Database
[{"observation":{"temporalExtent":[{"dateBeg":ISODate("2002-07-28T20:47:00.000+02:00"),"dateEnd":ISODate("2003-09-13T16:17:00.000+02:00")}]}}]
Query
db.collection.aggregate({"$match":{"observation.temporalExtent":{"$elemMatch":{"dateBeg":{"$gte":{"$dateFromString":{"dateString":"1892-01-05T23:50:39.000Z"}}}}}}})