Gulf of Maine currents and their connectivity. A summary.

A step by step  systematic analysis of  Gulf of Maine currents and their interconnections, including potential wind farm impacts. 

I. THE MAINE COASTAL CURRENT SYSTEM:

1. Eastern Maine Coastal Current (EMCC)
Strong, cold current flowing southwestward from Bay of Fundy
Speed: typically 15-30 cm/s
Highly turbulent, well-mixed
Critical for nutrient transport

Potential wind farm impacts:
Reduced current velocity from wind energy extraction
Altered mixing patterns affecting nutrient distribution
Changes in larval transport

2. Western Maine Coastal Current (WMCC)
Weaker continuation of EMCC
More stratified than EMCC
Speed: typically 5-15 cm/s
Significant seasonal variation
Potential wind farm impacts:
Increased mixing could disrupt natural stratification
Wake effects could alter plankton distribution
Changes in temperature structure


II DEEP BASIN GYRES:

1. Jordan Basin Gyre
Cyclonic (counterclockwise) circulation
Important for deep water renewal
Influenced by slope water intrusion
New research shows unique seasonal temperature patterns
Potential wind farm impacts:
Altered vertical mixing affecting deep water properties
Changed nutrient cycling
Modified stratification patterns

2.Wilkinson Basin Gyre
Similar to Jordan Basin but with distinct characteristics
Important for water mass exchange
Strong seasonal variation
Potential wind farm impacts:
Changed circulation patterns
Altered deep water properties
Modified stratification

3. Franklin Basin Gyre
Smaller than Jordan and Wilkinson
Important for local mixing
Connects to other basin systems
Potential wind farm impacts:
Local circulation changes
Modified mixing patterns

III. BOUNDARY CURRENTS:

6. Nova Scotian Coastal Current
Brings fresh water from Scotia Shelf
Critical for stratification
Strong seasonal signal
Potential wind farm impacts:
Altered freshwater transport
Changed stratification patterns
Modified nutrient distribution

7. Slope Water
Warm, saline water entering via Northeast Channel
Critical for nutrient input
Three-month transit time to Jordan Basin

Potential wind farm impacts:

Changed mixing with shelf water
Altered nutrient transport
Modified temperature patterns

IV. REGIONAL FEATURES:

Georges Bank Circulation
Strong tidal mixing
Important for fisheries
Complex frontal systems

Potential wind farm impacts:
Changed mixing patterns
Altered frontal dynamics
Modified nutrient distribution

Bay of Fundy Gyre
World's highest tides
Critical for mixing
Important whale habitat
Potential wind farm impacts:
Modified tidal mixing
Changed upwelling patterns
Altered whale feeding grounds

V. FRONTAL SYSTEMS:

Shelfbreak Front
Separates shelf and slope waters
Important for productivity
Strong seasonal variation
Potential wind farm impacts:
Changed front position
Modified mixing patterns
Altered nutrient exchange

Tidal Mixing Fronts
Important for productivity
Strong seasonal signal
Critical fish habitat
Potential wind farm impacts:
Changed front locations
Modified mixing intensity
Altered habitat characteristics

VI. CUMULATIVE CONSIDERATIONS:

1. Climate Change Interactions:
Gulf warming faster than 99% of global ocean
Changed stratification patterns
Modified current strengths
Wind farm impacts could either amplify or moderate these changes

2. Anthropogenic Pressures:
Fishing pressure
Pollution inputs
Habitat modification
Wind farms add another layer of complexity


Detailing potential wind farm impacts to GOM currents.

SURFACE-LEVEL IMPACTS:

1. Wind Energy Extraction Effects
Reduced wind speeds extending 35-70km downstream
Weakened surface current velocities
Changed upwelling/downwelling patterns
Modified surface mixing intensity

2. Wake Effects
Creation of turbulent zones
Formation of circulation dipoles
Altered plankton distribution patterns
Modified surface temperature patterns

MID-WATER IMPACTS:
1. Stratification Changes
Disrupted temperature layering
Modified density boundaries
Altered seasonal mixing patterns
Changed nutrient distribution

2. Mixing Zone Effects
Enhanced vertical mixing at turbine sites
Modified thermocline depth and strength
Changed internal wave patterns
Altered frontal boundary positions

DEEP WATER IMPACTS:

1. Basin Circulation Changes
Modified gyre strengths and patterns
Altered deep water renewal
Changed bottom water properties
Shifted nutrient cycling patterns

SYSTEM-WIDE EFFECTS

1. Current Interactions
Modified current strengths and paths
Changed intersection points of currents
Altered exchange between current systems
Modified tidal mixing patterns

2. Biological Responses
Changed larval transport patterns
Shifted feeding ground locations
Modified migration pathways
Altered habitat characteristics

================================

END

Penobscot Bay's Tectonic History, September 1995.

FROM: Silurian tectonic history of Penobscot Bay Region, Maine

A look at the geologic history of Penobscot Bay.  September 18, 1995
By:David B. Stewart  John D. Ungerl, & Deborah R. Hutchinson USGS , Reston, Wrginia 22092, U.S.A. and U.S. Geological Survey, Woods Hole, Massachusetts 02543, U.S.A.

Summary  Early Paleozoic amalgamation of composite terranes was contemporaneous at widely separated regions that were later accreted to either ancestral North America or to Gondwana as those two continents approached each other. 

Terranes closer to Laurentia amalgamated in the Late Cambrian to Middle Ordovician Penobscottian orogeny and were accreted to ancestral North America in the Middle and to Late Orodovician Taconic orogeny. 

Peri Gondwanan terranes formed from Late Cambrian and Early Ordovician rocks were amalgamated in the Late Ordovician and Early Silurian to form the Salinic orogenic belt, now exposed from western Europe to southem New England. 

Salinic orogenic activity involved extensive thrust faulting and metamorphism, large strike-slip faults, and plutonism, all of which are represented in coastal Maine.

 In the Penobscot Bay region, Maine, the peri-Gondwanan St. Croix terrane was thrust northwest in the Silurian(?) upon middle amphibolite facies Ordovician and Early Silurian rocks of the Fredericton trough. Seismic reflection profiles show that the thrust fault dips  southeasterly at -30° and becomes listric at about 13 1 2 km. 

The thrust sheet was broken initially by the Late Silurian Penobscot Bay-Smith Cove-North Blue Hill dextral strike-slip fault which juxtaposed the peri-Gondwanan Ellsworth terrane, followed by emplacement of the South Penobscot Intrusive Suite and by a sequence of strike-slip fault Zones each with up to 20 km of dextral Silurian and Early Devonian(’I) movement. 

The strike-slip faults are interpreted to either remain steep until they reach the sole of the thrust sheet or to become listric within the thrust sheet. 

In the Devonian Acadian orogeny, more outboard terranea with Gondwanan aflinitics, like the Avalonian terranes in southem New Brunswick and in eastem Massachusetts, were amalgamated with the Silurian orogenic belt, and the resulting composite terrane was accreted to ancestral North America. Acadian deformation, metamorphism, and plutonism are superimposed on the Silurian orogen, blurring or obliterating the evidence of Silurian orogeny.

End abstract

Sears Island Geologic Fault Investigation Results 1976

SEARS ISLAND FAULT INVESTIGATION
SEARS ISLAND, SEARSPORT, MAINE
March 19, 1976  (263 page pdf; Maps start pg 41

by John R. Rand, Consulting Geologist

Robert G. Gerber, Geologist, Central Maine Power Company for Maine Nuclear Power Station Central Maine Power Company

Augusta, Maine  19 March 1976

Executive Summary

During the course of geologic studies for Central Maine Power Company’s proposed nuclear
power plant on Sears Island in Searsport, Maine, a northeasterly trending, highly weathered rock
zone was inferred about 1,000 feet (300 m.) from the reactor site. 

From April through November 1975, an investigation was conducted centering around two large trenches across the trend of the weathered zone. This report is a summary of the results and interpretations of the investigations performed.

The trenches exposed an ancient fault zone containing highly weathered phyllitic rock. In the

more westerly of the two large trenches, this weathered rock material had locally intruded and
caused minor deformation of Laurentide lodgment till. 

In the more easterly trench, a small bedrock reverse offset was found on the east wall with associated disturbance of overlying glacial till. On the west wall of the easterly trench, a small monoclinal flexure was found at the  till/bedrock interface. 

The investigators conclude that the bedrock fault zone experienced its last tectonic movement in Pre-Cenozoic time. 

The deformation of the tills over the fault zone is interpreted to have occurred approximately 13,500 to 12,800 years ago as a result of the weaker,  weathered rock having been squeezed between the adjacent harder bedrock masses. 

This squeezing produced either a forceful intrusion of highly weathered material into the till or an
arching of somewhat more competent but still relatively weaker rock in the fault zone. 

The squeezing and arching was a result of 1) lateral stress relief of the harder bedrock into the softer
fault zone materials during glacial unloading and/or

 2) a horizontal stress against the weaker fault zone rock through southeasterly directed base shear and stress distribution from the weight of a glacial lobe advance during the final overall glacial recession.

There is no evidence to indicate a tectonic origin of the till deformation.

END

John R. Rand, consulting geologist and Maine Certified Geologist #2, directed the investigation
and mapping of the bedrock geology and is a co-author of this report. Robert G. Gerber,
geologist for Central Maine Power Company and Maine Certified Geologist #110, directed the
investigation and mapping of the surficial geology and is a co-author of this report.

wrfr 12/14/24

 

Mapping the Patriarchy in Conservation

Leonie Bossert, Tom Crompton, Anwesha Dutta, Joni Seager
Biodiversity, Volume 3, Article 38, 12 December 2024

https://www.nature.com/articles/s44185-024-00072-4Abstract

https://penbay.org/wrfr/2024/mepub_oped_draft_121424.txt

Iyt can't happen here sinclair lewis

https://penbay.org/wrfr/2024/it_cant_happen_here/

Gulf of Maine stratification and windturbines

• Offshore wind farms can impact hydrodynamics
in the surrounding ocean in two principal ways:

 1) through an atmospheric wake effect that reduces
wind speeds behind wid turbines that can
reach the ocean surface, reducing surface wind
stress and wind-induced currents, and

 2) through subsurface mixing induced by the presence 

of the turbine substructure within the water column.

• Hydrodynamics and wind wake effects around
offshore wind turbines are driven by physical
ocean processes including tides, stratification,
water depth, and wind-driven currents; and atmospheric
processes such as turbulence and stability,
all of which have significant natural variation.

• Changes in surface currents and sea surface
temperatures caused by turbines in European
windfarms (e.g., North Sea) are small enough that
they can be difficult to isolate from other sources
of natural variability.

• Although studies from the North Sea suggest that
wind turbines could cause mixing and disrupt
the tratification of ocean waters, wind turbines
in the Mid-Atlantic Bight are unlikely to have
much influence on summer stratification, which
is significantly stronger than the weakly stratified
waters of the North Sea.

• Due to the distinct oceanographic differences
between the North Sea and the Western North
Atlantic Ocean (and among regions therein),
impacts of wind turbines in one region are not
necessarily directly transferrable to other regions.

• Increased turbulent mixing caused by wind
turbines may enhance nutrient mixing and
stimulate primary production, in turn enhancing
zooplankton abundance, including copepods.

However, if turbulence levels are significant and
cause sediment resuspension, primary production
may decrease due to reduced light penetration.

• Hydrodynamic impacts are highly dependent on
wind farm layout and wind turbine parameters,
including turbine size (hub height and power
capacity), type of foundation, turbine spacing
within the wind farm, and the spacing between
adjacent wind farms.

• Extensive build-out of offshore wind farms is likely
necessary for these structures to have a significant
hydrodynamic impact.

• Larger, more widely spaced turbines, such as
those being planned for U.S. windfarms, are likely
to have less hydrodynamic influence than the
smaller, more closely spaced turbines currently in
operation in Europe and other parts of the world.

Oceanographic Effects