Predicting the effects of hydrologic restoration on manatees along the southwest coast of Florida

Fact Sheet ◽  
2004 ◽  
Author(s):  
Brad Stith ◽  
Jim Reid ◽  
Susan M. Butler ◽  
Terry Doyle ◽  
Cathy Langtimm
Keyword(s):  
Southwest Coast ◽  
Hydrologic Restoration

40Ar–39Ar dating of alkali basaltic dykes along the southwest coast of Greenland: Cretaceous and Tertiary igneous activity along the eastern margin of the Labrador Sea

1999 ◽  
pp. 19-29 ◽  
Author(s):  
Lotte Melchior Larsen ◽  
David C. Rex ◽  
W. Stuart Watt ◽  
Philip G. Guise
Keyword(s):  
Alkali Basalt ◽  
Dyke Swarm ◽  
Labrador Sea ◽  
Precambrian Basement ◽  
Stress Regime ◽  
Southwest Coast ◽  
Eastern Margin ◽  
Step Heating ◽  
Igneous Activity ◽  
Break Up

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Melchior Larsen, L., Rex, D. C., Watt, W. S., & Guise, P. G. (1999). 40Ar–39Ar dating of alkali basaltic dykes along the southwest coast of Greenland: Cretaceous and Tertiary igneous activity along the eastern margin of the Labrador Sea. Geology of Greenland Survey Bulletin, 184, 19-29. https://doi.org/10.34194/ggub.v184.5227 _______________ A 380 km long coast-parallel alkali basalt dyke swarm cutting the Precambrian basement in south-western Greenland has generally been regarded as one of the earliest manifestations of rifting during continental stretching prior to break-up in the Labrador Sea. Therefore, the age of this swarm has been used in models for the evolution of the Labrador Sea, although it has been uncertain due to earlier discrepant K–Ar dates. Two dykes from this swarm situated 200 km apart have now been dated by the 40Ar–39Ar step-heating method. Separated biotites yield plateau ages of 133.3 ± 0.7 Ma and 138.6 ± 0.7 Ma, respectively. One of the dykes has excess argon. Plagioclase separates confirm the biotite ages but yield less precise results. The age 133– 138 Ma is earliest Cretaceous, Berriasian to Valanginian, and the dyke swarm is near-coeval with the oldest igneous rocks (the Alexis Formation) on the Labrador shelf. A small swarm of alkali basalt dykes in the Sukkertoppen (Maniitsoq) region of southern West Greenland was also dated. Two separated kaersutites from one sample yield an average plateau age of 55.2 ± 1.2 Ma. This is the Paleocene–Eocene boundary. The swarm represents the only known rocks of that age within several hundred kilometres and may be related to changes in the stress regime during reorganisation of plate movements at 55 Ma when break-up between Greenland and Europe took place.

scholarly journals Middle Holocene Coastal Environmental and Climate Change on the Southern Coast of Korea

2020 ◽  
Vol 11 (1) ◽  
pp. 230
Author(s):  
Hoil Lee ◽  
Jin-Young Lee ◽  
Seungwon Shin
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Stable Carbon Isotopes ◽  
Asian Summer Monsoon ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Freshwater Input ◽  
Reclaimed Land ◽  
Middle Holocene ◽  
Southwest Coast

We obtained a 15 m drill core from Deukryang Bay on the southwest coast of Korea, which is now an area of reclaimed land used for agriculture. We investigated changes in the depositional environment and hydrological climate responses to sea level changes using sedimentary facies, radiocarbon ages, grain-size analysis, total organic carbon (TOC), total sulfur (TS), and stable carbon isotopes (δ13C). Sediment deposition began at 12,000 cal yr BP and was divided into four stages based on changes from fluvial to intertidal environments related to Holocene marine transgression events. Stage 1 (>10,000 cal yr BP) is represented by fluvial sediments; Stage 2 (10,000–7080 cal yr BP) is represented by the deposition of mud facies in an intertidal zone in response to sea level rise; Stage 3 (7080–3300 cal yr BP) was a period of gradually descending sea level following the Holocene maximum sea level and is characterized by gradual changes in TOC, TS, and C/S ratios compared with the mud facies of Stage 2. Stage 4 (3300 to present) was deposited in a supratidal zone and contains low TS and an abundance of TOC. Based on our TS and C/S ratio results, the south coast of Korea was mainly affected by sea level rise between 7000 and 3000 cal yr BP, during the middle Holocene. At 3000 cal yr BP, sea level began to stabilize or gradually decrease. In addition, changes in δ13C values are clearly observed since ca. 5000 cal yr BP, in particular, large hydrological changes via freshwater input are confirmed in 4000–3000 cal yr BP. We consider these shifts in freshwater input indicators of an increased influence of El Niño and La Niña conditions, related to the weakening of the East Asian Summer Monsoon (EASM) and changes in sea surface temperature (SST) of the Western Pacific Ocean during the middle Holocene climatic optimum (between 7800 and 5000 cal yr BP). The cooling periods of SST in East Asia between 8400 and 6600 cal yr BP reported from the west coast of Korea are related closely to changes in vegetation (as evidenced by δ13C) from 7700 cal yrs BP to the present in the southwest coast of Korea. We interpret the freshwater input events at 4000–3000 cal yr BP to be related to changes in SST in response to the weakening of the EASM on the southwest coast of Korea. However, additional research is needed to study the southward migration effect of the westerly jet related to SST and atmospheric circulation controlling terrestrial climate in the middle Holocene.

Characterization and distribution of microplastics in estuarine surface sediments, Kayamkulam estuary, southwest coast of India

2021 ◽  
Vol 168 ◽  
pp. 112389
Author(s):  
K. Radhakrishnan ◽  
V. Sivapriya ◽  
A. Rajkumar ◽  
N. Akramkhan ◽  
P. Prakasheswar ◽  
...  
Keyword(s):  
Surface Sediments ◽  
Southwest Coast Of India ◽  
Southwest Coast

scholarly journals Implications of an extensive salt water barrage on the distribution of black clam in a tropical estuarine system, Southwest coast of India

Oceanologia ◽  
2021 ◽  
Author(s):  
Arunpandi Nagarathinam ◽  
Jyothibabu Retnamma ◽  
Jagadeesan Loganathan ◽  
Parthasarathi Singaram ◽  
Savitha Mohanan ◽  
...  
Keyword(s):  
Salt Water ◽  
Estuarine System ◽  
Southwest Coast Of India ◽  
Southwest Coast ◽  
Tropical Estuarine

An Adaptation Due to Climate Change in Southwest Coast of Taiwan

2013 ◽  
Vol 41 (2) ◽  
pp. 172-189 ◽  
Author(s):  
Yuan-Jyh Lan ◽  
Tai-Wen Hsu ◽  
Yue-Chen Lin ◽  
Ching-Jer Huang
Keyword(s):  
Climate Change ◽  
Southwest Coast
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