Abstract: Qinling Orogenic Belt represents the composite convergence gone with two sutures between the North China and Yangtze blocks (NCB and YB). The northern Neoproterozoic to Early Paleozoic Shang-Dan megasuture, in which were tectonically emplaced ophiolite fragments including the well known Songshugou ophiolite(1000 Ma±), is the boundary between North Qinling (NQ)and South Qinling(SQ). The southern Late Paleozoic Mian-Lue suture with ophiolite fragments is situated between SQ and the northern margin of Yangtze block (NYB), and thereby is considered to represent an ocean basin opened and closed within the Yangtze plate. The regional continental growth has been studied based oil Nd model ages and the chemieal characteristics, depletion degree and evolution tendency of the regional upper mantle have been revealed by trace element and isotopic tracers. The results indicate that NQ is basically similar to SQ and NYB in the continental growth mainly during the Paleo-and Meso-Proterozoic, the higher depletion degree (εNd(t) up to +7.5)of the Proterozoic upper mantle, and the Proterzoic mantle chemical features of relative enrichment in Nb, Ta and Cu, and higher Rb/Sr, Ba/Sr, Ba/La, Th/La and Nb/Ta ratios. In contrast, the continental crust of NCB and its southern margin (SNCB) grew mainly during the Archean and Paleoproterozic, their upper mantle was almost steady in its εNd(t) values of about +3 during the same time interval, and the mantle source of the Paleoproterzoic basalts of SNCB was characterized by relative enrichment in Fe and Mo and higher Zr/Hf ratio. The Pb isotopic thee dimensional topological plot and the 206Pb/204Pb-εNd(t) plot for the basement basic rocks from the region consistently show an outstanding geochemical boundary in coincidences with the geological boundary between NQ and NCB, and a subordinate geochemical boundary at the Shang-Dan megasuture. In the Songshugou ophiolite fragment, the discovery of metatholeiites, exhibiting the chemical features peculiar to both N-MORB and E-MORB implies that coexisted the depleted mantle source and mantle plume source beneath the Shang-Dan ocean basin represented by the ophiolite. The N-MORB-type metatholeiite of Songshugou ophiolite is comaparable to the N-MORB-type metatholeiite of Mian-Lue ophiolite in Ba/La, Nb/Ta, Yb/Hf, Y/Tb, Ti/Zr and Ti/V ratios, and Nd and Pb isotopic composition. This infers that the Shang-Dan oceanic crust, like the Mian -Lue oceanic crust, was formed within the Yangtze plate via the lithospheric break-up. In addition, the Qinling region was dominated by the rifting series during the Paleo-and Meso-Proterozoic and no sutured boundary of that time has be en discovered. Therefore, NQ should be a part of the Yangtze plate before the Neoproterozoic. The metatholeiites of Qinling Group(2000 Ma±)and Kuanping Group(1 142 Ma±)are similar to the Songshugou metatholeiites of both the E-MORB and N-MORB types in higher Nb/Ta, Ba/La, Nb/La, Th/La, Sc/Th and Yb/Hf ratios, and are comparable to the E-MORB-type metatholeiite in higher Nb, Ta, U and Th contents. This result not only may be in support of the supposition that NQ was originally a microcontinent formed on an ocean is1and base, but also can give a reasonable interpretation for that the crust and mantle of NQ are characterized by the highest Th/La, Sc/Th and Yb/Hf ratios, the highest Nb,Ta, U and Th contents and the highest Pb isotopic ratios in the region. Finally, the implications of this study for the developing dynamics of Qinling Orogen are also discussed.