Ocean in the Paleocene-Eocene periods.

Seagrass time-series analysis products, in Moreton Bay, Australia, with links to GeoTIFFs

The spatial and temporal dynamics of seagrasses have been well studied at the leaf to patch scales, however, the link to large spatial extent landscape and population dynamics is still unresolved in seagrass ecology. Traditional remote sensing approaches have lacked the temporal resolution and consistency to appropriately address this issue. This study uses two high temporal resolution time-series of thematic seagrass cover maps to examine the spatial and temporal dynamics of seagrass at both an inter- and intra-annual time scales, one of the first globally to do so at this scale. Previous work by the authors developed an object-based approach to map seagrass cover level distribution from a long term archive of Landsat TM and ETM+ images on the Eastern Banks (~200 km**2), Moreton Bay, Australia. In this work a range of trend and time-series analysis methods are demonstrated for a time-series of 23 annual maps from 1988 to 2010 and a time-series of 16 monthly maps during 2008-2010. Significant new insight was presented regarding the inter- and intra-annual dynamics of seagrass persistence over time, seagrass cover level variability, seagrass cover level trajectory, and change in area of seagrass and cover levels over time. Overall we found that there was no significant decline in total seagrass area on the Eastern Banks, but there was a significant decline in seagrass cover level condition. A case study of two smaller communities within the Eastern Banks that experienced a decline in both overall seagrass area and condition are examined in detail, highlighting possible differences in environmental and process drivers. We demonstrate how trend and time-series analysis enabled seagrass distribution to be appropriately assessed in context of its spatial and temporal history and provides the ability to not only quantify change, but also describe the type of change. We also demonstrate the potential use of time-series analysis products to investigate seagrass growth and decline as well as the processes that drive it. This study demonstrates clear benefits over traditional seagrass mapping and monitoring approaches, and provides a proof of concept for the use of trend and time-series analysis of remotely sensed seagrass products to benefit current endeavours in seagrass ecology.