Is it possible that mount Zion and mount Moriah are not the same?
When Abram rescued Lot, the king of Salem came out to meet him.

Genesis 14:18 And Melchizedek king of Salem brought forth bread and wine: and he was the priest of the most high God.

Salem is Zion:

Psalms 76:2 In Salem also is his tabernacle, and his dwelling place in Zion.

Then when Abraham was called to sacrifice Isaac, it was mount Moriah, not in Salem/Zion.

Genesis 22:2 And he said, Take now thy son, thine only son Isaac, whom thou lovest, and get thee into the land of Moriah; and offer him there for a burnt offering upon one of the mountains which I will tell thee of.

As soon as David was anointed king over all Israel, the first thing he did was to take Zion:

II Samuel 5:7 Nevertheless David took the strong hold of Zion: the same is the city of David.

Then David the ark brought into the city of David, the stronghold of Zion.
David a pitched a tent/tabernacle in Zion for the ark:

I Chronicles 15:1 And David made him houses in the city of David, and prepared a place for the ark of God, and pitched for it a tent.
  :3 And David gathered all Israel together to Jerusalem, to bring up the ark of the LORD unto his place, which he had prepared for it.
  28 Thus all Israel brought up the ark of the covenant of the LORD with shouting, and with sound of the cornet, and with trumpets, and with cymbals, making a noise with psalteries and harps.
  29 And it came to pass, as the ark of the covenant of the LORD came to the city of David, that Michal the daughter of Saul looking out at a window saw king David dancing and playing: and she despised him in her heart.

I Chronicles 16:1 So they brought the ark of God, and set it in the midst of the tent that David had pitched for it: and they offered burnt sacrifices and peace offerings before God.

II Samuel 6:17 And they brought in the ark of the LORD, and set it in his place, in the midst of the tabernacle that David had pitched for it: and David offered burnt offerings and peace offerings before the LORD.

The LORD between the cherubims, upon the ark, in Zion:

Psalms 9:11 Sing praises to the LORD, which dwelleth in Zion: declare among the people his doings.

I Chronicles 17:5 For I have not dwelt in an house since the day that I brought up Israel unto this day; but have gone from tent to tent, and from one tabernacle to another.

Apparently David built out from there, to include the greater Jerusalem area.
Then, when David numbered Israel, the angel of the LORD, was killing people in Jerusalem.
The LORD stopped the killing when the angel was at the threshing floor of Ornan the Jebusite:

I Chronicles 21:15 And God sent an angel unto Jerusalem to destroy it: and as he was destroying, the LORD beheld, and he repented him of the evil, and said to the angel that destroyed, It is enough, stay now thine hand. And the angel of the LORD stood by the threshingfloor of Ornan the Jebusite.
  16 And David lifted up his eyes, and saw the angel of the LORD stand between the earth and the heaven, having a drawn sword in his hand stretched out over Jerusalem. Then David and the elders of Israel, who were clothed in sackcloth, fell upon their faces.

Later, Solomon built the temple on the threshing floor of Ornan, called mount Moriah:

II Chronicles 3:1 Then Solomon began to build the house of the LORD at Jerusalem in mount Moriah, where the LORD appeared unto David his father, in the place that David had prepared in the threshingfloor of Ornan the Jebusite.

Mount Moriah was outside of Zion, the city of David, where the ark still was:

I Kings 8:1 Then Solomon assembled the elders of Israel, and all the heads of the tribes, the chief of the fathers of the children of Israel, unto king Solomon in Jerusalem, that they might bring up the ark of the covenant of the LORD out of the city of David, which is Zion.

So, later, when Jesus will reign upon the earth, will it be from mount Moriah, or mount Zion?

Psalms 2:6 Yet have I set my king upon my holy hill of Zion.

Micah 4:7 And I will make her that halted a remnant, and her that was cast far off a strong nation: and the LORD shall reign over them in mount Zion from henceforth, even for ever.

At that time, will the tabernacle of David, which was in Zion, be raised back up?

Isaiah 16:5 And in mercy shall the throne be established: and he shall sit upon it in truth in the tabernacle of David, judging, and seeking judgment, and hasting righteousness.

Amos 9:11 In that day will I raise up the tabernacle of David that is fallen, and close up the breaches thereof; and I will raise up his ruins, and I will build it as in the days of old:

Acts 15:16 After this I will return, and will build again the tabernacle of David, which is fallen down; and I will build again the ruins thereof, and I will set it up:

So, is it possible that mount Zion and mount Moriah are not the same?