Thick (∼800 m) basaltic successions from the eastern Antarctic Peninsula have been dated in the interval 180 – 177 Ma and preserve a transition from a continental margin arc to a back-arc extensional setting. Amygdaloidal basalts from the Black Coast region of the eastern margin of the Antarctic Peninsula represent a rare onshore example of magmatism associated with back-arc extension that defines the early phase of Weddell Sea rifting and magmatism, and Gondwana breakup. The early phase of extension in the Weddell Sea rift system has previously been interpreted to be related to back-arc basin development with associated magnetic anomalies attributed to mafic-intermediate magmatism, but with no clearly defined evidence of back-arc magmatism. The analysis provided here identifies the first geochemical evidence of a transition from arc-like basalts to the development of depleted back-arc basin basalts in the interval 180 – 177 Ma. The exposed Black Coast basaltic successions are interpreted to form a minor component of magmatism that is also defined by onshore sub-ice magnetic anomalies, as well as the extensive magnetic anomalies of the southern Weddell Sea. Back-arc magmatism is also preserved on the Falkland Plateau where intrusions postdating 180 Ma are associated with early phase rifting in the Weddell Sea rift system. Back-arc extension was probably short-lived and had ceased by the time the northern Weddell Sea magmatism was emplaced (<175 Ma) and certainly by 171 Ma, when an episode of silicic magmatism was widespread along the eastern Antarctic Peninsula. Previous attempts to correlate mafic magmatism from the eastern Antarctic Peninsula to the Ferrar large igneous province, or, as part of a bimodal association with the Chon Aike silicic province are both dismissed based on age and geochemical criteria.
The Cape Shore Chorus, a local chapter of Sweet Adelines International, will be performing at the Ocean City Music Pier on Sunday, Oct. 20. The performance of “Rock Around the Clock” will feature music selections that will demonstrate the best of women’s four-part a cappella singing and include songs that will take the audience through a history of rock and roll music. Featured guests include Just 4 Kicks, a 2018 Sweet Adelines Regional Champion Quartet from Waldwick, N.J., and the Stockton University a cappella singers – Stockapella and The Stocktones.The performance starts at 3 p.m. Tickets are $15 and can be purchased at the door on the day of the event. Cape Shore Chorus is a non-profit organization and funding for the event comes in part from a Cape May County Arts Re-Grant. Ticket proceeds support the annual scholarship fund that is awarded to a graduating female who has been active in performing arts during high school. Although it is a competitive scholarship for area high schools, the 2018 and 2019 scholarship has been awarded to a graduate of Ocean City High School.Cape Shore Chorus is also inviting women of all ages to join chorus rehearsals for the next month, learn some classic holiday music in the barbershop style, and sing with the chorus during its December concerts.No experience or special training is necessary. The first rehearsal will be on Thursday, Oct. 24, at the Upper Township Community Center, 1709 Route 50 in Tuckahoe, beginning at 7:45 p.m. Call Betsy for more information at 609-425-4648.