«Severalmaz» Company, Arkhangelsk, Russia:

Fomin A. A., Chief Geologist of Lomonosov Ore Mining and Processing Enterprise, e-mail: AFomin@severalmaz.ru

Arkhangelskaya pipe occupies an extreme position on South flange of Lomonosov diamond deposit. This pipe is related to weekly eroded large ore deposits.
Arkhangelskaya pipe has a pear-shaped form in plan under the block deposits. Due to the dyke-form ledge on South-Eastern flange, a correct oval look of this form is complicated.
General spread of a cymberlite body is 25°. Pipe sizes on a long and short axes are 550×490 meters. Area is 149 930 square meters.
In vertical incision, ore deposit has a funnel-shaped form, which is typical for kymberlite pipes. This form is complicated by a funnelshaped opening in a top part. Internal structure of Arkhangelskaya pipe is complex. Both in plan and in vertical incision, the heterogeneous character of a pipe diamond content is directly related to its attitude position, as well as to the peculiarities of it`s internal structure : lithologic composition and diamond content of kymberlite formations.
Diathermic part of Arkhangelskaya pipe is formed by one variety of kimberlites – autolith breccias of vent fraction, which form a shoot within its limits. This shoot is steep-grade on the North-East at angle of 85°. Sizes of the shoot are 405×395 meters at the top level (on the depth 159,5 meters from day surphase), area is 97 297 square meters. According to the information of a coring acquisition, an average contain of diamonds in the shoot doubles a diamond content in А-2а-В block, which is been currently processing.

1. Pylaev N. F. Materialy po operativnomu izmeneniyu zapasov po bloku A-2a-B trubki “Arkhangelskaya” mestorozhdeniya imeni M. V. Lomonosova po rezultatam provedeniya geologorazvedochnykh rabot za period 2004–2010 i pereotsenki zapasov po sostoyaniyu na 01.01.2011 (Materials on the rapid changes in reserves on A-2a-B block of Arkhangelskaya pipe on Lomonosov deposit as a result of exploration works for the period from 2004 till 2010 and revaluation of reserves as of 01.01.2011). Fondy OAO “Severalmaz” (Foundations of “Severalmaz” JSC). 2011.

2. Medvedev V. A., Pylaev N. F., Veselov V. I. Otchet o rezultatakh dorazvedki trubki “Arkhangelskaya” i predvaritelnoy razvedki trubki “Snegurochka” mestorozhdeniya imeni M. V. Lomonosova v 1987–1991 s podschetom zapasov almazov po sostoyaniyu na 01.03.1991 (A report on the results of additional exploration of Arkhangelskaya pipe and preliminary exploration of Snegurochka pipe on Lomonosov deposit from 1987 till 1991 with the calculation of diamond reserves as of 01.03.1991). Fondy OAO “Severalmaz” (Foundations of “Severalmaz” JSC). 2011.