Academic literature on the topic 'Casco Bay Group'

Ordovician metamorphic rocks of the Casco Bay Group are exposed in an approximately 170 km long NE-trending belt (Liberty-Orrington belt) in southern and south-central Maine. Geochemical analysis of rocks within the Spring Point Formation (469±3 Ma) of the Casco Bay Group indicate that it is an assemblage of metamorphosed bimodal volcanic rocks. The mafic rocks (originally basalts) have trace element and Nd isotopic characteristics consistent with derivation from a mantle source enriched by a crustal and/or subduction component. The felsic rocks (originally rhyolites and dacites) were likely generated through partial melting of continental crust in response to intrusion of the mafic magma. Relatively low initial εNd values for both the mafic (−1.3 to +0.6) and felsic (−4.1 to −3.8) rocks suggest interactions with Gander zone continental crust and support a correlation between the Casco Bay Group and the Bathurst Supergroup in the Miramichi belt of New Brunswick. This correlation suggests that elements of the Early to Middle Ordovician Tetagouche-Exploits back-arc basin can be traced well into southern Maine. A possible tectonic model for the evolution of the Casco Bay Group involves the initiation of arc volcanism in Early Ordovician time along the Gander continental margin on the eastern side of the Iapetus Ocean basin. Slab rollback and trenchward migration of arc magmatism initiated crustal thinning and rifting of the volcanic arc around 470 Ma and resulted in the eruption of the Spring Point volcanic rocks in a back-arc tectonic setting.

The Casco Bay Group in south-central Maine consists of a sequence of Late Cambrian to Early Ordovician interlayered quartzofeldspathic granofels and pelite (Cape Elizabeth Formation) overlain by Early to Late Ordovician back-arc volcanic (Spring Point Formation) and volcanogenic sedimentary rocks (Diamond Island and Scarboro formations). These rocks were tightly folded and subjected to low-pressure amphibolite-facies metamorphism in the Late Silurian. This phase of deformation and metamorphism was followed by the development of a variety of structures consistent with a period of dextral transpression in Middle Devonian – Early Carboniferous time. Previously dated plutons within the sequence range in age from 422–389 Ma and record a period of prolonged intrusive activity in the region. Similarities in age, volcanic rock geochemistry, and lithologic characteristics argue strongly for a correlation between rocks of the Casco Bay Group and those in the Miramichi belt of eastern Maine and northern New Brunswick. The Cape Elizabeth Formation correlates with Late Cambrian to Early Ordovician sediments of the Miramichi Group (Gander Zone) and the Spring Point through Scarboro formations correlate with Early to Late Ordovician back-arc basin volcanics and volcanogenic sediments of the Bathurst Supergroup. The folding and low-pressure metamorphism of the Casco Bay Group is attributed to Late Silurian to Early Devonian terrane convergence and possible lithospheric delamination that would have resulted in a prolonged period of intrusive activity and elevated temperatures at low pressures. Continued convergence and likely plate reconfigurations in the Middle Devonian to Carboniferous led to widespread dextral transpression in the region.

ABSTRACT In an effort to make a waterfowl population with a limited breeding range—Maine to the Canadian Maritimes—less vulnerable to local catastrophe from petroleum activities, a population of common eiders (Somateria mollissima dressesi) was transplanted from Maine to Massachusetts. The objective of the relocation of the eiders was to see if a population of seabirds could successfully be moved from an area subject to petroleum activities to a new breeding ground. This move involved taking a group of birds from its existing breeding ground to a nonbreeding territory and establishing another breeding population. Such wildlife management techniques could contribute to increasing the reproductive potential of birds lost to oil spills, thus decreasing the need for high-cost oiled bird rehabilitation, which is often ecologically unsound. From 1973 to 1975, adult eiders and eggs were collected from Casco Bay, Maine. Eggs were hatched and hand-reared for several weeks both at the Wildlife Rehabilitation Center and on Penikese Island in Massachusetts. The birds were released on Penikese in Buzzard's Bay, about 240 kilometers (150 miles) south of their known breeding range, but in an area of habitat similar to that of the islands of Casco Bay. An acclimation program included rearing the birds at the release site for one to three weeks and introducing a saltwater environment and natural foods to the birds. The released eiders began breeding in 1976 on Penikese and have since colonized at least three nearby islands. By 1988 the population had increased to an estimated 200 breeding pairs.

e18009 Background: Homeless people encounter many barriers to healthcare and preventative services, while having an increased prevalence of most risk factors for cancer. A group of homeless adults (40) receiving services from Preble Street in Portland Maine were successfully provided access, support and coaching to participate in colon cancer screening using Fecal Immunochemical Test (FIT) over a period of six weeks. Maine Medical Center Cancer Institute (MMCCI) recruited a Physician champion, while Preble Street gathered multiple internal and external community partners and together help plan the project identify resources needed, plan for data collection and address potential barriers for participation. Methods: Community partners (MMCCI, Preble Street, Casco Bay Surgery, NorDx, MaineHealth Care Partners and Homeless Health Partners Case Managers, Me Health LRC, and Maine Medical Center Magnet Council) created a detailed protocol to be used to overcome barriers and facilitate screening. The combination of a simple screening tool and caseworker relationship proved to be an effective strategy. Community Partners were used to identify barriers in the process, monitor all test results and navigate patients testing positive to colonoscopy. Small incentives of $10 food cards were provided for those participating in the screening event. Results: Of the 40 participants who were screened 8 (20%) tested positive and are in colonoscopy follow-up, with ages ranging from 50-74 years. The majority of participants 28 (70%) reported never having a provider conversation about colon cancer screening. Conclusions: Providing cancer prevention education and access to screening can have a positive impact on early detection in the homeless population. Identifying practical barriers and solutions are essential to improving cancer screening participation for homeless people.

The bedrock geology of south-central Maine is characterized by a series of fault-bounded lithotectonic terranes that were accreted onto the Laurentian margin during Silurian-Devonian orogenesis. The multiple phases of deformation and metamorphism associated with this tectonism obscured most primary features in the protolith rocks, leading to uncertainties in their pre-accretionary history. Here we present the results of detrital zircon geochronology from five of these terranes and make interpretations on their depositional ages, sediment provenance, and tectonic setting of deposition.Detrital zircon from Silurian rocks of the Vassalboro Group in the eastern-most portion of the Central Maine basin indicate sediment input in an extensional setting from both Laurentian and Ordovician sources. Results from Ordovician rocks of the Casco Bay Group of the Liberty-Orrington belt support earlier findings that these rocks have strong peri-Gondwanan affinities. Detrital zircon from the Appleton Ridge Formation and Ghent phyllite of the Fredericton trough are consistent with a peri-Gondwanan sediment source with no evidence of Laurentian sediment input. These findings are consistent with that of Dokken et al. (2018) for older Fredericton trough strata (i.e., Digdeguash Formation) east of the Fredericton fault in southern New Brunswick. Two samples from the Jam Brook complex reveal extreme differences in depositional age (Ordovician vs. Mesoproterozoic) and tectonic affinity and support the hypothesis that this narrow belt represents a fault complex containing a wide variety of stratigraphic units. Detrital zircon from Ordovician rocks of the Benner Hill Sequence indicate a peri-Gondwanan sediment source with no Laurentian input.Collectively, the pre-Silurian rocks of the Liberty-Orrington belt, Jam Brook complex, Benner Hill Sequence, and Late Ordovician-Early Silurian strata from the Appleton Ridge and Ghent phyllite in the Fredericton trough show peri-Gondwanan affinities with no evidence of Laurentian sediment input. This suggests a barrier exisited between the Laurentian margin and these peri-Gondwanan terranes prior to about 435 Ma. In contrast, Silurian strata from the eastern portion of the Central Maine basin do show evidence of a Laurentian sediment source, along with deposition in an extensional setting (lacking in all other samples), thus signaling a fundamental change in tectonic regime.