Tons of useful info on Ferfal’s blog on the Argentine collapse. Here are some articles I thought would be particularly applicable to your book:
As far as your question about how the cascade effect would occur, it really depends on the catalyst. Did the BRAC dump all their US securities? Did the stock market bubble burst? Drought cause commodities to tank? Did the Fed raise rates too suddenly, or too slowly? As you can see, there are a lot of factors that would dictate the after effects. My suggestion is to not get too caught up in the weeds. Let the ultimate cause of the collapse remain a mystery and stick to the things affecting the main protaganist (bank closures, debit/credit freezes, empty shelves, etc). If you try to get too technical, people will pick your plotline apart and take it too technically. The Road is a good example; we have no clue what the disaster actually was, just that the world became hell on earth afterwards, and what the father had to go through to protect his son. The intrigue adds to the story, in my opinion.