Tropical view of Quaternary sequence stratigraphy: Siliciclastic accumulation on slopes east of the Great Barrier Reef since the Last Glacial Maximum

Geology ◽  
2003 ◽  
Vol 31 (11) ◽  
pp. 1013 ◽  
Author(s):  
Michael C. Page ◽  
Gerald R. Dickens ◽  
Gavin B. Dunbar
Keyword(s):  
Great Barrier Reef ◽  
Sequence Stratigraphy ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Barrier Reef ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

scholarly journals Reef-flat and back-reef development in the Great Barrier Reef caused by rapid sea-level fall during the Last Glacial Maximum (30–17 ka)

Geology ◽  
2019 ◽  
Vol 48 (1) ◽  
pp. 39-43 ◽  
Author(s):  
Kazuhiko Fujita ◽  
Noriko Yagioka ◽  
Choko Nakada ◽  
Hironobu Kan ◽  
Yosuke Miyairi ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Sea Level ◽  
Last Glacial Maximum ◽  
Reef Flat ◽  
Barrier Reef ◽  
Back Reef ◽  
Last Glacial ◽  
Reef Environments ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract Reef growth patterns and the development of associated environments have been extensively studied from reef deposits from Holocene and previous interglacial highstands. However, reefs that grew during glacial lowstands are comparatively poorly understood. Here we show the formation of reef-flat and back-reef environments following rapid sea-level fall (15–20 mm yr−1 and 20–40 m in magnitude) during the Last Glacial Maximum (LGM) on the present shelf edge of the Great Barrier Reef. Sedimentological and foraminiferal analyses of unconsolidated reef sediments recovered in cores 111–140 m below sea level at Hydrographers Passage during Integrated Ocean Drilling Project (IODP) Expedition 325 reveal the occurrence of a benthic foraminiferal assemblage dominated by the genera Calcarina and Baculogypsina, which is common in modern reef-flat and back-reef environments in the Great Barrier Reef and elsewhere. This assemblage is associated with higher foraminiferal proportions in reef sediments and higher proportions of well-preserved Baculogypsina tests in the same intervals, which also characterize reef-flat environments. Radiocarbon (14C–accelerator mass spectrometry) ages of reef-flat dwelling foraminifers (n = 22), which indicate the time when these foraminifers were alive, are consistent with the timing of the two-step sea-level fall into the LGM as defined by the previously published well-dated coralgal record. This foraminiferal evidence suggests the development of geomorphically mature fringing reefs with shallow back-reef lagoons during the LGM. Our results also imply that back-reef sediment accumulation rates during the LGM lowstand were comparable to those during the Holocene highstand.

Reconstructions of the past distribution of Testudo graeca mitochondrial lineages in the Middle East and Transcaucasia support multiple refugia since the Last Glacial Maximum

2021 ◽  
pp. 10-17
Author(s):  
Oguz Turkozan
Keyword(s):  
Middle East ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Testudo Graeca ◽  
Last Glacial ◽  
The Past ◽  
Precipitation Seasonality ◽  
Multiple Refugia ◽  
The Last Glacial Maximum ◽  
The Last Glacial

A cycle of glacial and interglacial periods in the Quaternary caused species’ ranges to expand and contract in response to climatic and environmental changes. During interglacial periods, many species expanded their distribution ranges from refugia into higher elevations and latitudes. In the present work, we projected the responses of the five lineages of Testudo graeca in the Middle East and Transcaucasia as the climate shifted from the Last Glacial Maximum (LGM, Mid – Holocene), to the present. Under the past LGM and Mid-Holocene bioclimatic conditions, models predicted relatively more suitable habitats for some of the lineages. The most significant bioclimatic variables in predicting the present and past potential distribution of clades are the precipitation of the warmest quarter for T. g. armeniaca (95.8 %), precipitation seasonality for T. g. buxtoni (85.0 %), minimum temperature of the coldest month for T. g. ibera (75.4 %), precipitation of the coldest quarter for T. g. terrestris (34.1 %), and the mean temperature of the driest quarter for T. g. zarudyni (88.8 %). Since the LGM, we hypothesise that the ranges of lineages have either expanded (T. g. ibera), contracted (T. g. zarudnyi) or remained stable (T. g. terrestris), and for other two taxa (T. g. armeniaca and T. g. buxtoni) the pattern remains unclear. Our analysis predicts multiple refugia for Testudo during the LGM and supports previous hypotheses about high lineage richness in Anatolia resulting from secondary contact.

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