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Post-early Cretaceous Mississippi Valley-type Zn-Pb mineralization in the Bongara area, northern Peru: Fluid evolution and paleo flow from fluid inclusion evidence
Basuki N.I.a,b, Spooner E.T.C.a
a F. Gordon Smith Fluid Inclusion Lab., Department of Geology, University of Toronto, Canada
b Department of Geology, Institut Teknologi Bandung (ITB), Indonesia
[vc_row][vc_column][vc_row_inner][vc_column_inner][vc_separator css=”.vc_custom_1624529070653{padding-top: 30px !important;padding-bottom: 30px !important;}”][/vc_column_inner][/vc_row_inner][vc_row_inner layout=”boxed”][vc_column_inner width=”3/4″ css=”.vc_custom_1624695412187{border-right-width: 1px !important;border-right-color: #dddddd !important;border-right-style: solid !important;border-radius: 1px !important;}”][vc_empty_space][megatron_heading title=”Abstract” size=”size-sm” text_align=”text-left”][vc_column_text]The Bongara area, northern Peru, contains Zn-Pb mineralization with characteristics typical of Mississippi Valley-type (MVT) systems. The northwest-southeast-trending late Triassic-Jurassic carbonate host rocks of the Pucará Group were locally replaced by early (D1) and late (D2) dolomite. Fluid inclusion microthermometric data from dolomite and sphalerite are typical of MVT ore fluids (78° to 187°C; ∼ 15-23 wt.% CaCl2 equivalent), and do not show apparent covariation between temperature and salinity. Homogenization temperature data from D1 and D2 dolomite show a decrease from northern (mean Th = 138°C) to central (mean Th = 126°C) to southern areas (mean Th = 102°C), suggesting fluid flow from north to south. Assuming a geothermal gradient of ∼30°C/km and an average surface temperature of ∼20°C, the lower temperature limits might approximate the ambient host-rock temperatures, whereas the upper temperature limits may represent minimum temperatures of a deeper aquifer, probably at a maximum depth of ∼6000 m. The lower temperature limits are also similar to the estimated temperatures if dolomitization and mineralization took place in the Late Cretaceous at ∼2000-3000 m depth, probably during the formation of the Peruvian fold and thrust belt near the present day Peru-Ecuador border. Fluid inclusion data show that the fluids in each studied location had relatively uniform temperatures and salinities during dolomitization and mineralization. A significant salinity drop and a slight temperature decrease are observed during late calcite precipitation, suggesting mixing of brines with dilute, cooler fluids. © 2009 Canadian Institute of Mining, Metallurgy and Petroleum. All rights reserved.[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Author keywords” size=”size-sm” text_align=”text-left”][vc_column_text]Calcite precipitation,Fluid inclusion,Fold-and-thrust belts,Homogenization temperatures,Lower temperature limits,Northern Peru,Orogenic events,Pucara group[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Indexed keywords” size=”size-sm” text_align=”text-left”][vc_column_text]Fluid inclusions,MVT,Northern Peru,Peruvian orogenic event,Pucara group[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Funding details” size=”size-sm” text_align=”text-left”][vc_column_text][/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”DOI” size=”size-sm” text_align=”text-left”][vc_column_text]https://doi.org/10.2113/gsemg.18.1-4f.25-a[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/4″][vc_column_text]Widget Plumx[/vc_column_text][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][/vc_column][/vc_row]