СТРУКТУРНАЯ ЭВОЛЮЦИЯ ОКЕАНИЧЕСКИХ КОРОВЫХ КОМПЛЕКСОВ: КОНЦЕПЦИЯ, ОСНОВАННАЯ НА АНАЛОГОВОМ МОДЕЛИРОВАНИИ

Комплексы океанических ядер представляют собой литологические ассоциации преимущественно перидотитов и серпентинитов, которые располагаются вдоль пересечений медленноспрединговых океанических рифтов и разломных зон, локализованных в основном в базальтовой океанической литосфере; при этом молодые и древние базальты соседствуют по всей разломной зоне. Модели, разработанные на базе экспериментов с использованием центрифуги, показывают, что субдукция начинается на участках, где две литосферные плиты располагаются рядом друг с другом, при условии, что разность плотностей контактирующих литосферных слэбов составляет не менее 200 кг/м3, а трение вдоль плоскости их контакта низкое. Установлено, что в предполагаемой модели более плотная литосфера под давлением может достигать астеносферы, что представляет собой модель тектонической субдукции. Во многих случаях растяжение надвигающейся плиты приводит к развитию сбросов, в которые могут проникать более легкие части опускающейся плиты, вследствие чего возникают вулканы и диапиры. Эксперименты показывают, что, поскольку требуемые условия контрастности плотностей и низкого трения могут быть характерны для участков, где разломные зоны пересекаются с медленноспрединговыми океаническими хребтами, процессы, подобные субдукции могут происходить и на таких участках, а не только вдоль границы океан – континент. Более того, поскольку температурный градиент в зоне пересечения океанического хребта и разломной зоны очень высокий и летучие вещества поднадвигового слэба присутствуют в большом количестве в субдуцируемом слэбе, базальты в поднадвиговом слэбе будут частично подвергнуты серпентинизации, а другая часть – перидотитизации. Также можно предполагать, что легкие серпентиниты будут подниматься по сбросам в надвигающийся слэб и достигнут морского дна в виде диапиров, принося с собой большие объемы перидотитов, что приведет к образованию серпентинит-перидотитовых пород, типичных для комплексов океанических ядер на участках, где разломные зоны пересекаются с медленноспрединговыми океаническими хребтами.

субдукция, обусловленная разной плотностью пород, пересечение хребта и трансформного разлома, комплексы океанических ядер, перидотиты, серпентиниты

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