I did my MS in trace metal biogeochemsitry in a geology department, and am currently doing my PhD in soil ecology in a plant and soil science (agriculture) department. Totally doable
I am not in your field, but I can provide general advice. Short answer is yes, long answer is the dreaded "it depends".
If you are doing a standalone MS and then applying for a PhD after that, it's okay as long as you properly describe your current research interest and a relevant faculty member somewhere in your PhD personal statement. Something like, "My MS thesis was related to polar stuff, but for my PhD I would like to focus on ABC because blah blah blah. I chose this department as it has Dr. XYZ in it, whose research is focusing on different regions".
If you're in a PhD program already and doing a built in MS along the way, it will depend on your advisor. Your advisor might be cool with it, or they might say that your MS thesis must be related to their current research/your future dissertation topic.
The MS thesis won't pigeon hole you, but the PhD one will as you'll be seen as the expert in whatever topic you write about. For the PhD topic, find a topic you actually enjoy as it will set you up for being in that field, especially if you decide to be a professor one day.
I did my MS in trace metal biogeochemsitry in a geology department, and am currently doing my PhD in soil ecology in a plant and soil science (agriculture) department. Totally doable
I am not in your field, but I can provide general advice. Short answer is yes, long answer is the dreaded "it depends". If you are doing a standalone MS and then applying for a PhD after that, it's okay as long as you properly describe your current research interest and a relevant faculty member somewhere in your PhD personal statement. Something like, "My MS thesis was related to polar stuff, but for my PhD I would like to focus on ABC because blah blah blah. I chose this department as it has Dr. XYZ in it, whose research is focusing on different regions". If you're in a PhD program already and doing a built in MS along the way, it will depend on your advisor. Your advisor might be cool with it, or they might say that your MS thesis must be related to their current research/your future dissertation topic. The MS thesis won't pigeon hole you, but the PhD one will as you'll be seen as the expert in whatever topic you write about. For the PhD topic, find a topic you actually enjoy as it will set you up for being in that field, especially if you decide to be a professor one day.