Pb-Pb dating of individual chondrules from the CB_a chondrite Gujba: assessment of the impact plume formation model

TY - JOUR

T1 - Pb-Pb dating of individual chondrules from the CBa chondrite Gujba

T2 - assessment of the impact plume formation model

AU - Bollard, Jean Francois André

AU - Connelly, James

AU - Bizzarro, Martin

PY - 2015

Y1 - 2015

N2 - The CB chondrites are metal-rich meteorites with characteristics that sharply distinguish them from other chondrite groups. Their unusual chemical and petrologic features and a young formation age of bulk chondrules dated from the CBa chondrite Gujba are interpreted to reflect a single-stage impact origin. Here, we report high-precision internal isochrons for four individual chondrules of the Gujba chondrite to probe the formation history of CB chondrites and evaluate the concordancy of relevant short-lived radionuclide chronometers. All four chondrules define a brief formation interval with a weighted mean age of 4562.49±0.21Myr, consistent with its origin from the vapor-melt impact plume generated by colliding planetesimals. Formation in a debris disk mostly devoid of nebular gas and dust sets an upper limit for the solar protoplanetary disk lifetime at 4.8±0.3Myr. Finally, given the well-behaved Pb-Pb systematics of all four chondrules, a precise formation age and the concordancy of the Mn-Cr, Hf-W, and I-Xe short-lived radionuclide relative chronometers, we propose that Gujba may serve as a suitable time anchor for these systems.

AB - The CB chondrites are metal-rich meteorites with characteristics that sharply distinguish them from other chondrite groups. Their unusual chemical and petrologic features and a young formation age of bulk chondrules dated from the CBa chondrite Gujba are interpreted to reflect a single-stage impact origin. Here, we report high-precision internal isochrons for four individual chondrules of the Gujba chondrite to probe the formation history of CB chondrites and evaluate the concordancy of relevant short-lived radionuclide chronometers. All four chondrules define a brief formation interval with a weighted mean age of 4562.49±0.21Myr, consistent with its origin from the vapor-melt impact plume generated by colliding planetesimals. Formation in a debris disk mostly devoid of nebular gas and dust sets an upper limit for the solar protoplanetary disk lifetime at 4.8±0.3Myr. Finally, given the well-behaved Pb-Pb systematics of all four chondrules, a precise formation age and the concordancy of the Mn-Cr, Hf-W, and I-Xe short-lived radionuclide relative chronometers, we propose that Gujba may serve as a suitable time anchor for these systems.

U2 - 10.1111/maps.12461

DO - 10.1111/maps.12461

M3 - Journal article

C2 - 27429545

AN - SCOPUS:84937073939

SN - 1086-9379

VL - 50

SP - 1197

EP - 1216

JO - Meteoritics and Planetary Science

JF - Meteoritics and Planetary Science

IS - 7

ER -